Multicentric primaries and residual tumor masses following wide excision in breast cancer: a basis for irradiation.

In the Department of Gynecology and Obstetrics 131 modified radical mastectomies were carried out in patients with invasive breast cancer eligible for breast conserving therapy between 1978 and 1981. The technique of plastination was used for the first time in a complete histological investigation of the breast specimens. In all cases segmental resections with a rim of crossly normal tissue around the primary of at least 2 cm were simulated. Residuals of the primary in vicinity of the resection margin were found in 19.1% and multicentric tumor foci in 24.4% of all cases in the remaining breast. In 8.4% of the patients the residuals extended more than 3 cm beyond the resection margin. The volumes of the residuals were significantly larger than the volumes of the multicentric foci (p = 0.004). According to these results a 2 cm rim of grossly normal tissue should be resected with the primary tumor. A reexcision is to be recommended in cases with resection margins that are histologically not free of tumors. Considering the difficulty of a total histologic examination of the whole resection margin a boost dose should be supplemented. The extension of the residuals requires a boost field covering one third up to one half of the normal sized breast.