National practice patterns of adjuvant breast hypofractionated radiation therapy completion in early-stage breast cancer.

Abstract

e13500 Background: The seminal nationwide examination of treatment completion between standard fractionation radiation therapy (SFRT; typically 5-6 weeks) and hypofractionated radiation therapy (HFRT; typically 3-4 weeks) assessed both treatments from 2004–2015, revealing that HFRT yielded significantly superior completion rates. (PMID 32693964) We sought to assess whether these trends have persisted in wake of the COVID19 pandemic and the increased adoption of ultrahypofractionated (one-week) radiation therapy. Methods: Using the National Cancer Database, we identified women with early stage, node-negative, invasive breast cancer treated with lumpectomy followed by whole-breast RT from 2018 through 2022. We defined SFRT as a dose of 1.8–2.0 Gray (Gy) per fraction, HFRT as 2.66–2.70 Gy/fraction, and ultrahypofractionated radiation therapy (URT) as 5.2-6.0 Gy/fraction. Completion of RT was defined as receiving a total dose of at least 46 Gy for SFRT, 40 Gy for HFRT, and 26 Gy for URT. Multivariable logistic regression models were used to evaluate predictors including fractionation type and distance from treatment facility. Results: A total of 34,043 patients were identified, with 95.9% completing RT. A majority of patients underwent HFRT (81.7%) with 97.4% completing their radiation courses. 11.0% of patients underwent SFRT while 7.3% underwent URT. HFRT utilization was 79.42% in 2018 and 78.27% in 2022. Despite similar rates of HFRT use, there was a significant increase in URT in that time (0.26% 2018 to 17.52% 2022; p < 0.0001) Age (>60 vs <=60) was associated with URT adoption (p<0.0001), with those over 60 more frequently adopting URT. Distance from treatment center was also associated with fractionation regimen (p trend <0.0001), with people living farther away more frequently adopting URT. Conclusions: From 2018–2022, use of URT increased, while utilization of SFRT decreased, reinforcing the ongoing shift towards shorter-course treatment in this patient population. HFRT regimens continue to demonstrate improved completion rates compared with SFRT, with rates of URT increasing commensurate with SFRT decrease in early-stage breast cancer RT. Further assessment of the impact of the COVID19 pandemic on these trends is ongoing.