California Northstate University College of Medicine Elk Grove, CA
A. H. Okabe1, W. L. Ho2, M. L. Tao3, and J. C. Ye3; 1California Northstate University College of Medicine, Sacramento, CA, 2Morsani College of Medicine, University of South Florida, Tampa, FL, 3Department of Radiation Oncology, University of Southern California Keck School of Medicine, Los Angeles, CA
Purpose/Objective(s): This single institution retrospective study compares the cosmetic outcomes of early-stage breast cancer patients treated with external beam moderately hypofractionated whole breast irradiation (WBI) or accelerated partial breast irradiation (PBI) following lumpectomy and aims to identify factors that predict outcomes.Materials/
Methods: 156 female patients (112 WBI, 44 PBI) treated from 2013 to 2023 were included. Demographic, clinical, surgical, toxicity, and cosmetic data were collected. Cosmesis was measured on the 4-point Harvard scale by the treating physician at the time of consultation and follow-up. Descriptive statistics was used to report the distribution of ratings. Fisher’s exact and Mann-Whitney U tests were used to compare cosmetic ratings between the two treatment groups and for univariate analysis to examine association with other clinical factors. Results: The median age at diagnosis was 56 years (range: 35-88) for the WBI cohort and 67 years (range: 52-85) for the PBI cohort (p<0.01). The median follow-up was 20.5 months for WBI and 26.0 months for PBI. Cosmetic scores for WBI were 10.1% Fair, 28.3% Good, and 61.6% Excellent, while those for PBI were 10.3% Fair, 20.5% Good, and 69.2% Excellent. The proportion of patients who were noted to have a decrease in cosmetic score was 10.9% in WBI and 10.7% in PBI. Patients who received WBI were significantly more likely to develop grade 2 or 3 radiation dermatitis, than PBI (p<0.01). However, there were no significant differences between the cosmetic outcomes of the WBI and PBI groups at each time point (baseline, 6 months, 1 year, 2 years, >3 years after completion of radiotherapy). No significant association was found between the final reported cosmesis and patient demographics, BMI, chemotherapy status, hormonal therapy status, surgical toxicities, or radiation position (supine or prone) for both WBI and PBI groups. However, radiation toxicities such as the development of lymphedema (p=0.03) and radiation pneumonitis (p=0.02) following treatment were significantly associated with an adverse cosmetic outcome in the WBI group. There was a significant association between the physician-scored baseline cosmesis and the cosmesis at the final follow-up for both WBI and PBI (p<0.001, p=0.021). Conclusion: There were no significant differences between the cosmetic outcomes for patients who received WBI compared to PBI. Cosmesis also did not depend on common patient and treatment related factors in this study. Those who received WBI were more likely to develop grade 2 or 3 radiation dermatitis. Cosmesis did not change from baseline in the vast majority of patients after either WBI or PBI, making surgical outcome the greatest predictor of long-term cosmetic outcome. PBI represents an alternative to WBI with decreased toxicity and comparable cosmetic outcome in appropriate patients with early-stage breast cancer.
