Results of biopsies performed after breast conservation therapy for stage I-II breast cancer

Abstract

843 Background: This study was performed to identify the factors predictive of positive biopsy after breast conservation therapy with definitive breast irradiation (RT) for early stage breast cancer. Methods: The records of patients treated for stage I-II unilateral or bilateral invasive breast cancer between 1977 and 1996 were reviewed to identify patients who had undergone post-treatment ipsilateral breast biopsies. Results: There were 195 biopsies performed in 193 treated breasts. The median time to biopsy was 49 months (mos) after irradiation. Among all biopsies, 59% were positive and 41% were negative. Subsequent biopsies were performed in 28 breasts, of which 27% were positive, thus 12% of women with a negative first biopsy later developed local recurrence. Biopsies were positive in 41% of patients with physical exam (PE) findings only, in 69% with mammographic findings only and in 80% with physical exam and mammographic abnormalities (p=0.001). When analyzed by type of biopsy, core biopsies were positive in 85% (6 of 7), excisional biopsies in 58%, and fine needle aspirations were positive in 28% (p=0.025). When analayzed by age at diagnosis, positive biopsies were obtained in 54% of patients age 51 or older, in 59% of patients age 36 to 50 and in 83% of patients 35 years or younger (p=0.05). Positive biopsy rate also increased with the interval from completion of radiation, as follows: ≤ 60 months = 50%; 61–120 months = 67%; 121–180 months = 80%; ≥ 181 months = 100% positive biopsies (p=0.01). Positive biopsy rate was not correlated with location of recurrence, pathologic T or N stage, ER/PR status or final pathologic margins of excision (all p ≥ 0.15). Conclusions: Biopsy remains the standard for diagnosis of local recurrence after breast conservation therapy. In this study, we identified groups at high risk for a positive biopsy. No significant financial relationships to disclose.