Breast carcinomas of limited extent - Frequency, radiologic-pathologic characteristics, and surgical margin requirements

BACKGROUND, Clinical trials established the Value of breast-conserving trea tment (BCT) including the macroscopic removal of the tumor followed by loca l radiation therapy (RT) for Stage I and II invasive carcinomas. The occurr ence of local tumor recurrence is related to the extent and multifocality o f the tumor. Various studies aim to identify those tumors that could be pro per candidates for conventional BCT. Furthermore, recent studies have focus ed on the identification of tumors that may be treated by breast-conserving surgery alone without RT. Small, localized tumors theoretically should be the potential candidates for this type of treatment. The mammographic and p athologic criteria for the identification of tumors with limited extent are not yet established; furthermore, the optimal extent of the surgical excis ion and the method for margin examination are controversial. METHODS. Surgical breast-conserving procedures were simulated in a review o f 135 mastectomy specimens of patients treated for an invasive carcinoma (l ess than or equal to4 cm in size, all pathologic types except invasive lobu lar carcinoma) two were theoretically eligible for conservative treatment. Tumor spread including possible multifocality and multicentricity was studi ed by the technique of correlated specimen radiography and pathology. Breas t carcinoma of limited extent (BCLE), the proper tumor profile for BCT, tva s defined as having no invasive carcinoma, ductal carcinoma in situ, and ly mphatic emboli foci beyond 1 cm from the edge of the dominant mass. RESULTS. Fifty-three percent of the patients in this series had a BCLE. No statistically significant relation was found between BCLE and patient age, pathologic size, type and grade of the tumor, lymph node status, mode of de tection, and mammographic aspect of the index tumor. Based on mammography, the absence of calcification or tumor density beyond the edge of index tumo r appears to be the best predictor for BCLE (P < 0.0001). A 1-cm microscopi cally tumor free margin as the outer rim of a macroscopic surgical margin o f 2 cm gives the best positive predictive value based on pathology (P < 0.0 001). By applying the above conditions, 72 of the 135 cancers were identifi ed as being potential BCLE cases in this series. However, whereas 64 of the se 72 tumors (89%) were correctly identified as being true BCLE, 8 (11%) we re erroneously identified as such (non-BCLE cases), having "residual" tumor foci beyond 2 cm from the edge of the dominant tumor. CONCLUSIONS. We conclude, that approximately 50% of invasive ductal carcino mas may have limited extent. The accuracy of identifying this group of canc ers, the proper candidates for BCT, by applying state-of-the-art mammograph y and pathology may be as high as 90%. A subset of these tumors might repre sent the potential candidates for treatment with surgery alone without RT. As a result, the routine application of BCT complemented by RT would have l ed to the overtreatment of 89% of the patients with a BCLE in this series; conversely, 11% of the tumors may have recurred without the use of RT. Cons idering that these conclusions are based on a theoretic morphologic model, further clinical studies with facilities for high quality team approach in diagnosis and therapy are needed to evaluate the impact of BCLE on BCT stra tegies. The results of this study should not justify the withholding of RT outside the context of clinical trials. (C) 2001 American Cancer Society.