Primary tumor response to induction chemotherapy as a predictor of histological status of axillary nodes in operable breast cancer patients

Background: Routine use of axillary lymph node dissection is being question ed, especially in clinically N0 patients. The goal of this study was to det ermine whether primary tumor response to induction chemotherapy (IC) can pr edict the histological volume of residual axillary disease in patients who were candidates for breast conservation surgery after IC. Methods: Forty-seven patients with stage II or IIIA breast cancer who recei ved breast conservation surgery were selected from a population of patients randomized to receive four cycles of IC. Largest clinical tumor size befor e and after IC was determined by physical examination, mammography, and bre ast ultrasound. Clinical nodal status was determined by physical examinatio n and axillary ultrasound and compared with histological findings. Results: In patients with at least 50% reduction in primary tumor size afte r IC, 12 of 14 (86%) N0 patients and 11 of 17 (65%) N1 patients were histol ogically negative. In patients with a less than 50% reduction, 0 of 3 N0 pa tients and 2 of 13 (15%) N1 patients were histologically negative. Conclusions: There is significantly less axillary disease in responders tha n in nonresponders after IC. For N0 responders, axillary irradiation may be an acceptable alternative to axillary lymph node dissection, and could eas ily be incorporated into the postsurgical radiotherapy that is standard pro tocol for breast conservation therapy. The more aggressive disease in nonre sponders is best treated by axillary lymph node dissection, pending further study.