Multivariate Preoperative and Intraoperative Predictors of Postmastectomy Radiation Therapy in Patients for Whom Immediate Breast Reconstruction Is Planned

Background: Postmastectomy radiation therapy often impacts decision-making and outcomes of breast reconstruction. However, plastic surgeons typically have limited information regarding the likelihood of radiation therapy when decisions about immediate breast reconstruction are made. The study objective was to examine whether commonly available information can be used to predict the probability of radiation therapy. Methods: A retrospective review was performed of patients undergoing mastectomy and sentinel lymph node biopsy. Multivariate logistic regression analysis of variables available in greater than 95 percent of patients was performed in relation to predicting radiation therapy. Results: A total of 322 patients were reviewed, of whom 55 (17.1 percent) received radiation therapy, which was indicated for patients having four or more positive axillary lymph nodes in all cases. Multivariate logistic regression identified the intraoperative sentinel lymph node frozen section results (OR, 27.3), tumor size (OR, 1.7), and age (OR, 0.96) as significant predictors. The sentinel lymph node frozen section exhibited negative and positive predictive values for radiation therapy of 95.4 percent and 54.3 percent, respectively. When sentinel lymph node frozen section was combined with tumor size greater than or equal to 2.0 cm, the positive predictive value increased to 80.5 percent. Conclusion: Immediate breast reconstruction patients who have negative intraoperative sentinel lymph node frozen section results have a less than 5 percent chance of radiation therapy, whereas patients with positive intraoperative sentinel lymph node frozen section results and tumor size greater than or equal to 2.0 cm have a greater than 80 percent chance of radiation therapy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

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