Internal mammary lymphoscintigraphy in the conservative management of breast carcinoma: an update and recommendations for a new TNM staging.

The results of internal mammary lymphoscintigraphy (IML) in 524 patients with breast carcinoma who underwent partial mastectomy, with or without axillary dissection, demonstrate the predictive value of an abnormal lymphoscintigram. There was a significant difference (P less than 0.0005) in actuarial survival between patients with normal and abnormal IML. In view of the increased mortality associated with metastases to both internal mammary and axillary lymphatics compared with involvement of either site alone, and the most favourable outcome in patients with involvement of neither site, it is proposed that the current TNM staging for breast carcinoma should henceforth include the status of internal mammary lymph nodes determined by radiocolloid lymphoscintigraphy. Further refinement of the N status into NA (axilla) and N1 (internal mammary nodes) is suggested. Stages I, II, and III should designate, respectively, patients with no evidence of involvement of either lymphatic site, patients with involvement of one or the other site and patients with involvement of both sites. This would constitute a more rational approach to the staging and management of the patient with breast carcinoma and would also provide a more accurate means of evaluating the true efficacy of current strategies in comparable groups of patients. Unrecognised internal mammary lymphatic metastases have probably confounded the results of past prospective trials.