# Adoption of Hypofractionated and Ultrahypofractionated Adjuvant Radiation Therapy for Breast Cancer Across Main and Community Centers Within a Single Healthcare System

## TL;DR

This study found that doctors at a main hospital adopted shorter radiation therapy schedules for breast cancer faster than those at community clinics between 2017 and 2022.

## Contribution

The study reveals faster adoption of hypofractionated radiation therapy at academic centers compared to community clinics within a single healthcare system.

## Key findings

- Use of standard fractionation decreased at both main and community centers from 2017–2019 to 2020–2022.
- The main center adopted hypofractionation more rapidly than community clinics for intact breast and chest wall treatments.
- A higher proportion of patients received hypofractionation at the main center compared to community sites in the later period.

## Abstract

After breast cancer surgery, many people receive radiation therapy, which can be delivered over many or few visits. We asked whether doctors at our main university hospital switched to shorter schedules faster than doctors at our eight community clinics. We reviewed all patients treated from 2017 to 2022 and grouped care into long courses (about 25 visits), short courses (about 15), and very short courses (5). We compared care before 2020 and after 2020 for treatment to the breast and to the chest area after breast removal surgery. Long courses became less common everywhere over time. By 2020–2022, the main hospital used long courses less often and short or very short courses more often than the community clinics. Shorter care can reduce time, travel, and cost for patients. A shared treatment guide could help make care more consistent across all sites.

Purpose/Objective(s): Adjuvant radiation therapy (RT) is an effective treatment in the management of patients with breast cancer. Evidence supports both standard fractionation and, more recently, moderate hypofractionation and ultra hypofractionation leading to a potential diversity of clinical practice. Whether or not physicians at main academic centers adopt hypofractionated regimens more readily than those working at community centers is not known. Practice patterns were analyzed within our large healthcare network comprising one main and eight community sites before and after 2020. Materials/Methods: Patients treated with adjuvant breast RT between 2017 and 2022 in our radiation oncology department were identified. Treatment techniques were evaluated: standard fractionation (25–28 fractions to 50–50.4 Gy), moderate hypofractionation (15–16 fractions to 40.05–42.56 Gy), and ultra hypofractionation (5 fractions of 26–30 Gy) for intact breast, partial breast, and chest wall cases. Use of each technique was compared between the main academic center (Main) versus eight community sites (Community) in two time periods, 2017–2019 and 2020–2022. Differences were assessed using z-ratios for the difference between independent proportions. Results: There was a statistically significant decrease in the use of standard fractionation for intact breast and chest wall cases from the early to the late period at both the community sites and the main center; however, a higher proportion of patients were treated with standard fractionation at the community sites versus the main center in the late period (7.8% community versus 2.0% main, p < 0.01 for intact breast and 80.7% community versus 37.4% main, p < 0.01 for chest wall). There was a statistically significant increase in the use of hypofractionation for intact breast and chest wall cases from the early to the late period at both the community sites and the main center; however, a higher proportion of patients were treated with hypofractionation at the main center versus the community sites during the late period (92.2% community versus 98.0% main, p < 0.01 for intact breast and 19.3% community versus 62.6% main, p < 0.01). Conclusions: The present study shows that recent trial evidence supporting the use of shorter RT treatments changed practice among providers more rapidly at our main academic center versus our community sites. The reasons for this difference are not known; however, standardization of treatment by implementation of an adjuvant RT treatment algorithm may facilitate uniform care among patients with breast cancer and we are investigating the impact of this approach.