An Analysis of the Utilization of Hypofractionated Regimens for Early Stage Breast Cancer at a Tertiary Care Cancer Center and Its Community-Based Affiliates

Abstract

Multiple clinical trials have demonstrated that hypofractionation (HF) radiation regimens are equivalent to conventional fractionation schemes (CF) with respect to both outcomes and toxicity. Despite the cost savings associated with HF and the highly publicized endorsements by major regulatory organizations, adoption of these regimens has been slow. We reviewed use of HF in one cancer care network in an attempt to identify potential predictors of utilization. Breast cancer patients treated within our cancer care network with external-beam radiation following lumpectomy in 2016 were evaluated. Exclusion criteria included male gender, bilateral breast cancer, requirement of a third field to the supraclavicular nodes, and partial breast irradiation. For purposes of data collection, radiation courses with a dose per fraction > 2 Gy were considered HF, whereas those ≤ 2 Gy were considered CF. Patient, provider and tumor characteristics were categorized by use of HF and compared between groups using a chi-square test or 2-tailed t-test. A total of 233 consecutive patients were identified that met aforementioned criteria. All 69 patients treated at the main academic site received HF. For patients treated at community-based facilities, there was significant variation among the providers, with use of HF ranging from 25.9% to 89.7% (p<0.001). Referral from an academic versus community based surgeon was not associated with HF for the entire group. However, for individual providers there was significant bias for HF when referring surgeon was academic, 62.5% vs 10.5% (p=0.01). The use of HF occurred in 72.4%, 48.5%, and 28.2% of patients respectively for grade 1, 2, and 3 tumors. Thirty-five percent of patients receiving chemotherapy underwent HF as compared to 58% for patients without chemotherapy (p=0.01). 58% percent of stage I patients and 32% of stage II patients received HF radiation (p=0.03). Age and tumor subtype did not significantly impact use of HF (p=0.15, p=0.17). Furthermore, only 60.4% of patients over 70 and 54.6% of hormone positive patients receiving HF. The use of HF was 59.6% in patients who were combined hormone positive, over 50, and not receiving chemotherapy. There was increased use of HF after the implementation of institutional-wide prospective peer-review, 51.3% vs 61.1%, though this was not statistically significant (p=0.44). Despite level I evidence supporting the safety and efficacy of HF, significant variation in its use persists among providers. Despite strong guidelines supporting HF in patients over 50 with T1-2N0 disease, not receiving chemotherapy, a significant proportion of patients treated at our center continue to receive CF. Increased awareness and oversight through educational conferences such as peer-review may be useful in improving compliance to HF.