Predicting factors for no residual disease in breast cancer re-excision post breast conserving surgery: A ten-year cohort.

Abstract

Introduction Appropriate margin width in breast conserving surgery for breast cancer remains debatable, and of those patients who undergo re-excision for positive margins, only half are found to have residual cancer. This study aimed to identify predicting factors for no residual disease upon re-excision in order to determine the patient group in which re-excision could be safely waived. Materials and Methods We conducted a retrospective cohort study of patients who had undergone re-excision post breast conserving surgery at the Breast Centre of the Unidade Local de Saúde de São João between July 2014 and June 2024. Predicting factors were sought using chi-square statistics and both univariate and multivariate logistic regression models to compute odds ratio (OR) and corresponding 95% confidence intervals (CI). Results Of the 159 patients included in this study, 77 (48.4%) showed no signs of residual disease on re-excision specimen. Cancer in proximity to margins rather than intercepted (OR=4.42, 95%CI: 2.03-9.63) and invasive histology with no DCIS component (OR =3.20, 95%CI: 1.01-10.19) were associated with no residual disease upon re-excision. Contrarily, neoadjuvant endocrine therapy (NET) (OR=0.36, 95%CI: 0.14-0.94) and specimen radiography on first surgery (OR=0.32, 95%CI: 0.12-0.86) were found to positively associated to residual disease. Discussion Patients in which tumour is close to but does not intercept margins are over fourfold more likely to undergo an unnecessary re-excision. We propose that in such cases a second operative procedure might be waived, especially if the patient will be undergoing adjuvant radiotherapy, and excepted for those submitted to NET.