Predictors of clinically significant bleeding in colorectal cancer: Results from a global prospective cohort study

558 Background: Bleeding is an important complication among patients with colorectal cancer but its prevalence and predictors are incompletely understood. We evaluated data from a global prospective cohort study to define the incidence, predictors and consequences of bleeding in patients undergoing adjuvant or palliative treatment for colorectal cancer. Methods: CANTARISK was a prospective, non-interventional, international cohort study in patients with lung and colorectal cancer on chemotherapy, the patients were not on long term anticoagulation. Clinical data were collected at baseline, and at 2, 4, and 6 months. All data were compiled centrally and analyzed after the study had closed. Statistically significant univariable associations and a priori variables were tested in multivariable models; adjusted odds ratios (OR) with confidence intervals (CIs) are presented. Results: A total of 1,789 patients with colorectal cancer were enrolled from 2011-12. Median age was 62 years; 61% were male; 71% were Caucasian and 18% were Asian; 37% were from Europe, 28% from North America, 23% from Asia, and 12% from South America. Ninety-two (5.14%) patients experienced at least one bleeding episode during antineoplastic treatment, ranging from 1 to 5 episodes each, with a total of 109 episodes. The gastrointestinal tract was the source in 49 (45%) episodes. Approximately one-third of episodes (n=34, 31%) necessitated transfusion, but only 1 (0.9%) was fatal. In multivariate analysis, independent predictors of bleeding included presence of metastases (OR = 2.13, 95% CI=1.25-3.65) and surgery within prior 6 months (OR = 3.66, 95% CI=1.78-7.47) but not intact primary tumor (OR = 1.57, 95% CI=0.99-2.51). Notably, age, baseline blood counts, ECOG performance score, and anticoagulant use during study were not associated with bleeding. Conclusions: Bleeding is prevalent amongst patients with colorectal cancer receiving systemic chemotherapy. Post-surgical patients and those with metastatic disease appear to be at highest risk. Resection of the primary tumor does not appear to significantly alter risk.