Abstract
PurposeIMPORT LOW demonstrated noninferiority of partial-breast and reduced-dose radiotherapy versus whole-breast radiotherapy for local relapse and similar or reduced toxicity at 5 years. Comprehensive patient-reported outcome measures collected at serial time points are now reported.Patients and MethodsIMPORT LOW recruited women with low-risk breast cancer after breast-conserving surgery. Patients were randomly assigned to 40 Gy whole-breast radiotherapy (control), 36 Gy whole-breast and 40 Gy partial-breast radiotherapy (reduced-dose), or 40 Gy partial-breast radiotherapy only (partial-breast) in 15 fractions. European Organisation for Research and Treatment of Cancer Quality of Life Questionnaires Core 30 and Breast Cancer–Specific Module, Body Image Scale, protocol-specific items, and the Hospital Anxiety and Depression Scale were administered at baseline, 6 months, and 1, 2, and 5 years. Patterns of moderate/marked adverse effects (AEs) were assessed using longitudinal regression models, and baseline predictors were investigated.ResultsA total of 41 of 71 centers participated in the patient-reported outcome measures substudy; 1,265 (95%) of 1,333 patients consented, and 557 (58%) of 962 reported no moderate/marked AEs at 5 years. Breast appearance change was most prevalent and persisted over time (approximately 20% at each time point). Prevalence of breast hardness, pain, oversensitivity, edema, and skin changes reduced over time (P < .001 for each), whereas breast shrinkage increased (P < .001). Analysis by treatment group showed average number of AEs per person was lower in partial-breast (incidence rate ratio, 0.77; 95% CI, 0.71 to 0.84; P < .001) and reduced-dose (incidence rate ratio, 0.83; 95% CI, 0.76 to 0.90; P < .001) versus whole-breast group and decreased over time in all groups. Younger age, larger breast size/surgical deficit, lymph node positivity, and higher levels of anxiety/depression were baseline predictors of subsequent AE reporting.ConclusionMost AEs reduced over time, with fewer AEs in the partial-breast and reduced-dose groups. Baseline predictors for AE reporting were identified. These findings will facilitate informed discussion and shared decision making for future patients receiving moderately hypofractionated breast radiotherapy.
Highlights
Trials of hypofractionated whole-breast radiotherapy after breast-conserving surgery have demonstrated that 40 Gy in 15 fractions is safe and effective, with patients reporting lower levels of moderate/marked adverse effects (AEs) compared with 50 Gy in 2-Gy daily fractions.[1,2] the 3-week regimen tested in the START-B (UK Standardisation of Breast Radiotherapy B) trial[1] has become standard of care in the UnitedKingdom for whole-breast radiotherapy and is used internationally.[3]
A total of 41 of 71 centers participated in the patient-reported outcome measures substudy; 1,265 (95%) of 1,333 patients consented, and 557 (58%) of 962 reported no moderate/marked AEs at 5 years
Analysis by treatment group showed average number of AEs per person was lower in partial-breast and reduced-dose versus whole-breast group and decreased over time in all groups
Summary
Trials of hypofractionated whole-breast radiotherapy after breast-conserving surgery have demonstrated that 40 Gy in 15 fractions is safe and effective, with patients reporting lower levels of moderate/marked adverse effects (AEs) compared with 50 Gy in 2-Gy daily fractions.[1,2] the 3-week regimen tested in the START-B (UK Standardisation of Breast Radiotherapy B) trial[1] has become standard of care in the UnitedKingdom for whole-breast radiotherapy and is used internationally.[3]. LOW (Intensity-Modulated and Partial-Organ Radiotherapy Low Risk) investigated efficacy of partial-breast versus whole-breast irradiation using standard UK hypofractionated radiotherapy.[4] The randomized trial schedules were: 40 Gy whole-breast radiotherapy (control); 36 Gy whole-breast and 40 Gy partial-breast radiotherapy (reduced-dose group); and 40 Gy partial-breast radiotherapy only (partial-breast group) in 15 daily fractions, using simple intensity-modulated radiotherapy (IMRT; Fig 1). IMPORT LOW demonstrated noninferiority of partial-breast and reduced-dose radiotherapy compared with standard wholebreast radiotherapy for local relapse, with similar or fewer late normal-tissue AEs at 5 years using clinician assessments, patientreported outcome measures (PROM), and serial photographs.[4] These published results demonstrated that at 5 years, patients generally reported fewer moderate/marked AEs for skin changes, breast appearance change, smaller breast, and harder/firmer breast to touch in the partial-breast group compared with the wholebreast group, the reduction was only statistically significant (P , .001) for change in breast appearance.[4]
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