Differential Use of Radiotherapy Fractionation Regimens in Prostate Cancer

Abstract

ImportanceTechnical advances in treatment of prostate cancer and a better understanding of prostate cancer biology have allowed for hypofractionated treatment courses using a higher dose per fraction. Use of ultrahypofractionated stereotactic body radiotherapy (SBRT) has also been characterized.ObjectiveTo characterize US national trends of different RT fractionation schemes across risk groups of prostate cancer.Design, Setting, and ParticipantsThis retrospective cohort study used data collected by the National Cancer Database (NCDB) to characterize the fractionation regimens used for 302 035 patients diagnosed as having prostate cancer from January 1, 2004, to December 31, 2020, who underwent definitive RT. The analysis was performed between February 1 and April 30, 2023.ExposureStereotactic body RT or ultrahypofractionation, defined as 5 or fewer fractions of external beam RT (EBRT), moderate hypofractionation, defined as 20 to 28 fractions of EBRT, or conventional fractionation, defined as all remaining EBRT fractionation schemes.Main Outcomes and MeasuresTemporal trends and clinical and sociodemographic factors associated with SBRT, moderate hypofractionation, and conventional fractionation use.ResultsA total of 302 035 men receiving EBRT for localized prostate cancer between 2004 and 2020 were identified (40.1% aged 60-69 years). Black patients comprised 17.6% of this cohort; White patients, 77.9%; and other races and ethnicities, 4.5%. Patients with low-risk disease comprised 17.5% of the cohort; favorable intermediate-risk disease, 23.5%; unfavorable intermediate-risk disease, 23.9%; and high-risk disease, 35.1%. Treatment consisted of conventional fractionation for 81.2%, moderate hypofractionation for 12.9%, and SBRT for 6.0%. The rate of increase over time in patients receiving SBRT compared with conventional fractionation was higher (adjusted odds ratio [AOR] for 2005 vs 2004, 3.18 [95% CI, 2.04-4.94; P < .001]; AOR for 2020 vs 2004, 264.69 [95% CI, 179.33-390.68; P < .001]) than the rate of increase in patients receiving moderate hypofractionation compared with conventional fractionation (AOR for 2005 vs 2004, 1.05 [95% CI, 0.98-1.12; P = .19]; AOR for 2020 vs 2004, 4.41 [95% CI, 4.15-4.69; P < .001]). Compared with White patients, Black patients were less likely to receive SBRT compared with conventional fractionation or moderate hypofractionation (AOR for conventional fractionation, 0.84 [95% CI, 0.80-0.89; P < .001]; AOR for moderate hypofractionation, 0.77 [95% CI, 0.72-0.81; P < .001]). Compared with 2019, patients treated with all fractionation regimens declined in 2020 by 24.4%.Conclusions and RelevanceIn this hospital-based cohort study of patients with prostate cancer treated with definitive EBRT, use of moderate hypofractionation and SBRT regimens for definitive prostate cancer treatment has increased from 2004 to 2020. Despite this increasing trend, findings suggest potential health care disparities for Black patients receiving EBRT for localized prostate cancer. The number of patients treated with EBRT in the year 2020 decreased, coinciding with official onset of the COVID-19 pandemic in March 2020.