Factors related to re-excision procedures following primary breast-conserving surgery for women with breast cancer in the U.S. Military Health System

Background and Objectives: Re-excision surgery is undertaken to obtain clear margins after breast-conserving surgery (BCS) for localized breast cancer. This study examines patient and tumor characteristics related to re-excision surgery in the universal-access Military Health System (MHS). Methods: Retrospective analysis of patients with pathologically confirmed stage I-III breast cancer between 1998 and 2014 in the Department of Defense Central Cancer Registry and MHS Data Repository–linked databases who received primary BCS. Multivariable stepwise logistic regression methods identified characteristics associated with re-excision surgery (lumpectomy and mastectomy) and conversion to mastectomy, given as adjusted odds ratios (AOR) and 95% confidence intervals (CIs). Results: Of 7637 women receiving BCS, 26.3% had a re-excision and 9.9% converted to mastectomy. Tumor location, larger tumor size (≥4 cm), and regional lymph node involvement were associated with a greater likelihood of re-excision and mastectomy conversion. Pathology before BCS (AOR, 0.39; 95% CI, 0.35, 0.44 for re-excision) and neoadjuvant treatment (AOR, 0.50; 95% CI, 0.36, 0.69 for re-excision) were associated with a decreased likelihood of these outcomes. Additionally, age, tumor histology, and military-specific variables were associated with mastectomy conversion. Conclusion: Comprehensive preoperative workup, including tumor pathology, may better inform surgical decision-making and reduce re-excision rates.