The contribution of regional lymph nodes in the resistance against breast cancer: practical implications.

Experimental evidence suggests that regional lymph nodes (RLN) are important in the initiation and possibly the maintenance of tumor immunity. "Negative" nodes denote strong tumor immunity and "positive" nodes low. The latter also serve as markers of systemic disease. From histological and immunological studies, and mostly from recent clinical studies in breast cancer, the following practical recommendations are made: (1) Clinically positive axillary nodes are best eliminated by surgery. (2) Resection of positive internal mammary nodes appears to increase survival of patients with central and inner quadrant lesions; however, destruction of these nodes by irradiation, although improving local disease control, may decrease survival. (3) Negative RLN should be preserved, as they appear to prevent lymph node metastases and stimulate systemic immunity. Only a small fraction of unresected RLN harboring micrometastases will ultimately develop palpable disease, and their elimination at that late phase yields the same results as when these nodes are treated prophylactically.