Lower Gastrointestinal Bleeding And Risk of Gastrointestinal Cancer.

OBJECTIVES: Lower gastrointestinal (GI) bleeding is a well-known symptom of colorectal cancer (CRC). Whether incident GI bleeding is also a marker of other GI cancers remains unclear. METHODS: This nationwide cohort study examined the risk of various GI cancer types in patients with lower GI bleeding. We used Danish medical registries to identify all patients with a first-time hospital diagnosis of lower GI bleeding during 1995-2011 and followed them for 10 years to identify subsequent GI cancer diagnoses. We computed absolute risks of cancer, treating death as a competing risk, and calculated standardized incidence ratios (SIRs) by comparing observed cancer cases with expected cancer incidence rates in the general population. RESULTS: Among 58,593 patients with lower GI bleeding, we observed 2,806 GI cancers during complete 10-year follow-up. During the first year of follow-up, the absolute GI cancer risk was 3.6%, and the SIR of any GI cancer was 16.3 (95% confidence interval (CI): 15.6-17.0). Colorectal cancers accounted for the majority of diagnoses, but risks of all GI cancers were increased. During 1-5 years of follow-up, the SIR of any GI cancer declined to 1.36 (95% CI: 1.25-1.49), but risks remained increased for several GI cancers. Beyond 5 years of follow-up, the overall GI cancer risk was close to unity, with reduced risk of rectal cancer and increased risk of liver and pancreatic cancers. CONCLUSIONS: A hospital-based diagnosis of lower GI bleeding is a strong clinical marker of prevalent GI cancer, particularly CRC. It also predicts an increased risk of any GI cancer beyond 1 year of follow-up.