Chemoprevention of Colorectal Cancer-With Emphasis on Low-Dose Aspirin and Anticoagulants

Abstract

Background and Aims: Colorectal cancer (CRC) remains the third most common cancer worldwide and a leading cause of cancer-related death. Chemoprevention through widely used pharmaceutical agents has garnered increasing interest due to its potential cost-effectiveness and accessibility. This review summarizes current evidence from observational studies, randomized controlled trials, and meta-analyses on the association between commonly prescribed medications and CRC incidence and survival, with particular emphasis on low-dose aspirin and oral anticoagulants (OACs). Scope: Aspirin is the most extensively studied agent, with substantial evidence supporting its protective effect on CRC-specific survival, particularly in long-term users, those with COX-2 overexpression, or PIK3CA mutations. OACs have recently gained attention due to their association with increased gastrointestinal bleeding, which may facilitate earlier CRC detection. While emerging evidence suggests a possible survival benefit through this mechanism, data remain heterogeneous and affected by methodological challenges such as lead-time bias. Metformin is associated with improved CRC outcomes, primarily in patients with type 2 diabetes, though its direct anti-tumor potential remains under investigation. Corticosteroids, statins, and beta-blockers have both limited and inconclusive evidence. Finally, recent studies on vitamin D, calcium, and folic acid suggest inconsistent associations, often confounded by lifestyle factors or underlying comorbidities. Conclusions: While promising, chemoprevention strategies require further validation in well-designed, mechanistically informed studies that account for confounding variables, treatment duration, and tumor biology. Personalized prevention-guided by genetic, molecular, and clinical risk factors-represents a promising path forward.

Keywords: aspirin; chemoprevention; colorectal cancer; metformin; oral anticoagulation; pharmacoepidemiology.