Association of Short-Term Particulate Matter Exposure among 5-Year Cancer Survivors with Incident Cardiovascular Disease: A Time-Stratified Case-Crossover Study

The association of short-term particulate matter concentration with cardiovascular disease (CVD) among cancer survivors is yet unclear. Using the National Health Insurance Service database from South Korea, the study population consisted of 22,864 5-year cancer survivors with CVD events during the period 2015–2018. Using a time-stratified case-crossover design, each case date (date of incident CVD) was matched with three or four referent dates, resulting in a total of 101,576 case and referent dates. The daily average particulate matter 10 (PM10), 2.5 (PM2.5), and 2.5–10 (PM2.5–10) on the day of case or referent date (lag0), 1–3 days before the case or referent date (lag1, lag2, and lag3), and the mean value 0–3 days before the case or referent date (lag0–3) were determined. Conditional logistic regression was conducted to calculate the adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for CVD according to quartiles of PM10, PM2.5, and PM2.5–10. Compared to the 1st (lowest) quartile of lag0–3 PM10, the 4th (highest) quartile of lag0–3 PM10 was associated with higher odds for CVD (aOR 1.13, 95% CI 1.06–1.21). The 4th quartiles of lag1 (aOR 1.12, 95% CI 1.06–1.19), lag2 (aOR 1.09, 95% CI 1.03–1.16), lag3 (aOR 1.06, 95% CI 1.00–1.12), and lag0–3 (aOR 1.11, 95% CI 1.05–1.18) PM2.5 were associated with higher odds for CVD compared to the respective 1st quartiles. Similarly, the 4th quartile of lag0–3 PM2.5–10 was associated with higher CVD events (aOR 1.11, 95% CI 1.03–1.19) compared to the 1st quartile. Short-term exposure to high levels of PM may be associated with increased CVD risk among cancer survivors.