Comprehensive review of the management of internal mammary lymph node metastases in breast cancer.

Abstract

At the suggestion of Sampson Handley, Philip Stibbe, in 1918, characterized the spread of breast cancer to the internal mammary lymph node (IMN) chain as a pattern of metastasis. In 1952, Wangensteen published the technique of extended radical mastectomy. This technique, developed in an attempt to increase local control and survival in breast cancer, combined the classic radical mastectomy with resection of the IMN chain from the fifth intercostal space to the base of the neck. Early investigations in the 1960s and 1970s focused on the significance of IMN metastases, but the extended radical mastectomy was subsequently abandoned when prospective, randomized trials failed to demonstrate a significant increase in survival. The resurgence in interest in IMN metastases seen over the last several years is a result of the advent of lymphatic mapping and sentinel lymph node (SLN) biopsy. Lymphoscintigrams show mapping to internal mammary lymph nodes in up to 35% of patients, a finding that raises questions about the role for internal mammary sentinel lymph node (IM SLN) biopsy. In an attempt to formulate guidelines for the management of IM SLNs, we critically reviewed the historical and new evidence concerning the significance of IMN metastases. In this article, we evaluate the incidence of IMN metastases, the effect of IMN metastases on survival, the effect of IMN dissection and radiation on survival, and recent results of IMN lymphoscintigraphy and SLN biopsy. Incidence of internal mammary and axillary lymph node metastases Clinical review based on the results of reports of extended radical mastectomy confirms the importance of the IMN chain as a major pathway of lymphatic drainage. Among seven studies of extended radical mastectomy (ERM) (totaling 4,172 breast cancer patients), the estimated incidence of IMN metastasis at the time of surgery ranged from 18% to 33% (Table 1). Fourteen percent to 24% of all patients had both IMN and axillary node (AN) metastases, whereas only 2% to 11% of patients had IMN metastases alone (Table 1). Of the 2,107 AN-positive patients, 29% to 52% had IMN metastases (Table 2). Of the 2,065 AN-negative patients, 4% to 18% had IMN metastases (Table 2).