Risk of arterial and venous thromboembolic events among patients with colorectal carcinoma: a real-world, population-based study

Objective: To assess real-world patterns of arterial and venous thromboembolism among patients with colorectal carcinoma. Methods: The Alberta provincial cancer registry and other provincial medical records were used to identify patients with colorectal cancer (2004-2018) with no preceding or succeeding cancer diagnosis. The incidence of both arterial and venous thromboembolism in this patient population as well as factors associated with these thromboembolic events were examined through logistic regression analysis. Results: A total of 17,296 patients were found eligible and were included into the current study. We observed that 1564 patients (9%) experienced a thromboembolic event and 15,732 patients (91%) did not. The following factors were associated with any thromboembolic event: male sex (odds ratio [OR]: 1.20; 95% CI: 1.08-1.34), higher comorbidity (OR: 1.36; 95% CI: 1.31-1.41), metastatic disease (OR for nonmetastatic vs metastatic disease: 0.53; 95% CI: 0.47-0.60), living within North zone (OR for Edmonton zone vs North zone: 0.70; 95% CI: 0.59-0.84), treatment with fluoropyrimidines (OR for no fluoropyrimidines vs fluoropyrimidines: 0.53; 95% CI: 0.47-0.60) and treatment with bevacizumab (OR: for no bevacizumab vs bevacizumab: 0.53; 95% CI: 0.47-0.60). Factors associated with venous thromboembolism include, younger age (continuous OR with increasing age: 0.99; 95% CI: 0.98-0.99), higher comorbidity (OR: 1.10; 95% CI: 1.04-1.17), metastatic disease (OR for nonmetastatic disease vs metastatic disease: 0.40; 95% CI: 0.35-0.47), North zone (OR for Edmonton zone vs North zone: 0.70; 95% CI: 0.56-0.86), treatment with fluoropyrimidines (OR for no fluoropyrimidines vs fluoropyrimidines: 0.45; 95% CI: 0.39-0.53) and treatment with bevacizumab (OR for no bevacizumab vs bevacizumab: 0.73; 95% CI: 0.58-0.93). Conclusion: Thromboembolic events are not uncommon among colorectal cancer patients, and the risk is increased with male sex, higher comorbidity, presence of metastatic disease, living within the North zone of the province (where there is limited access to tertiary care centers) and treatment with fluoropyrimidines or bevacizumab.Lay abstract In this analysis of patients who have been diagnosed of colon and rectal cancers in Alberta, Canada, development of blood clots was not uncommon. Certain patient and treatment risk factors seem to increase the risk of this phenomenon.