ABSTRACT
OBJECTIVE: To investigate associations between air particulate matter of ≤2.5 µm in diameter (PM2.5 ) and ovarian cancer. DESIGN: County-level ecological study. SETTING: Surveillance, epidemiology, and end results from a collection of state-level cancer registries across 744 counties. Data from the Environmental Protection Agency's network for PM2.5 monitoring was used to calculate trailing 5- and 10-year PM2.5 county-level values. County-level data on demographic characteristics were obtained from the American Community Survey. POPULATION: A total of 98 751 patients with histologically confirmed ovarian cancer as a primary malignancy from 2000 to 2016. METHODS: Generalised linear regression models were developed to estimate the association between PM2.5 and PM10 levels, over 5- and 10-year periods of exposure, and ovarian cancer risk, after accounting for county-level covariates. MAIN OUTCOME MEASURES: Risk ratios for associations between ovarian cancer (both overall and specifically epithelial ovarian cancer) and PM2.5 levels. RESULTS: For the 744 counties included, the average PM2.5 level from 1990 through 2018 was 11.75 µg/m3 (SD = 3.7) and the average PM10 level was 22.7 µg/m3 (SD = 5.7). After adjusting for county-level covariates, the overall annualised ovarian cancer incidence was significantly associated with increases in 5-year PM2.5 (RR = 1.11 per 10 units (µg/m3 ) increase, 95% CI 1.06-1.16). Similarly, when the analysis was limited to epithelial cell tumours and adjusted for county-level covariates there was a significant association with trailing 5-year PM2.5 exposure models (RR = 1.12 per 10 units increase, 95% CI 1.08-1.17). Likewise, 10-year PM2.5 exposure was associated with ovarian cancer overall and with epithelial ovarian cancer. CONCLUSIONS: Higher county-level ambient PM2.5 levels are associated with 5- and 10-year incidences of ovarian cancer, as measurable in an ecological study.
