Differential cardiovascular outcomes of radiotherapy in rectal, breast, and cervical cancer: insights from a SEER data analysis

Recent years have witnessed an increase in mortality and morbidity from chronic diseases unrelated to tumors in patients with malignant tumors. While radiation therapy reduces local tumor recurrence, it may elevate late mortality from cardiovascular diseases (CVD). The relationship between radiotherapy for cancer and CVD risk remains debated. This study analyzed the surveillance, epidemiology, and end results (SEER) Database from 1975 to 2014, focusing on long-term CVD observation periods of 1, 5, and 10 y. We tracked patients from cancer diagnosis to death or last follow-up, calculating hazard ratios (HRs) and 95% confidence intervals (CIs) for cardiovascular-specific survival (CVSS) using Fine-Gray binary competing risk regression analysis. Our analysis included 303 665 patients diagnosed with rectal (18 398), breast (276 263), and cervical (8004) cancers. Among these, 7098 (2.34%) died from CVDs. Rectal cancer patients undergoing radiotherapy, mainly in later stages, showed a reduced risk of CVD mortality (HR = 0.72, 95% CI: 0.61-0.84). Breast cancer patients treated with radiotherapy, who generally had smaller tumors, experienced significantly lower cardiovascular mortality (HR = 0.48, 95% CI: 0.46-0.51). Conversely, cervical cancer patients receiving radiotherapy had a higher rate of CVD mortality (HR = 2.14, 95% CI: 1.30-3.52). The AUC values for 3-y CVSS were 0.788, 0.837, and 0.821 for rectal, breast, and cervical cancers, respectively, indicating good predictive accuracy. The impact of tumor radiotherapy on CVD outcomes appears cancer-type specific, with cervical cancer radiotherapy increasing the risk of cardiovascular morbidity and mortality.