Irradiation of the tumor bed alone after lumpectomy in selected patients with early-stage breast cancer treated with breast conserving therapy

Backgrounds and Objectives: We present the interim findings of our in-house protocol treating the tumor bed alone after lumpectomy with low-dose-rate (LDR) interstitial brachytherapy in selected patients with early-stage brea st cancer treated with breast conserving therapy (BCT). Methods: From 1 March 1993 through 1 January 1995, 50 women with early-stag e breast cancer were entered into a protocol of tumor bed irradiation alone using an interstitial LDR implant. Patients were eligible if their tumor w as an infiltrating ductal carcinoma less than or equal to 3 cm in diameter, surgical margins were clear by at least 2 mm, the tumor did not contain an extensive intraductal component, the axilla was surgically staged with les s than or equal to 3 nodes involved with cancer, and a postoperative mammog ram was performed. Implants were positioned using a template guide deliveri ng 50 Gy over 96 hr to the lumpectomy bed plus a 1-2-cm margin. Local contr ol, cosmetic outcome, and complications were assessed. Results: Patients ranged in age from 40 to 84 pears (median, 65). The media n tumor size was 10 mm (range. 1-25). Seventeen of 50 patients (34%) had we ll-differentiated tumors, 22 (44%) had moderately differentiated tumors, an d in 11 (22%) the tumor was poorly differentiated. Forty-five patients (90% ) were node-negative while five (10%) had 1-3 positive nodes. A total of 23 (46%) patients were placed on tamoxifen and 3 (6%) received adjuvant syste mic chemotherapy. No patient was lost to followup. The median follow-up for surviving patients is 47 months (range, 37-59). No patient has experienced a local, regional, or distant failure. Three patients have died at 19, 33, and 39 months after treatment. All were without clinical evidence of recur rent disease and all deaths were unrelated to treatment. Good-to-excellent cosmetic results have been observed in 49 of 50 patients (98%) (median cosm etic follow-up was 44 months with a range of 19-59). No patient has experie nced significant sequelae related to their implant. Conclusions: Interim results with treatment of the tumor bed alone with an LDR interstitial implant appear promising. Long-term follow-up of these pat ients and additional studies will be necessary to establish the equivalence of this treatment approach compared to standard BCT. J. Surg. Oncol. 1999; 70:33-40. (C) 1999 Wiley-Liss, Inc.