Background: Controversy exists regarding internal mammary lymph nodes (IMNs) in the staging and treatment of breast cancer. Sentinel lymph node identification with radiocolloid can map drainage to IMNs and directed biopsy can be performed with minimal morbidity. Furthermore, recent studies suggest that IMN drainage of breast tumors may be underestimated. To gain further insight into the prognostic value of IMNs, we reviewed the outcome of patients in whom the IMN status was routinely assessed.
Methods: A retrospective review of 286 patients with breast cancer who underwent IMN dissection between 1956 and 1987 was conducted.
Results: Median follow-up is 186 months, age was 52 years (range, 21-85 years), tumor size was 2.5 cm, and number of IMNs removed was 5 (range, 1-22); 44% received chemotherapy, 16% endocrine therapy, and 5% radiotherapy. Presence of IMN metastases correlated with primary tumor size (P < .0001) and number of positive axillary nodes (P < .0001) but did not correlate with primary tumor location or age. Overall, the 20-year disease-free survival is significantly worse for the 25% of patients with IMN metastases (P < .0001). In patients with positive axillary nodes and tumors smaller than 2 cm, there was a significantly worse survival (P < .0001) in the patients with IMN metastases. This difference in survival was not seen in women with tumors larger than 2 cm.
Conclusions: Patients with IMN metastases, regardless of axillary node status, have a highly significant decrease in 20-year disease-free survival. Treatment strategies based on knowledge of sentinel IMN status may lead to improvement in survival, especially for patients with small tumors. At present, sentinel IMN biopsies should be performed in a clinical trial setting.