The role of the regional lymph node in breast cancer: a comparison between nodal and systemic reactivity.

Confusion remains concerning the role of the regional lymph node in the containment of cancer. Numerous investigators using a variety of assays have reported often conflicting results concerning the immunocompetency of lymphocytes residing in regional nodes. Forty-two axillary lymph nodes from ten stage I and stage II breast cancer patients were studied in lymphocyte blast assays using mitogens and breast cancer antigen (BCA). Three general response patterns to BCA were identified which were related primarily to tumor size. In the patients with the smallest primary tumor (0.5 cm), lymphocytes in the nodes reacted to a much greater extent than peripheral blood lymphocytes (PBL). In two of three patients with intermediate-size tumor (1.0 to 1.5 cm), a mixed pattern of responses was seen with both stimulation suppression occurring within the nodes of the same patient. In the four patients with the largest tumors (2.0 to 3.0 cm), 15 of 19 nodes had a lower stimulation index (SI) than the corresponding PBL. From the results of this study it appears that regional lymph nodes are dynamic immunologic structures which regress in responsiveness as tumor burden increases.