Impact of Regional Nodal Irradiation and Hypofractionated Whole-Breast Radiation on Long-Term Breast Retraction and Poor Cosmetic Outcome in Breast Cancer Survivors

Purpose: We performed a prospective longitudinal study to determine predictors of long-term breast asymmetry in breast cancer patients treated with breast-conserving surgery and whole-breast external-beam radiotherapy (XRT).

Patients and methods: A total of 109 patients with stage 0 to III breast cancer treated with breast-conserving surgery followed by conventional (50 Gy plus boost) or hypofractionated (39.9 Gy with simultaneous integrated boost of 48 Gy) XRT were enrolled onto 2 studies of XRT-induced skin toxicity before (baseline), during, and 1 year after XRT. Using baseline and 1-year post-XRT photographs, breast asymmetry was objectively quantified by calculating the percentage breast retraction assessment (pBRA), with larger values indicating more asymmetry. Skin thickness ratio (STRA) values were calculated using ultrasound images. Univariate and multivariate analyses were conducted to determine the relationship among STRA-, patient-, tumor-, and treatment-related factors, and pBRA.

Results: Seventy-one patients (65%) had more breast asymmetry (positive change in pBRA) 1 year after XRT relative to baseline. Only pre-XRT STRA was associated with a higher pre-XRT baseline pBRA in multivariate analysis (P = .02). Larger breast volume, baseline pBRA, conventionally fractionated (vs. hypofractionated) XRT, supraclavicular nodal irradiation, and higher STRA at 1 year predicted for higher long-term pBRA in the multivariate model (all P < .05). Breast volume and supraclavicular nodal irradiation were associated with the largest changes in breast asymmetry (all P < .05).

Conclusion: This prospective longitudinal study confirmed the known impact of breast volume, surgery, and XRT on breast asymmetry. We also found that supraclavicular nodal irradiation and conventionally fractionated XRT are associated with worse cosmetic outcome 1 year after XRT.