A randomised controlled trial of post-operative radiotherapy following breast-conserving surgery in a minimum-risk population. Quality of life at 5 years in the PRIME trial.

OBJECTIVES To assess whether omission of post-operative radiotherapy (RT) in women with 'low-risk' axillary node-negative breast cancer [tumour size of less than 5 cm (T0-2) although the eligibility criteria further reduce the eligible size to a maximum of 3 cm] treated by breast-conserving surgery and endocrine therapy improves quality of life and is more cost-effective. DESIGN A randomised controlled clinical trial, using a method of minimisation balanced by centre, grade of cancer, age, lymphovascular invasion and preoperative endocrine therapy was performed. SETTING Breast cancer clinics in cancer centres in the UK. PARTICIPANTS Patients aged ≥ 65 years were eligible provided that their breast cancers were considered to be at low risk of local recurrence, they were suitable for breast conservation surgery, they were receiving endocrine therapy and they were willing and able to give informed consent. INTERVENTIONS The standard treatment of post-operative whole breast irradiation or the omission of RT. MAIN OUTCOME MEASURES Quality of life was the primary outcome measure, together with anxiety and depression and cost-effectiveness. Secondary outcome measures were recurrence rates and survival, and treatment-related morbidity. The principal method of data collection was by questionnaire, completed at home with a research nurse on four occasions over 15 months, then by postal questionnaire at 3 and 5 years after surgery. RESULTS The hypothesised improvement in overall quality of life with the omission of RT was not seen in the summary domains of the European Organisation for Research in the Treatment of Cancer (EORTC) scales. Some differences were apparent within subscales of the EORTC questionnaires, and insights into the impact of treatment were also provided by the qualitative data obtained by open-ended questions added by the trial team. Differences were most apparent shortly after the time of completion of RT. RT was then associated with increased breast symptoms and with greater (self-reported) fatigue, but with lower levels of insomnia and endocrine side effects. These statistically significant differences in breast symptoms persisted for up to 5 years after RT [mean difference, RT was 5.27 units greater than no RT, 95% confidence interval (CI) of 1.46 to 9.07], with similar, though non-significant, trends in insomnia. No significant difference was found in the overall quality of life measure, with the no RT group having 0.36 units greater quality of life than the RT group (95% CI -5.09 to 5.81). CONCLUSIONS Breast RT is tolerated well by most older breast cancer patients without impairing their overall health-related quality of life (HRQoL). Although HRQoL should always be taken into account when determining treatment, our results show that the addition of RT does not impair overall quality of life. Further economic modelling on the longer-term costs and consequences of omitting RT is required. TRIAL REGISTRATION Current Controlled Trials ISRCTN14817328. FUNDING This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol 15, No. 12. See the HTA programme website for further project information.