Randomized clinical trial comparing level II and level III axillary node dissection in addition to mastectomy for breast cancer

Abstract

Abstract Background In addition to mastectomy, level II and level III axillary node dissection procedures are performed widely in Japan. A randomized clinical trial was performed to determine which procedure was more effective. Methods One group of women had resection of the pectoralis minor muscle and dissection of level I, II and III axillary lymph nodes (level III dissection). In a second group, the pectoralis minor muscle was left intact and level III axillary lymph node dissection was not performed (level II dissection). A total of 1209 women with stage II breast cancer were enrolled in the study and randomly assigned to one of the two groups. Results The 10-year cumulative survival rate was 86·6 per cent after level II and 85·7 per cent after level III axillary dissection (hazard ratio (HR) 1·02; P = 0·931, log rank test). The 10-year disease-free survival rate was 73·3 and 77·8 per cent respectively (HR 0·94, P = 0·666). Overall survival and disease-free survival rates in the two groups were similar after both procedures. The duration of surgery was significantly shorter (P < 0·001) and blood loss was significantly less (P = 0·001) after level II dissection. In a survey of patients' symptoms on follow-up, no significant differences were found between the two procedures. Conclusion The addition of pectoralis minor muscle resection and level III axillary lymph node dissection to mastectomy for stage II breast cancer did not improve overall or disease-free survival rates.