Intraductal carcinoma of the breast.

The management of intraductal carcinoma of the breast at the present time is necessarily diverse because there is difficulty in detecting it, as well as understanding its basic biology and natural history. Therapy has ranged from excisional biopsy with or without radiation to radical and extended radical mastectomy. The effects of radiation therapy upon these well-differentiated in situ lesions is undefined. The popularity of total mastectomy stems from a concern for the fate of breast tissue left in situ after removal of the focus of preinvasive carcinoma. Intraductal carcinoma of the breast has been shown to be a multicentric disease process in a large percentage of patients. Indeed, all breast tissue in these patients appears to be at risk for the eventual development of preinvasive and invasive carcinoma. However, the clinical significance of such residual foci of in situ carcinoma or ductal hyperplasia and dysplasia following resection of the breast, as in papillary carcinoma of the thyroid, is still open to question. Similar concern exists for a significant "sampling error" involved in biopsies of lesions of the breast: there were six instances of this in the present series (11 per cent). A "sampling error" of 6 per cent was found in a similar study of a group of patients with intraductal carcinoma. An error rate of 18 per cent was reported in another study. Again, the clinical significance of this "sampling error" remains open to question. The difficulty encountered in evaluating remaining breast tissue after a partial mastectomy has also been reason to consider total mastectomy in these patients. Residual or recurrent carcinoma in such altered breast tissue is difficult to diagnose at an early stage, either by physical examination or by the results of mammography. None of the patients in the present series had axillary nodal metastases and, theoretically, intraductal carcinoma should not be associated with axillary nodal metastasis. The small percentage of patients found to have invasive carcinoma following mastectomy for in situ carcinoma are likely to have minimally invasive lesions with, at most, a 23 per cent incidence of positive axillary nodes. The advantage gained by performing full axillary dissection or extensive nodal sampling in 60 per cent of the patients in this series, as well as in patients in other series, is difficult to ascertain without further study. The most logical choice of therapy would appear to be total mastectomy with limited axillary node sampling.(ABSTRACT TRUNCATED AT 400 WORDS)