[A role of interpectoral (Rotter's) lymph node dissection in modified radical mastectomy for breast cancer].

To study the influence of interpectoral lymph node (IPN) dissection on the prognosis of patients who underwent modified radical mastectomy, IPN was carefully dissected and studied pathologically on 168 cases of our breast cancer patients operated with modified radical mastectomy. There were 1.2 lymph nodes on an average in the interpectoral region, and they were almost 1-2mm in diameter. IPN metastases were found in 10 cases. (Tis: 0%, Stage I: 4.9%, Stage II: 5.7%, Stage III: 13%). Tumors located in outer quadrant in almost all these cases. Positive IPN were found in 6 (16%) of n1 alpha group, 1 (10%) of n1 beta group, and in 3 (50%) of n2 group. All these 3 cases of n2 died of distant metastasis and local recurrence. Two (1.7%) of axillary node (1a, 1b) negative patients had microinvolvement of cancer only in IPN, and are currently disease-free. These data suggest that IPN metastasis may occur even in the early breast cancer patients, and that may be controllable by lymph node excision. Therefore, routine and careful dissection of IPN through wide opening of sulcus interpectoralis is necessary for modified radical mastectomy and even for breast preserving operation.