INFLUENCE OF PATIENT CHARACTERISTICS, SOCIOECONOMIC-FACTORS, GEOGRAPHY, AND SYSTEMIC RISK ON THE USE OF BREAST-SPARING TREATMENT IN WOMEN ENROLLED IN ADJUVANT BREAST-CANCER STUDIES - AN ANALYSIS OF 2 INTERGROUP TRIALS

Purpose: To investigate the frequency of breast-sparing treatment amon g breast cancer patients subsequently enrolled in notional cooperative group studies of adjuvant chemotherapy. Patients and Methods: A data base was formed of 5,172 patients randomized onto two intergroup trial s. Lumpectomy rates were analyzed within study-defined risk strata and across geographic regions. Significant predictors of lower lumpectomy usage were determined in multivariate analyses-with variables that de scribed patient and disease characteristics, systemic risk strata, geo graphic region, and socioeconomic indicators based on zipcode of resid ence. Results: Breast-conservation rates were 30% in the node-negative and 15% in the node-positive trials, with a wide geographic variation within each study (range, 14% to 49% and 9% to 31%, respectively). Lu mpectomy use declined with increasing tumor size and did not exceed 40 % even for tumors less than or equal to 1 cm with negative nodes. With increasing risk of systemic relapse, frequency of lumpectomy declined (rates for five strata in order of increasing systemic risk: 41%, 33% , 24%, 18%, and 11%), even though these strata were not known at the t ime of the surgical decision. A logistic model confirmed the joint sig nificance of geographic region and systemic risk. An exploratory model that adjusted for all important variables identified the following si gnificant predictors of lower lumpectomy use: positive nodes; many pos itive nodes, increased systemic risk; tumor sire greater than or equal to 2.0 cm; older age; South, Central or non-New England regions; and either lack of college degree or lower income levels. Conclusion: Brea st-sparing therapy was used in the minority of women subsequently accr ued to two national adjuvant breast cancer studies, even though this c ohort and their referring surgeons represented a select population. Al though multiple concrete factors were independent predictors of lower lumpectomy rates, prospective research is needed into how patients and their physicians approach the mastectomy versus lumpectomy decision. (C) 1996 by American Society of Clinical Oncology.