The effectiveness of prophylactic subcutaneous mastectomy in Sprague-Dawley rats induced with...

Fifty-day-old female, albino Sprague-Dawley rats were induced with DMBA, a potent carcinogen that reliably causes multiple breast tumors. Prophylactic subcutaneous mastectomy was performed 2 weeks after injection. Control animals had no breast tissue removed and developed 5.14 tumors per animal, or 1.3 tumors per quadrant. Animals subjected to 50 percent (unilateral) mastectomy developed 5.4 tumors per animal, with 0.72 tumors per surgical quadrant. Animals that underwent 75 percent (three quadrant) mastectomy developed 4.33 tumors per animal, or 0.48 tumors per surgical quadrant. The incidence of tumors was significantly reduced in the surgical areas. However, the risk of any animal developing a breast neoplasm was not reduced in direct proportion to the percentage of breast tissue removed. We believe that this model may prove valuable in evaluating prophylactic subcutaneous mastectomy.