A Growing Specialty: A 15-year Profile of US Radiation Oncology Residency Growth and Implications for Workforce Imbalances

Abstract

The radiation oncology (RO) community is concerned about geographic maldistribution and a future oversupply of physicians, driven in part by a sustained growth in residency programs and positions. This growth has previously only been reported in absolute numbers of positions over time. Therefore, the aim of this project is characterize RO residency growth, in both number of programs and number of positions, as it relates to geographic region, major urban centers, and program size. A database of all RO programs & positions from 2003 to 2018 was created using publicly available data from the National Resident Matching Program (NRMP). Programs were categorized by geography (US Census Bureau region designations: Northeast [NE], South [SO], Midwest [MW], and West [WT]), location in a 2018 top metropolitan region (top 10 Combined Statistical Area [CSA] by population vs. all others), and program size (large [>6 trainees] vs. small [≤6 trainees]. Program size definition (large vs. small) was dynamic by year and thus defined as the cumulative number of positions over the prior four years. Linear regression with interaction terms was used to determine the effect of region, metro size, and program size on RO program & positions growth over time. An increase in the number of RO programs (54 to 91, 69%) & annual positions (106 to 193, 82%) was observed during the studied time frame. In decreasing regional order, 2018 programs & positions, respectively, are located in the SO (31.9% & 29.9%), NE (25.3% & 28.5%), MW (23.1% & 25.0%) and WT (19.8% & 16.7%). There is a statistically significant difference in regional RO program & position annual growth rate. Specifically, programs & positions in the NE (0.44 programs/year & 1.48 positions/year), SO (0.70 & 2.28), and WT (0.62 & 1.44) are increasing at faster annual rates relative to the MW (0.16 & 0.84) (all p<0.05). 41.7% of all programs and 48.0% of all positions are in a top metropolitan location. Annual growth rates in RO programs (0.86 vs. 1.04) & positions (2.73 vs. 3.31) were not statistically different between top metropolitan areas vs. all others (p >0.18). Larger programs (change in annual growth rate: 0.23 positions/year) are growing faster than smaller programs (change in annual growth rate: -1.89), p=0.01. In this study of US RO residency growth, we found steady and unequal growth rates among residency programs & positions over the past 15 years. This growth may worsen already existing imbalances in the workforce, including (1) Geographic: MW growing at rates slower than other more saturated regions, 2) Urban: the top urban areas are growing at equal rates as elsewhere, and 3) Size: larger, established programs are growing more rapidly than smaller programs. Further discussion regarding the implications of these imbalances is warranted.