Radical Mastectomy: Surgical Removal of the Entire Mammary Gland from a Mouse to Study Cancer Progression

Radical mastectomy is a procedure of surgically removing the entire mammary gland with the underlying chest muscle and axillary lymph nodes. First, anesthetize a mouse with an appropriate amount of isoflurane. Place the mouse on a surgical bed and inject buprenorphine, an anesthetic, to reduce pain subcutaneously into its shoulder.

Next, insert the nose of the mouse into a nose mask to provide a continuous supply of oxygen and isoflurane, another anesthetic, to the animal. Using some lab tape, restrain the animal's limbs and sterilize the chest skin with chlorhexidine, iodine, and ethanol.

Next, use microscissors to make a vertical incision near the tumor in the middle of the anterior chest wall. Extend the incision to the axillary lymph nodes present at the root of the fore limb. Lift the skin with forceps to resect the tumor and lymph nodes off the chest wall using scissors. Use sterile sutures to stitch the skin closed. Return the animal to a cage and monitor until it recovers completely. In the example protocol, we will perform a radical mastectomy to remove the primary tumor from an adult mouse.

To perform the mastectomy, eight days after cancer inoculation, prepare the mouse for surgery as just demonstrated and make a 5 millimeter skin incision, 2 millimeters to the left of the surgical scar from the cancer cell inoculation.

Extend the incision toward the root of the forelimb to remove the tumor, and the skin including the surgical scar, and the lesion in contact with the tumor, and the axillary lymph node basin in which typically, no visible lymph nodes are present at the time of the mastectomy. Then close the skin defects with sterile 5-0 non-absorbable sutures in the shape of a Y. And return the animal to its cage with monitoring until full recumbency.