Risk factors for seroma evacuation in breast cancer patients treated with intraoperative radiotherapy.

Abstract Background Novel techniques in oncology provide new treatment opportunities but also introduce different patterns of side effects. Intraoperative radiotherapy (IORT) allows a shortened overall treatment time for early breast cancer either combined with whole breast radiotherapy (WBRT), or alone. Although the early side effects of IORT are well known, data on clinically important late side effects, which require medical intervention, are scarce. Aim In this study, we analyze risk factors for seroma evacuation more than 6 months after IORT. Materials and methods We evaluated 120 patients with a mean follow-up of 27.8 months (range: 7–52 months). Fifty-one patients received IORT only and 69 were additionally treated with WBRT. Results Seroma evacuation was performed 6–38 months after IORT. Two (3.9%) events were observed in the IORT group and 14 (20%) in the IORT + WBRT group. Univariate (Kaplan–Meier) analysis showed that addition of WBRT to IORT increased the risk of seroma evacuation [hazard ratio = 5.5, 95% confidence interval: 2.0–14.7, P  = 0.011]. In a multivariate analysis (Cox proportional hazards regression), WBRT and axillary lymph node dissection were significant risk factors for seroma evacuation (model P value = 0.0025). Conclusions WBRT applied after IORT is associated with increased risk of seroma evacuation, which might be considered as a late side effect.