Living in ecologically compromised regions can significantly increase the risk of malignant neoplasms in the female reproductive system, including uterine body cancer (UBC). This study aimed to calculate the relative risk (RR) and the frequency of primary incidence of UBC among women aged 41–60 years living in areas with different levels of exposure to radiation, chemical, and combined environmental factors. The analysis considered high-, moderate-, and low-grade forms of UBC over a 20-year period (2000–2019). Information for the study was provided by Bryanskstat (Bryansk Region Statistical Bureau), Bryansk Regional Oncological Dispensary, Rospotrebnadzor and Rostechnadzor. We found that the RR of initial occurrence of high-grade forms of UBC in women living in ecologically compromised regions was considerably higher than that in female population of ecologically safe (control) territories, reaching the mean value of 1.28 (95% CI: 1.00–1.64); p = 0.047). Other findings include an increased RR of occurrence of both high- and, to a greater extent, low-grade forms of UBC in areas with high radioactive and chemical contamination — 1.19 (95% CI: 0.87–1.63) and 1.36 (95% CI: 0.70–2.65), respectively; the relative risks for combined and chemical contamination areas were 1.18 (95% CI: 0.90–1.55) and 1.34 (95% CI: 0.75–2.39), respectively; no increase was observed between the territories with combined and radioactive contamination — 0.99 (95% CI: 0.67–1.46) and 0.98 (95% CI: 0.44–2.21). In all likelihood, the data from this study indicate that accident-related radiation contamination plays a more significant role in the development of high-grade — and especially low-grade — forms of UBC than does chemical contamination.