Temporal impact of the publication of guidelines and randomised evidence on the adoption of hypofractionated whole breast radiotherapy for early-stage breast cancer

Introduction: Clinical data supporting the use of hypofractionated whole breast radiotherapy (HF-WBRT) in early-stage breast cancer patients have accumulated over the last decade. Despite the availability of the published evidence, the adoption rate of HF-WBRT has been slower-than-expected. We sought to assess the temporal impact of the publication of the guidelines and randomised evidence on the practice pattern of HF-WBRT and identify clinical predictors of its utilisation. Methods: Women with early-stage breast cancer who received adjuvant WBRT at Canberra Health Services between 2008 and 2016 were identified from clinical databases. The patterns of HF-WBRT use were analysed in relation to pre-specified time periods (before and after the guideline publications) in the entire cohort as well as in a patient subset fulfilling the criteria for HF-WBRT according to the guidelines (referred to as ‘guideline-endorsed subset’). The impact of clinical variables, treating clinicians and the time periods on the adoption of HF-WBRT was assessed by hierarchical multivariate logistic regressions. Results: Of the entire cohort (n = 1171), the guideline-endorsed subset constituted 51.6% (n = 604) of the patients. HF-WBRT was utilised in 32.8% of the entire cohort and 46.2% of the guideline-endorsed subset. Between 2008 and 2016, HF-WBRT use rate increased from 12.1% to 56.6% in a non-linear pattern. Release of international and local consensus guidelines significantly correlated with the increase in HF-WBRT utilisation rate. The use of chemotherapy and/or tumour bed boost radiotherapy (TBBR), chest wall sepJMIROtion distance (CWSD) and patient age were significant predictors of HF-WBRT use on multivariate analyses. After factoring in the effects of individual clinicians and the time periods on hierarchical multivariate analyses, the use of chemotherapy, TBBR, and CWSD remained as significant variables. Clinicians contributed to the variability in the HF-WBRT adoption pattern. Conclusion: The temporal uptake pattern and the predictors of adjuvant HF-WBRT use in early breast cancer patients largely reflected the accumulating clinical evidence and the publication of the consensus guidelines. This study identified potentially modifiable factors associated with slower-than-expected uptake rate of HF-WBRT. Understanding why there is variability in clinicians’ readiness to adopt the abbreviated treatment despite the availability of advanced radiotherapy techniques and the updated evidence is an important step towards formulating effective strategies to optimise the radiotherapeutic management of this common malignancy.