BREAST PRESERVATION IN STAGE-I AND STAGE-II CARCINOMA OF THE BREAST -THE UNIVERSITY-OF-CHICAGO EXPERIENCE

BACKGROUND. Although breast conservation has received increased accept ance, there are still unresolved issues regarding local treatment tech niques, such as the extent of surgery, in relation to the final margin s of excision and the use of tumor bed boost radiation. The goal of th is study was to determine the local control and breast preservation wi th particular emphasis on the importance of the final microscopic marg ins in patients receiving tumor bed boost therapy. METHODS. The author s analyzed 869 cases of Stage I and II breast carcinoma in 852 women w ho were treated with breast-conserving surgery and radiation therapy b etween 1984 and 1994. The median follow-up was 43 months. Final micros copic margins were negative in 762 (88%), microscopically positive in 82 (9%), and unknown in 25 (3%) of the patients. Negative margins were defined as no tumor cells at the surgical margin. The patients were t reated with external beam radiation therapy to the entire breast to a median dose of 46 Gray (Gy). A boost to the tumor bed was delivered to 863 (99%) of the patients. The median tumor bed dose was 60 Gy. A mul tivariate analysis of factors impacting on the local control and overa ll survival was performed. Variables introduced into the model include d size, age, lymph node status, microscopic margins, nuclear grade, hi stologic grade, and estrogen and progesterone receptor status. RESULTS . The actuarial 5-year local control rate was 97%. The median time to local failure was 32 months (range, 14-69 months). In multivariate ana lysis, the only significant factor affecting local control was the sta tus of margins. In patients receiving boost radiation to the excision site, the local control rate at 5 years was 98% and 89%, respectively, if the margins were negative or positive (P < 0.01). This resulted in 5-year actuarial breast preservation rates of 98% and 92% (P = 0.03). In the patients in whom the margins of excision were microscopically positive, the local control rate was 91% if the total dose to the tumo r bed was >60 Gy compared with 76% for a dose less than or equal to 60 Gy (P = 0.05). The 5-year actuarial overall survival rate was 89%. Ap proximately 94% of the women considered their cosmetic outcome good to excellent.CONCLUSIONS. By obtaining microscopically negative margins and using tumor bed boost therapy, excellent local control, breast pre servation, and cosmesis can be achieved. In patients with microscopica lly positive margins, an acceptable local control rate can be achieved if a tumor bed boost is given. (C) 1996 American Cancer Society.