Predictors of Adverse Cosmetic Outcome in the RAPID Trial: An Exploratory Analysis
Menée sur 1 108 patientes atteintes d'un cancer du sein et ayant reçu une radiothérapie du sein entier ou une irradiation partielle accélérée par radiothérapie conformationnelle 3D, cette étude identifie les facteurs prédictifs associés à des résultats esthétiques indésirables 3 ans après traitement
Purpose : To evaluate factors associated with adverse cosmesis outcome in breast cancer patients randomized to accelerated partial breast irradiation (APBI) using 3D-conformal radiation therapy (3D-CRT) or whole breast irradiation (WBI) in the RAPID trial.
Methods and Materials : Subjects were trial participants with nurse assessed global cosmetic scores at baseline and at 3 years. Adverse cosmesis was defined as a score of fair or poor. Cosmetic deterioration was defined as any adverse change in score from baseline to 3 years. The analysis is based on data from the previously reported interim analysis. Logistic regression models were used to assess the association of risk factors for these outcomes among all patients and those treated with APBI only.
Results : Clinicopathologic characteristics were similar between subjects randomized to APBI (n=569) or WBI (n=539). For all subjects, factors associated with adverse cosmesis at 3 years were older age, central/inner tumor location, breast infection, smoking, seroma volume, breast volume and use of APBI; factors associated with cosmetic deterioration were smoking, seroma volume, and use of APBI (p<0.05). For APBI subjects, tumor location, smoking, age and seroma volume were associated with adverse cosmesis (p<0.05) and smoking was associated with cosmetic deterioration (p=0.02). An independent association between the V95/whole breast volume (WBV) ratio and adverse cosmesis (p=0.28) or cosmetic deterioration (p=0.07) was not detected. On further exploration a V95/WBV ratio <0.15 was associated with a lower risk of cosmetic deterioration (p=0.04), but this accounted for only 11% of patients.
Conclusion : In the RAPID trial, a number of patient tumor and treatment-related factors including the use of APBI were associated with adverse cosmesis and cosmetic deterioration. For patients treated with APBI alone, the high dose treatment volume was not independently associated with an adverse cosmetic outcome and a useful clinical threshold could not be identified.
International Journal of Radiation Oncology • Biology • Physics , résumé, 2014