Radiation therapy trends in advanced prostate cancer by age and geographic location: Analysis of SEER data.

179 Background: Radiation therapy (RT) is a key treatment modality in advanced prostate cancer, yet utilization patterns may vary by patient age and geography, potentially reflecting disparities in access and care quality. Methods: We conducted a retrospective cohort study using SEER 22 data from 2000 to 2020. Men aged 60 years and older diagnosed with high-risk prostate cancer, poorly differentiated, Grade III and undifferentiated, anaplastic, Grade IV were included. They were stratified by age groups (60–64, 65–69, 70–74, 75–79, 80–84, 85+) and geographic location (metropolitan based on population counts and nonmetropolitan counties) The primary outcome was receipt of RT, defined by the SEER "Radiation Recode" variable. Descriptive statistics were used to determine RT receipt by age group, and a Chi-square test was performed to assess statistical significance. Results: Among 409,868 patients, RT utilization in advanced prostate cancer varied by both age and geographic location. RT rates increased from approximately 32% in patients aged 60–64 to a peak of 48% in those aged 75–79 living in metropolitan areas with populations greater than 1 million. Similar trends were observed in smaller metropolitan areas, though with slightly lower RT rates. After age 79, RT utilization declined sharply across all regions, dropping to as low as 8–15% in patients aged 85 and older. Nonmetropolitan counties, not adjacent to metropolitan areas, consistently showed lower RT use across all age groups. These differences were statistically significant (p < 0.001, χ² test). Conclusions: RT utilization in advanced prostate cancer demonstrates an age-dependent pattern that varies by geographic location. Patients in larger metropolitan areas experience higher RT rates, with utilization peaking in the 75–79 age group before declining in older patients. Rural and less populated areas consistently show lower RT receipt across all ages. These findings highlight potential disparities in treatment access and delivery, underscoring the need for targeted interventions to improve equity in cancer care. Rates of RT based on age and geographic location. Age Group Metro >1M Metro 250k–1M Metro <250k Non-metro Adj Non-metro Not Adj 60–64 31.90% 30.60% 30.30% 30.90% 28.80% 65–69 37.70% 36.90% 35.70% 36.30% 32.90% 70–74 47.00% 46.00% 42.00% 44.00% 40.70% 75–79 48.00% 47.60% 41.70% 40.20% 41.20% 80–84 34.20% 32.60% 29.50% 25.70% 27.30% 85+ 14.50% 12.90% 10.90% 8.90% 8.20% p<0.001.