This research was supported by the Case Comprehensive Cancer Center (P30 CA43703).

1. Stereotactic Cyberknife Radiosurgery Consultation
<ol>
	<li>Describe Cyberknife radiosurgery treatment. Cyberknife radiosurgery involves use of a linear accelerator mounted on an industrial robotic arm similar to machines used to make automobiles. The robotic arm moves the linear accelerator in three-dimensional space around a patient as it progresses through multiple treatment 'stops' for beam delivery. Cross-plane x-rays are obtained during treatment to verify the patient is in a correct treatment position. Since treatment beam delivery is not restricted to a two dimensional plane, this system further enhances the ability to deliver concentrated radiation doses to cancer targets while minimizing the radiation dose to critical skin and visceral organ structures.</li>
	<li>Discuss Cyberknife radiosurgery risks. Cyberknife radiosurgery may result in possible tanning and reddening of skin, fatigue, infrequent nausea or diarrhea, rare visceral organ injury, muscle, nerve, and bone injury, and very small risk of second cancer.</li>
</ol>
2. Stereotactic Cyberknife Radiosurgery Fiducial Placement
<ol>
	<li>Describe fiducial placement. Women being treated for persistent or recurrent gynecologic cancers undergo operative or CT-guided placement of at least three single 1.6 x 3 mm gold soft tissue fiducials (about the size of a grain of rice) within or near the cancer target. Surgical clips placed at the time of prior surgery are not of sufficient density to be used as radiosurgical fiducials. Surgical clips do not interfere with radiosurgical targeting because of the density discrepancy.</li>
	<li>Indicate fiducial positioning relative to radiosurgical target. Fiducials are placed at varying tissue depths around the radiosurgical target and must be separated by two centimeters or more. Fiducials are positioned within 4 to 6 centimeters of the target.</li>
</ol>
3. Stereotactic Cyberknife Radiosurgery Treatment Planning
<ol>
	<li>Discuss radiosurgical treatment planning. At least one week after fiducial placement (i.e., so that healing has occurred and fiducial movement is minimized), patients undergo CT-guided SBRT treatment simulation. In our program, two-pin localized evacuated vacuum-bag pelvic immobilization is used.</li>
	<li>Indicate patient positioning on the treatment table. Women are treated in a supine treatment position on the Cyberknife radiosurgical flat tabletop.</li>
	<li>Discuss target and patient immobilization. Patient may undergo evacuated vacuum-bag immobilization to reduce intrafraction motion during radiation dose delivery. Once immobilized, women undergo non-contrasted contiguous axial CT high-resolution imaging (1 to 1 pitch, 1.0 mm slice thickness, voltage 120 kVp, 450 mAs).</li>
	<li>Discuss use of advanced imaging for target localization. After CT imaging, women undergo preferably conventional 18F-FDG PET/CT imaging in the same SBRT treatment position. Alternatively, women may undergo conventional contrasted pelvic magnetic resonance imaging.</li>
	<li>Describe image co-registration for radiosurgical treatment planning. Images from high-resolution CT and 18F-FDG PET/CT are imported for inverse radiation treatment planning on the MultiPlan 3.5.2 Treatment Planning System (Accuray).</li>
	<li>Describe team approach to radiosurgical treatment planning. For treatment planning, both a radiation oncologist and gynecologic oncologist contour cancer target clinical target volumes (CTVs). Other disease at-risk tissue is contoured and is included in CTVs. Nearby normal tissue structures such as the small bowel, rectum, bladder, liver, kidneys, lungs, bilateral proximal femurs, vagina, and sacral nerve roots are contoured by the radiation oncologist.</li>
	<li>Describe radiation dose prescription. A radiation prescription dose of 3 &times; 800 cGy = 2400 cGy (commonly to the 70% isodose line) has been selected. In a 200 cGy biological equivalent dose calculation, nearly 6170 cGy are delivered with this prescription assuming an "&alpha;/&beta;" ratio of 10 for tumor. The radiation emitted from a SBRT linear accelerator is collimated either by using one of 12 fixed tungsten circular collimators (5 to 60 mm) or by using a tungsten-copper alloy segmented hexagon IRIS collimator.14 Normal organs have a tolerance of radiation and use of dose-volume histogram parameters for normal tissue constraint during ablative stereotactic radiosurgery are listed in Table 1.</li>
</ol>
4. Stereotactic Cyberknife Radiosurgery Treatment Delivery
<ol>
	<li>Perform cross-plane image verification. During Cyberknife SBRT, soft-tissue fiducials (or in some cases rigid anatomical landmarks such as the skull for intracranial lesions and the spine for spine lesions) are tracked by cross-plane radiographic imaging and confirmed to be in the expected target location by the target localizing system (TLS) subsystem.</li>
	<li>Verify target positioning. Fiducials are tracked in three and up to six degrees of freedom (i.e., x, y, z, pitch, roll, and yaw). Images generated by the TLS are automatically registered and compared with digitally reconstructed radiographs (DRRs) generated from the initial treatment planning CT scan.</li>
	<li>Verify target positioning. If results of automatic registration indicate that fiducials have shifted beyond predefined tolerances in any one of the six degrees of freedom (x, y, z, pitch, roll, and yaw), treatment is automatically paused. Patient repositioning then occurs.</li>
	<li>Consider target motion. Targets that move with respiratory motion are treated utilizing the Synchrony Respiratory Tracking subsystem (Synchrony). With the use of a camera mounted in the treatment room, the system continuously tracks the patient's breathing pattern (i.e., obtain external position data) with the use of light-emitting diodes (LEDs) affixed to a vest around the patient's thorax.10 Together with the fiducial location information (internal position data) obtained from cross-plane x-rays, the Synchrony system builds a correlation model with the external data and the internal data. This correlation model allows the robotic arm to follow any respiratory-induced motion of the target while during the delivery of any and all treatment beams.</li>
	<li>Treatment may entail 100-150 deliverable treatment positions of the robotic arm. Treatments may last 30 to 90 minutes.</li>
</ol>
5. Representative Results
Stereotactic body radiation therapy (SBRT) may involve many individual radiation beams (blue vectors) all converging on single or multiple closely associated clinical radiation targets, as shown in Figure 1A. A representative good radiosurgical planning outcome gives a deliverable SBRT treatment with high radiation dose cancer target volume coverage and cancer target conformality. Figures 1B-D show 131 beams were used to treat on a pelvic relapse of a chemorefractory ovarian cancer target over 42 minutes. SBRT prescribed to the 80% isodose line rendered 100% clinical target volume coverage with a conformality index of 1.94 for a total dose of 2400 cGy in three daily 800 cGy fractions. The dose-volume histograms for the clinical target (red) and for the critical structures of rectum (brown), bladder (yellow), small bowel (light blue) sacral nerves (tan) and hips (orange) are depicted in Figure 2.
<img alt="Figure 1" src="/files/ftp_upload/3793/3793fig1.jpg" /> 
Figure 1. <a href="https://www.jove.com/files/ftp_upload/3793/3793fig1large.jpg" target="_blank">Click here to view larger figure</a>.
<img alt="Figure 2" src="/files/ftp_upload/3793/3793fig2.jpg" /> 
Figure 2. Dose-volume histograms for the clinical target (red) and for the critical structures of rectum (brown), bladder (yellow), small bowel (light blue) 
sacral nerves (tan) and hips (orange).

<ol>
	<li>Sherouse, G., Bourland, J., Reynolds, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Virtual+simulation+in+the+clinical+setting:+some+practical+considerations.">Virtual simulation in the clinical setting: some practical considerations.</a> Int. J. Radiat. Oncol. Biol. Phys. 19, 1059-1065 (1990).</li><li>Dickesn, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Personalized+fixation+using+a+vacuum+consolidation+technique.">Personalized fixation using a vacuum consolidation technique.</a> Br. J. Radiol. 54, 257-258 (1981).</li><li>Wunderink, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+of+respiratory+liver+tumor+motion+by+abdominal+compression+in+stereotactic+body+frame,+analyzed+by+tracking+fiducial+markers+implanted+in+liver.">Reduction of respiratory liver tumor motion by abdominal compression in stereotactic body frame, analyzed by tracking fiducial markers implanted in liver.</a> Int. J. Radiat. Oncol. Biol. Phys. 71, 907-915 (2008).</li><li>Mageras, G., Yorke, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deep+inspiration+breath+hold+and+respiratory+gating+strategies+for+reducing+organ+motion+in+radiation+treatments.">Deep inspiration breath hold and respiratory gating strategies for reducing organ motion in radiation treatments.</a> Semin. Radiat. Oncol. 14, 65-75 (2004).</li><li>Wong, J., Sharpe, M., Jaffray, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+active+breathing+control+(ABC)+to+reduce+margin+for+breathing+motion.">The use of active breathing control (ABC) to reduce margin for breathing motion.</a> Int. J. Radiat. Oncol. Biol. Phys. 44, 911-919 (1999).</li><li>Ford, E., Mageras, G., Yorke, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Respiration-correlated+spiral+CT:+a+method+of+measuring+respiratory-induced+anatomic+motion+for+radiation+treatment+planning.">Respiration-correlated spiral CT: a method of measuring respiratory-induced anatomic motion for radiation treatment planning.</a> Med. Phys. 30, 88-97 (2003).</li><li>Kunos, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyberknife+radiosurgery+for+squamous+cell+carcinoma+of+the+vulva+after+prior+pelvic+radiation+therapy.">Cyberknife radiosurgery for squamous cell carcinoma of the vulva after prior pelvic radiation therapy.</a> Technol. Cancer Res. Treat. 7, 375-380 (2008).</li><li>Kunos, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stereotactic+body+radiosurgery+for+pelvic+relapse+of+gynecologic+malignancies.">Stereotactic body radiosurgery for pelvic relapse of gynecologic malignancies.</a> Technol. Cancer Res. Treat. 8, 393-400 (2009).</li><li>Kilby, W., Dooley, J., Kuduvalli, G., Sayeh, S., Maurer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Cyberknife+robotic+radiosurgery+system+in+2010.">The Cyberknife robotic radiosurgery system in 2010.</a> Technol. Cancer Res. Treat. 9, 431-438 (2010).</li><li>Ozhasoglu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synchrony+&#x2013;+Cyberknife+Respiratory+Compensation+Technology.">Synchrony &#x2013; Cyberknife Respiratory Compensation Technology.</a> Med. Dosimetry. 33, 117-123 (2008).</li><li>Hoogeman, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+Accuracy+of+the+Respiratory+Tumor+Tracking+System+of+the+Cyberknife:+Assessment+By+Analysis+of+Log+Files.">Clinical Accuracy of the Respiratory Tumor Tracking System of the Cyberknife: Assessment By Analysis of Log Files.</a> Int. J. Radiat. Oncol. Biol. Phys. 74, 297-303 (2009).</li><li>Antypas, C., Pantelis, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performance+evaluation+of+a+CyberKnife+G4+image-guided+robotic+stereotactic+radiosurgery+system.">Performance evaluation of a CyberKnife G4 image-guided robotic stereotactic radiosurgery system.</a> Phys. Med. Biol. 53, 4697-4718 (2008).</li><li>Wilcox, E., Daskalov, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+GAFCHROMIC+EBT+film+for+Cyberknife+dosimetry.">Evaluation of GAFCHROMIC EBT film for Cyberknife dosimetry.</a> Med. Phys. 34, 1967-1974 (2007).</li><li>Echner, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+design,+physical+properties+and+clinical+utility+of+an+iris+collimator+for+robotic+radiosurgery.">The design, physical properties and clinical utility of an iris collimator for robotic radiosurgery.</a> Phys. Med. Biol. 54, 5359-5380 (2009).</li><li>Choi, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Image-guided+stereotactic+body+radiation+therapy+in+patients+with+isolated+para-aortic+lymph+node+metastases+from+uterine+cervical+and+corpus+cancer.">Image-guided stereotactic body radiation therapy in patients with isolated para-aortic lymph node metastases from uterine cervical and corpus cancer.</a> Int. J. Radiat. Oncol. Biol. Phys. 74, 147-153 (2009).</li></ol>

We (CAK, JMB, RD) have nothing to disclose.

Encouraging early SBRT outcomes have fueled clinical investigation of radiosurgery for treatment of persistent or recurrent gynecological cancers.7, 8, 15 Data question radiobiological effects and mode of cell death resulting from SBRT. Small clinical studies have shown that ablative radiation doses provided by SBRT produce targeted disease control rates exceeding 90%. Unlike with conventional radiation, it has been challenging to combine SBRT with radiosensitizing and cytotoxic/cytostatic chemotherapies. Better cancer targeting through increased planning treatment volume expansions and through inclusion of 18F-FDG PET/CT images has improved clinical outcomes. While it is imperative to look into other methods of delivering dose-escalated radiation with high precision, it remains undecided whether SBRT can provide equivalent therapeutic effectiveness as low and high dose-rate brachytherapy. Indeed, brachytherapy is the more commonly and validated technique to achieve radiation dose escalation in gynecologic cancer targets. As such, both enthusiasm and prudence are appropriate in reading available SBRT data for treatment of gynecologic cancers.

<table border="1">
 <tbody>
 <tr>
 <td>Name of the device</td>
 <td>Company</td>
 <td>Catalogue number</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>Cyberknife system</td>
 <td>Accuray (Sunnyvale, CA)</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 </tbody>
</table>

stereotactic radiosurgery for gynecologic cancer

Stereotactic body radiotherapy (SBRT) distinguishes itself by necessitating more rigid patient immobilization, accounting for respiratory motion, intricate treatment planning, on-board imaging, and reduced number of ablative radiation doses to cancer targets usually refractory to chemotherapy and conventional radiation. Steep SBRT radiation dose drop-off permits narrow 'pencil beam' treatment fields to be used for ablative radiation treatment condensed into 1 to 3 treatments.
Treating physicians must appreciate that SBRT comes at a bigger danger of normal tissue injury and chance of geographic tumor miss. Both must be tackled by immobilization of cancer targets and by high-precision treatment delivery. Cancer target immobilization has been achieved through use of indexed customized Styrofoam casts, evacuated bean bags, or body-fix molds with patient-independent abdominal compression.1-3 Intrafraction motion of cancer targets due to breathing now can be reduced by patient-responsive breath hold techniques,4 patient mouthpiece active breathing coordination,5 respiration-correlated computed tomography,6 or image-guided tracking of fiducials implanted within and around a moving tumor.7-9 The Cyberknife system (Accuray [Sunnyvale, CA]) utilizes a radiation linear accelerator mounted on a industrial robotic arm that accurately follows patient respiratory motion by a camera-tracked set of light-emitting diodes (LED) impregnated on a vest fitted to a patient.10 Substantial reductions in radiation therapy margins can be achieved by motion tracking, ultimately rendering a smaller planning target volumes that are irradiated with submillimeter accuracy.11-13
Cancer targets treated by SBRT are irradiated by converging, tightly collimated beams. Resultant radiation dose to cancer target volume histograms have a more pronounced radiation "shoulder" indicating high percentage target coverage and a small high-dose radiation "tail." Thus, increased target conformality comes at the expense of decreased dose uniformity in the SBRT cancer target. This may have implications for both subsequent tumor control in the SBRT target and normal tissue tolerance of organs at-risk. Due to the sharp dose falloff in SBRT, the possibility of occult disease escaping ablative radiation dose occurs when cancer targets are not fully recognized and inadequate SBRT dose margins are applied. Clinical target volume (CTV) expansion by 0.5 cm, resulting in a larger planning target volume (PTV), is associated with increased target control without undue normal tissue injury.7,8 Further reduction in the probability of geographic miss may be achieved by incorporation of 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET).8 Use of 18F-FDG PET/CT in SBRT treatment planning is only the beginning of attempts to discover new imaging target molecular signatures for gynecologic cancers.

Watch this Scientific Journal Video about Stereotactic Radiosurgery for Gynecologic Cancer at JoVE.com

Stereotactic Radiosurgery for Gynecologic Cancer

Stereotactic body radiotherapy (SBRT) involves image-guided, ablative radiation delivered to cancer targets refractory to chemotherapy or to conventional radiation treatment. The robotic-armed Cyberknife SBRT system, using sophisticated target localization, delivers hypofractionated radiation doses capable of sterilizing cancer targets. This article will consider new therapeutic roles of SBRT for gynecological cancers.

Stereotactic body radiotherapy (SBRT) distinguishes itself by necessitating more rigid patient immobilization, accounting for respiratory motion, ...

stereotactic-radiosurgery-for-gynecologic-cancer

Research

JoVE Journal

Medicine

17.5K Views.  University Hospitals Case Medical Center and Case Western Reserve University School of Medicine. Stereotactic body radiotherapy (SBRT) involves image-guided, ablative radiation delivered to cancer targets refractory to chemotherapy or to conventional radiation treatment. The robotic-armed Cyberknife SBRT system, using sophisticated target localization, delivers hypofractionated radiation doses capable of sterilizing cancer targets. This article will consider new therapeutic roles of SBRT for gynecological cancers.

Video: Stereotactic Radiosurgery for Gynecologic Cancer

Multispectral Real-time Fluorescence Imaging for Intraoperative Detection of the Sentinel Lymph Node in Gynecologic Oncology

The prognosis in virtually all solid tumors depends on the presence or absence of lymph node metastases.1-3 Surgical treatment most often combines radical excision of the tumor with a full lymphadenectomy in the drainage area of the tumor. However, removal of lymph nodes is associated with increased morbidity due to infection, wound breakdown and lymphedema.4,5 As an alternative, the sentinel lymph node procedure (SLN) was developed several decades ago to detect the first draining lymph node from the tumor.6 In case of lymphogenic dissemination, the SLN is the first lymph node that is affected (Figure 1). Hence, if the SLN does not contain metastases, downstream lymph nodes will also be free from tumor metastases and need not to be removed. The SLN procedure is part of the treatment for many tumor types, like breast cancer and melanoma, but also for cancer of the vulva and cervix.7 The current standard methodology for SLN-detection is by peritumoral injection of radiocolloid one day prior to surgery, and a colored dye intraoperatively. Disadvantages of the procedure in cervical and vulvar cancer are multiple injections in the genital area, leading to increased psychological distress for the patient, and the use of radioactive colloid.
Multispectral fluorescence imaging is an emerging imaging modality that can be applied intraoperatively without the need for injection of radiocolloid. For intraoperative fluorescence imaging, two components are needed: a fluorescent agent and a quantitative optical system for intraoperative imaging. As a fluorophore we have used indocyanine green (ICG). ICG has been used for many decades to assess cardiac function, cerebral perfusion and liver perfusion.8 It is an inert drug with a safe pharmaco-biological profile. When excited at around 750 nm, it emits light in the near-infrared spectrum around 800 nm. A custom-made multispectral fluorescence imaging camera system was used.9.
The aim of this video article is to demonstrate the detection of the SLN using intraoperative fluorescence imaging in patients with cervical and vulvar cancer. Fluorescence imaging is used in conjunction with the standard procedure, consisting of radiocolloid and a blue dye. In the future, intraoperative fluorescence imaging might replace the current method and is also easily transferable to other indications like breast cancer and melanoma.

Fluorescence imaging is a promising innovative modality for image-guided surgery in surgical oncology. In this video we describe the technical procedure for detection of the sentinel lymph node using fluorescence imaging as showcased in gynecologic oncologicy. A multispectral fluorescence camera system, together with the fluorescent agent indocyanine green, is applied.

The prognosis in virtually all solid tumors depends on the presence or absence of lymph node metastases.1-3 Surgical treatment most often combines radical ...

Stereotactic Intracranial Implantation and In vivo Bioluminescent Imaging of Tumor Xenografts in a Mouse Model System of Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is a high-grade primary brain cancer with a median survival of only 14.6 months in humans despite standard tri-modality treatment consisting of surgical resection, post-operative radiation therapy and temozolomide chemotherapy 1. New therapeutic approaches are clearly needed to improve patient survival and quality of life. The development of more effective treatment strategies would be aided by animal models of GBM that recapitulate human disease yet allow serial imaging to monitor tumor growth and treatment response. In this paper, we describe our technique for the precise stereotactic implantation of bio-imageable GBM cancer cells into the brains of nude mice resulting in tumor xenografts that recapitulate key clinical features of GBM 2. This method yields tumors that are reproducible and are located in precise anatomic locations while allowing in vivo bioluminescent imaging to serially monitor intracranial xenograft growth and response to treatments 3-5. This method is also well-tolerated by the animals with low perioperative morbidity and mortality.

Stereotactic Intracranial Implantation and In vivo Bioluminescent Imaging of Tumor Xenografts in a Mouse Model System of Glioblastoma Multiforme

We describe an integrated method for the precise, stereotactic implantation of human glioblastoma multiforme cells into the brains of nude mice and subsequent serial in vivo imaging to monitor growth and response to treatment of the resultant xenografts.

Glioblastoma multiforme (GBM) is a high-grade primary brain cancer with a median survival of only 14.6 months in humans despite standard tri-modality ...

Cerenkov Luminescence Imaging (CLI) for Cancer Therapy Monitoring

In molecular imaging, positron emission tomography (PET) and optical imaging (OI) are two of the most important and thus most widely used modalities1-3. PET is characterized by its excellent sensitivity and quantification ability while OI is notable for non-radiation, relative low cost, short scanning time, high throughput, and wide availability to basic researchers. However, both modalities have their shortcomings as well. PET suffers from poor spatial resolution and high cost, while OI is mostly limited to preclinical applications because of its limited tissue penetration along with prominent scattering optical signals through the thickness of living tissues.
 Recently a bridge between PET and OI has emerged with the discovery of Cerenkov Luminescence Imaging (CLI)4-6. CLI is a new imaging modality that harnesses Cerenkov Radiation (CR) to image radionuclides with OI instruments. Russian Nobel laureate Alekseyevich Cerenkov and his colleagues originally discovered CR in 1934. It is a form of electromagnetic radiation emitted when a charged particle travels at a superluminal speed in a dielectric medium7,8. The charged particle, whether positron or electron, perturbs the electromagnetic field of the medium by displacing the electrons in its atoms. After passing of the disruption photons are emitted as the displaced electrons return to the ground state. For instance, one 18F decay was estimated to produce an average of 3 photons in water5. 
 Since its emergence, CLI has been investigated for its use in a variety of preclinical applications including in vivo tumor imaging, reporter gene imaging, radiotracer development, multimodality imaging, among others4,5,9,10,11. The most important reason why CLI has enjoyed much success so far is that this new technology takes advantage of the low cost and wide availability of OI to image radionuclides, which used to be imaged only by more expensive and less available nuclear imaging modalities such as PET.
 Here, we present the method of using CLI to monitor cancer drug therapy. Our group has recently investigated this new application and validated its feasibility by a proof-of-concept study12. We demonstrated that CLI and PET exhibited excellent correlations across different tumor xenografts and imaging probes. This is consistent with the overarching principle of CR that CLI essentially visualizes the same radionuclides as PET. We selected Bevacizumab (Avastin; Genentech/Roche) as our therapeutic agent because it is a well-known angiogenesis inhibitor13,14. Maturation of this technology in the near future can be envisioned to have a significant impact on preclinical drug development, screening, as well as therapy monitoring of patients receiving treatments.

Cerenkov Luminescence Imaging CLI for Cancer Therapy Monitoring

Use of Cerenkov Luminescence Imaging (CLI) for monitoring preclinical cancer treatment is described here. This method takes advantage of Cerenkov Radiation (CR) and optical imaging (OI) to visualize radiolabeled probes and thus provides an alternative to PET in preclinical therapeutic monitoring and drug screening.

In  molecular imaging, positron emission tomography (PET) and optical imaging (OI)  are two of the most important and thus most widely used modalities1-3. ...

Bioluminescent Orthotopic Model of Pancreatic Cancer Progression

Pancreatic cancer has an extremely poor five-year survival rate of 4-6%. New therapeutic options are critically needed and depend on improved understanding of pancreatic cancer biology. To better understand the interaction of cancer cells with the pancreatic microenvironment, we demonstrate an orthotopic model of pancreatic cancer that permits non-invasive monitoring of cancer progression. Luciferase-tagged pancreatic cancer cells are resuspended in Matrigel and delivered into the pancreatic tail during laparotomy. Matrigel solidifies at body temperature to prevent leakage of cancer cells during injection. Primary tumor growth and metastasis to distant organs are monitored following injection of the luciferase substrate luciferin, using in vivo imaging of bioluminescence emission from the cancer cells. In vivo imaging also may be used to track primary tumor recurrence after resection. This orthotopic model is suited to both syngeneic and xenograft models and may be used in pre-clinical trials to investigate the impact of novel anti-cancer therapeutics on the growth of the primary pancreatic tumor and metastasis.

Improved understanding of pancreatic cancer biology is critically needed to enable the development of better therapeutic options to treat pancreatic cancer. To address this need, we demonstrate an orthotopic model of pancreatic cancer that permits non-invasive monitoring of cancer progression using in vivo bioluminescence imaging.

Pancreatic cancer has an extremely poor five-year survival rate of 4-6%.  New therapeutic options are critically needed and depend on improved ...

Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells

Estrogen plays vital roles in mammary gland development and breast cancer progression. It mediates its function by binding to and activating the estrogen receptors (ERs), ER&#945;, and ER&#946;. ER&#945; is frequently upregulated in breast cancer and drives the proliferation of breast cancer cells. The ERs function as transcription factors and regulate gene expression. Whereas ER&#945;&#39;s regulation of protein-coding genes is well established, its regulation of noncoding microRNA (miRNA) is less explored. miRNAs play a major role in the post-transcriptional regulation of genes, inhibiting their translation or degrading their mRNA. miRNAs can function as oncogenes or tumor suppressors&#160;and are also promising biomarkers. Among the miRNA assays available, microarray and quantitative real-time polymerase chain reaction (qPCR) have been extensively used to detect and quantify miRNA levels. To identify miRNAs regulated by estrogen signaling in breast cancer, their expression in ER&#945;-positive breast cancer cell lines were compared before and after estrogen-activation using both the &#181;Paraflo-microfluidic microarrays and Dual Labeled Probes-low density arrays. Results were validated using specific qPCR assays, applying both Cyanine dye-based and Dual Labeled Probes-based chemistry. Furthermore, a time-point assay was used to identify regulations over time. Advantages of the miRNA assay approach used in this study is that it enables a fast screening of mature miRNA regulations in numerous samples, even with limited sample amounts. The layout, including the specific conditions for cell culture and estrogen treatment, biological and technical replicates, and large-scale screening followed by in-depth confirmations using separate techniques, ensures a robust detection of miRNA regulations,&#160;and eliminates false positives and other artifacts. However, mutated or unknown miRNAs, or regulations at the primary and precursor transcript level, will not be detected. The method presented here represents a thorough investigation of estrogen-mediated miRNA regulation.

Molecular signaling through both estrogen and microRNAs are critical in breast cancer development and growth. Estrogen activates the estrogen receptors, which are transcription factors. Many transcription factors can regulate the expression of microRNAs, and estrogen-regulated microRNAs can be profiled using different large-scale techniques.

Estrogen plays vital roles in mammary gland development and breast cancer progression. It mediates its function by binding to and activating the estrogen ...

Utilizing Murine Inducible Telomerase Alleles in the Studies of Tissue Degeneration/Regeneration and Cancer

Telomere dysfunction-induced loss of genome integrity and its associated DNA damage signaling and checkpoint responses are well-established drivers that cause tissue degeneration during ageing. Cancer, with incidence rates greatly increasing with age, is characterized by short telomere lengths and high telomerase activity. To study the roles of telomere dysfunction and telomerase reactivation in ageing and cancer, the protocol shows how to generate two murine inducible telomerase knock-in alleles 4-Hydroxytamoxifen (4-OHT)-inducible TERT-Estrogen Receptor (mTERT-ER) and Lox-Stopper-LoxTERT (LSL-mTERT). The protocol describes the procedures to induce telomere dysfunction and reactivate telomerase activity in mTERT-ER and LSL-mTERT mice in vivo. The representative data show that reactivation of telomerase activity can ameliorate the tissue degenerative phenotypes induced by telomere dysfunction. In order to determine the impact of telomerase reactivation on tumorigenesis, we generated prostate tumor model G4 PB-Cre4 PtenL/L p53L/L LSL-mTERTL/L and thymic T-cell lymphoma model G4 Atm-/- mTERTER/ER. The representative data show that telomerase reactivation in the backdrop of genomic instability induced by telomere dysfunction can greatly enhance tumorigenesis. The protocol also describes the procedures used to isolate neural stem cells (NSCs) from mTERT-ER and LSL-mTERT mice and reactivate telomerase activity in NSCs in vitro. The representative data show that reactivation of telomerase can enhance the self-renewal capability and neurogenesis in vitro. Finally, the protocol describes the procedures for performing telomere FISH (Fluorescence In Situ Hybridization) on both mouse FFPE (Formalin Fixed and Paraffin Embedded) brain tissues and metaphase chromosomes of cultured cells.

Telomere and telomerase play essential roles in ageing and tumorigenesis. The goal of this protocol is to show how to generate two murine inducible telomerase knock-in alleles and how to utilize them in the studies of tissue degeneration/regeneration and cancer.

Telomere dysfunction-induced loss of genome integrity and its associated DNA damage signaling and checkpoint responses are well-established drivers that ...

Studying Pancreatic Cancer Stem Cell Characteristics for Developing New Treatment Strategies

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor initiation, metastasis and resistance to radio- and chemotherapy. Here we describe a specific methodology for culturing primary human pancreatic CSCs as tumor spheres in anchorage-independent conditions. Cells are grown in serum-free, non-adherent conditions in order to enrich for CSCs while their more differentiated progenies do not survive and proliferate during the initial phase following seeding of single cells. This assay can be used to estimate the percentage of CSCs present in a population of tumor cells. Both size (which can range from 35 to 250 micrometers) and number of tumor spheres formed represents CSC activity harbored in either bulk populations of cultured cancer cells or freshly harvested and digested tumors 1,2. Using this assay, we recently found that metformin selectively ablates pancreatic CSCs; a finding that was subsequently further corroborated by demonstrating diminished expression of pluripotency-associated genes/surface markers and reduced in vivo tumorigenicity of metformin-treated cells. As the final step for preclinical development we treated mice bearing established tumors with metformin and found significantly prolonged survival. Clinical studies testing the use of metformin in patients with PDAC are currently underway (e.g., NCT01210911, NCT01167738, and NCT01488552). Mechanistically, we found that metformin induces a fatal energy crisis in CSCs by enhancing reactive oxygen species (ROS) production and reducing mitochondrial transmembrane potential. In contrast, non-CSCs were not eliminated by metformin treatment, but rather underwent reversible cell cycle arrest. Therefore, our study serves as a successful example for the potential of in vitro sphere formation as a screening tool to identify compounds that potentially target CSCs, but this technique will require further in vitro and in vivo validation to eliminate false discoveries.

Pancreatic cancer stem cells (CSCs) can be expanded in vitro using the anchorage-independent sphere culture technique, which represents a powerful tool to study CSC biology and can serve as the first step to develop novel CSC-targeting therapies. Here the methodology for expanding, analyzing and targeting of pancreatic CSCs is provided.

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor ...

Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy

Physicians considering stereotactic ablative body radiation therapy (SBRT) for the treatment of extracranial cancer targets must be aware of the sizeable risks for normal tissue injury and the hazards of physical tumor miss. A first-of-its-kind SBRT platform achieves high-precision ablative radiation treatment through a combination of versatile real-time imaging solutions and sophisticated tumor tracking capabilities. It uses dual-diagnostic kV x-ray units for stereoscopic open-loop feedback of cancer target intrafraction movement occurring as a consequence of respiratory motions and heartbeat. Image-guided feedback drives a gimbaled radiation accelerator (maximum 15 x 15 cm field size) capable of real-time &#177;4 cm pan-and-tilt action. Robot-driven &#177;60&#176; pivots of an integrated &#177;185&#176; rotational gantry allow for coplanar and non-coplanar accelerator beam set-up angles, ultimately permitting unique treatment degrees of freedom. State-of-the-art software aids real-time six dimensional positioning, ensuring irradiation of cancer targets with sub-millimeter accuracy (0.4 mm at isocenter). Use of these features enables treating physicians to steer radiation dose to cancer tumor targets while simultaneously reducing radiation dose to normal tissues. By adding respiration correlated computed tomography (CT) and 2-[18F] fluoro-2-deoxy-&#7429;-glucose (18F-FDG) positron emission tomography (PET) images into the planning system for enhanced tumor target contouring, the likelihood of physical tumor miss becomes substantially less1. In this article, we describe new radiation plans for the treatment of moving lung tumors.

Stereotactic ablative body radiation therapy (SBRT) involves the precise delivery of high-dose radiation to cancer tumor targets. A novel SBRT platform offers a first-of-its-kind gimbaled radiation accelerator mounted within a pivoting O-ring gantry capable of dynamic image-guided tumor tracking. Here, we describe dynamic tumor tracking for lung targets.

Physicians considering stereotactic ablative body radiation therapy (SBRT) for the treatment of extracranial cancer targets must be aware of the sizeable ...

Working with Human Tissues for Translational Cancer Research

Medical research for human benefit is greatly impeded by the necessity for human tissues and subjects. However, upon obtaining consent for human specimens, precious samples must be handled with the greatest care in order to ensure integrity of organs, tissues, and cells to the highest degree. Unfortunately, tissue processing by definition requires extraction of tissues from the host, a change which can cause great cellular stress and have major repercussions on subsequent analyses. These stresses could result in the specimen being no longer representative of the site from which it was retrieved. Therefore, a strict protocol must be adhered to while processing these specimens to ensure representativeness. The desired assay(s) must also be taken into consideration in order to ensure that an optimal technique is used for sample processing. Outlined here is a protocol for tissue retrieval, processing and various analyses which may be performed on processed tissue in order to maximize downstream production from limited tissue samples.

Translational cancer research is dependent on extraction of human tissues. Much work has gone into optimizing extraction methods for ex vivo analysis. Here, we describe tissue processing methods allowing for maximal data output from limited samples.

Medical research for human benefit is greatly impeded by the necessity for human tissues and subjects. However, upon obtaining consent for human ...

Modeling the Early Steps of Ovarian Cancer Dissemination in an Organotypic Culture of the Human Peritoneal Cavity

The pattern of ovarian cancer metastasis is markedly different from that of most other epithelial tumors, because it rarely spreads hematogenously. Instead, ovarian cancer cells exfoliated from the primary tumor are carried by peritoneal fluid to metastatic sites within the peritoneal cavity. These sites, most notably the abdominal peritoneum and omentum, are organs covered by a mesothelium-lined surface. To investigate the processes of ovarian cancer dissemination, we assembled a complex three-dimensional culture system that reconstructs the lining of the peritoneal cavity in vitro. Primary human fibroblasts and mesothelial cells were isolated from human omentum. The fibroblasts were then mixed with extracellular matrix and covered with a layer of the primary human mesothelial cells to mimic the peritoneal and omental surfaces encountered by metastasizing ovarian cancer cells. The resulting organotypic model is, as shown, used to examine the early steps of ovarian cancer dissemination, including cancer cell adhesion, invasion, and proliferation. This model has been used in a number of studies to investigate the role of the microenvironment (cellular and acellular) in early ovarian cancer dissemination. It has also been successfully adapted to high throughput screening and used to identify and test inhibitors of ovarian cancer metastasis.

Here, we present a protocol to construct a three-dimensional in vitro model of the lining of the peritoneal cavity, composed of primary human mesothelial cells and fibroblasts layered with extracellular matrix, as a tool to investigate ovarian cancer cell adhesion, invasion, and proliferation.

The pattern of ovarian cancer metastasis is markedly different from that of most other epithelial tumors, because it rarely spreads hematogenously. ...