The Application of 1% Methylene Blue Dye As a Single Technique in Breast Cancer Sentinel Node Biopsy

Summary

In Indonesia, sentinel node biopsy (SNB) is not routinely performed for breast cancer surgery because of the limitation to provide radioisotope tracer and isosulfan or patent blue dye (PBD). To overcome this obstacle, we applied 1% methylene blue dye (MBD) as a single agent to map the sentinel nodes (SNs).

Abstract

In this study, we injected 1% methylene blue dye (MBD) into the subareolar or peritumoral space of the breast. In the case of breast conserving surgery (BCS), a separate incision in the lower axilla hairline was made to find the sentinel nodes (SNs). In mastectomy, the SNs were identified through the same mastectomy incision. The SNs were described as blue nodes or nodes with lymphatic blue channels. An anatomical landmark in the axilla was used to facilitate SNs identification. The SNs metastases were evaluated by intraoperative frozen section analysis and histopathology examination as it is a gold standard. Here, we described the MBD as the lone technique in breast cancer sentinel node biopsy (SNB) which could be useful when radioisotope tracer or patent or isosulfan blue dye (PBD) cannot be provided.

Introduction

The status of axillary lymph nodes (ALNs) metastasis is the most important prognostic factor in breast cancer. Axillary lymph node dissection (ALND) was the conventional procedure to assess metastatic status of ALNs^1,2. Unfortunately, ALND results in morbidities to the patients which decreases the quality of life, especially by increasing the risk of lymphedema after this procedure^3,4. Nowadays, sentinel node biopsy (SNB) has replaced ALND for axillary staging because of its minimal morbidities among patients⁵. The most common method for performing SNB is using radioisotope tracer and PBD⁶. In some parts of the world, including in developing countries, these tracer agents could be difficult to procure and searching for an alternative tracer agent is critical to solve the problem.

Initially, MBD was used by Wong et al. as a tracer agent for mapping sentinel nodes (SNs)⁷. In their study using a feline model, intradermal injection of MBD showed poor lymphatic uptake and isosulfan blue was chosen as the preferred dye for sentinel node (SN) mapping⁷. Methylene blue dye has been used in breast cancer SNB since the first successful report by Simmons et al.⁸. Several studies have also reported MBD as the favorable dye for SNs identification, and that the false negative rates of MBD technique were comparable to radioisotope or PBD^9,10,11. Fewer allergic reactions and lower price are the other reasons to consider its use in SN mapping¹².

Recently, we studied the use of 1% MBD alone for SNB in clinically node negative breast cancer. In early stages, MBD has a favorable identification rate and negative predictive value¹³. We inject 2 mL of 1% MBD into the subareolar space or peritumoral area if there was an excisional biopsy scar at the upper outer quadrant or nipple areolar complex (NAC) of the breast. The blue nodes and non-blue nodes with lymphatic blue channels are categorized as SNs. The anatomical landmark in the axilla is used as a guidance to find SNs. Intraoperative examination is applied to assess the metastasis and the SNs are sent for histopathology analysis based on American Society of Clinical Oncology (ASCO) Guidelines¹⁴.

If the cases are selected carefully and the skills required for this technique are obtained by the surgeons as well as pathologists, many patients could be saved from the harmful effects of ALND while still having favorable survival.

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Protocol

All procedures including human subjects have been approved by Dharmais Cancer Hospital Ethics Committee with certificate number of 040/KEPK/VII/2017. All patients signed the consent forms and expressed agreement to participate in this study.

NOTE: The inclusion criteria are patients with diagnosis of early breast cancer, with tumor stage T1-T2 without palpable and ultrasonography lymph nodes enlargement (cNo). The exclusion criteria are locally advanced breast cancer, received neo adjuvant chemo or hormonal therapy, and pregnancy.

1. Preparation of 1% methylene blue dye and the injection technique

1. Sterilize the surgical field after anesthetizing the patient.
2. Aspirate 2 mL of 1% methylene blue dye from its vial with a 3 mL syringe.
3. Draw a line to mark the lower axillary hairline below the lateral border of pectoralis major muscle.
4. Inject 2 mL of 1% methylene blue dye into the subareolar space of the breast.
5. If there is a scar in the upper outer quadrant of the breast or NAC, inject 2 mL of 1% methylene blue dye peritumorally into the breast parenchyma at the lateral side of the scar towards the axilla with a 23G needle under ultrasound guidance with a linear probe (12 MHz).
6. Massage the breast circularly at the injection site for 5 min, and then continue to perform surgery.

2. Sentinel node biopsy technique in breast conserving surgery (BCS)

NOTE: The surgery is performed in a patient who underwent BCS and SNB.

1. Prepare the surgical tools: monopolar electrocautery, DeBakey forceps/anatomical forceps, and retractors.
2. Incise the skin, subcutaneous tissue, and fascia.
3. Find the blue nodes or blue lymphatic tracts. Follow the blue tracts until the blue nodes or non-blue nodes with lymphatic blue tracts are identifiable.
4. Search for the sentinel nodes along the intercostobrachial nerve and lateral thoracic vein if the blue nodes or blue lymphatic tracts cannot be found.
5. Resect the sentinel nodes carefully and avoid damaging the nodes.
6. Palpate the axillary space to find additional suspicious malignant lymph node enlargement.

3. Sentinel node biopsy technique in mastectomy

NOTE: The surgery is done in a patient who underwent mastectomy and SNB.

1. Incise the skin and subcutaneous tissue.
2. Create skin flaps.
3. Remove the breast from pectoralis major until axillary fossa can be fully exposed.
4. Incise the clavicopectoral fascia to find the sentinel node.
5. If the blue lymphatic tracts cannot be found, find the sentinel node along the intercostobrachial nerve and lateral thoracic vein area.
6. Remove the sentinel node.
7. Look for additional suspicious lymph nodes by palpation.

4. Intraoperative examination

1. Slice the lymph nodes no thicker than 2 mm, parallel to the long axis.
2. Make touch imprint cytology from each node.
3. Place the surgical specimen on a metal tissue disc and embed in a gel-like medium with the same density as frozen tissue.
4. Submit all of the nodes for frozen section (FS) examination.
5. Categorize the metastatic status of sentinel nodes into positive or negative, and report it to the surgeon during the surgery.

5. Pathological examination

1. Perform the final pathologic evaluation of the sentinel nodes on formalin-fixed and paraffin-embedded tissue sections.
2. Classify the sentinel nodes metastasis according to the 6^th edition of American Joint Committee on Cancer (AJCC) manual. Macrometastasis (MAC) is defined as tumor deposits larger than 2 mm, micrometastasis (MiC) is defined as tumor deposits between 0.2 and 2 mm, isolated tumor cells (ITC) are defined as cell clusters no larger than 0.2 mm.
3. Perform the serial sectioning and immunohistochemistry analysis for cytokeratin when there are doubts over defining ITC.
4. Examine the rest of axillary lymph nodes in a similar manner.

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Results

Here, we describe the results from the presented technique. Two milliliters of 1% MBD were injected at the deep subareolar space as the standard technique of injection (Figure 1A). If the peritumoral injection is indicated, it should be performed under ultrasound guidance (Figure 1B). The blue nodes or lymphatic blue tracts were seen after entering the axillary space. Following the lymphatic blue tracts lead to finding the SNs (<...

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Discussion

In the modern era of breast cancer surgery, SNB has replaced ALND as the standard of care for axillary staging in early breast cancer and ALND should be abandoned if the SNs are free from metastasis^14,15. The lymphatic mapping technique which is commonly used in developed countries is the application of radioisotope tracer and PBD as a combined or single technique^16,17. The question on how to perform SNB ...

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Materials

Name	Company	Catalog Number	Comments
Metiblo 50mg/5ml	Laboratories Sterop NV	BE475217	Methylene Blue Dye
Disposable syringe with needle - 3mL (Luer Lock Tip)	Terumo Europe NV	dvr-3414	Syringe for Injection
ForceTriad energy platform	Medtronic	ForceTriad	Surgical cautery
Shandon Cryomatrix embedding resin	Thermo (scientific)	6769006	Frozen Section
Cryotome FSE	Thermo (scientific)	77210153
HistoStar Embedding Workstation	Thermo (scientific)	A81000001	Histopathological Examination
Finesse Me+	Thermo (scientific)	A77510272
Gemini AS	Thermo (scientific)	A81500002
Benchmark GX	Ventana Medical Systems	750-850	Immunohistochemistry
Benchmark XT	Ventana Medical Systems	750-700
Microscope	Olympus	Model BX53
Ultrasound	Phillips	HD 7XE