Abstract P4-10-01: Twenty-Five Year Results in the Treatment of Early Breast Carcinoma with Mastectomy Versus Breast Conservation Therapy: The National Cancer Institute Randomized Trial

Abstract

Abstract Background: Breast conservation therapy (BCT) has become an accepted treatment in women with early stage breast cancer due to multiple randomized trials showing equivalent mortality rates when compared to modified radical mastectomy (MRM). Results of the National Cancer Institute's prospective randomized trial comparing MRM to BCT are now reported at a median follow up of 25.4 years. Methods: Between 1979 and 1987, 237 evaluable patients with biopsy proven clinical Stage I or Stage II primary breast cancer were randomized to receive a MRM or a lumpectomy followed by definitive radiation to the entire breast followed by a boost to the tumor bed. An axillary dissection was performed in both arms. Negative margins were not required. Patients with node positive disease in either arm were treated with adriamycin and cytoxan. The primary endpoints were overall survival and disease-free survival. Results: At a median follow-up of 25.4 years, there was no statistical difference in overall survival between either arm, with 45.7% of patients alive in the MRM group and 38.0% alive in the BCT group (p=0.43). Although disease-free survival was significantly worse in patients randomized to BCT (57% vs 82%, P<0.001), the additional treatment failures in the BCT group were primarily isolated ipsilateral breast tumor recurrences (IBTR's) which were salvaged by MRM. 22.3% of BCT patients experienced an IBTR but those patients had no significant decrease in overall survival. There were no differences in distant metastasis between the groups. Clinical factors associated with a worse prognosis include the presence of nodal disease (HR 2.46, 95% CI 1.71-2.71, P<0.05) and tumor size (HR 1.91, 95% CI 1.346-2.711, P<0.05). Conclusion: The 25 year survival rate among women receiving BCT vs MRM in the National Cancer Institute randomized trial appears to be equivalent and is consistent with findings across multiple trials. In patients receiving BCT there is an increased incidence of IBTR's. Despite a higher risk of local failure in the BCT group, there is no increased risk of distant failure or mortality. The risk of local failure however, should be discussed when counseling patients regarding their treatment options. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-10-01.