Association of Therapeutic Mammoplasty and Radiotherapy Side-effects

Introduction Patients with larger breast size and volume are at increased risk of clinically significant side-effects (toxicity) from radiotherapy. Therapeutic mammoplasty (TM) extends the role of breast-conserving surgery (BCS) by combining wide local excision of the cancer with breast reduction and mastopexy techniques. The aim of this study was to determine the effect of TM using level 2 oncoplastic techniques on the incidence of early and long-term radiotherapy side-effects. Patients and Methods Breast cancer patients recruited prospectively into the multicentre REQUITE cohort study (www.requite.eu) at a single institution (n=346) were included. Radiotherapy side-effects (CTCAE v4.0) were scored at baseline, following radiotherapy, and at 2-year follow-up. The association of TM and specimen resection weight were investigated in multivariable regression models adjusted for patient and treatment co-variates. Results At 2 years, 20.1 % of patients had grade ≥2 atrophy, 23.2% grade ≥1 tumour bed induration (fibrosis), 12.6% grade ≥1 breast induration, and 12.1% grade ≥1 telangiectasia. 22.5 % of patients (n=78) underwent TM. TM patients had larger tumours (p=0.006) and specimen resection weights (p<0.001). TM but not specimen resection weight was associated with reduced tumour bed induration (Odds ratio=0.12, 95% CI 0.035 - 0.395, p=0.001), breast induration (OR 0.19, 95% CI 0.043 - 0.852, p=0.03) and telangiectasia (OR 0.12, 95% CI 0.020 - 0.736, p=0.02). Neither TM nor specimen weight had any effect on atrophy or early radiotherapy side-effects. Conclusion TM but not resected specimen weight was associated with fewer long-term side-effects from breast radiotherapy. This implies that the incidence of side-effects is affected not by reducing the overall radiotherapy target volume but by re-shaping the breast, which is likely to reduce dose inhomogeneity. MicroAbstract Therapeutic mammoplasty was associated with significantly lower rates of long-term breast induration and telangiectasia following whole-breast radiotherapy, independent of resection weight and other patient and treatment factors. These findings suggest that breast reshaping, rather than tissue volume reduction alone, may reduce clinically significant late radiotherapy toxicity.