Hereditary and Inflammatory Bowel Disease-Related Early Onset Colorectal Cancer Have Unique Characteristics and Clinical Course Compared with Sporadic Disease.

BACKGROUND Early onset colorectal cancer (EoCRC), diagnosed in those <50 years old, is increasing in incidence. We sought to differentiate characteristics and outcomes of EoCRC in patients with sporadic disease or preexisting conditions. METHODS We evaluated 2,135 patients with EoCRC in a population-based cohort from the Canadian province of British Columbia. Patients were identified on the basis of presence of hereditary syndromes (n = 146) or inflammatory bowel disease (IBD; n = 87) and compared with patients with sporadic EoCRC (n = 1,902). RESULTS Proportions of patients with preexisting conditions were highest in the youngest decile of 18-29 (34.3%, P < 0.0001). Patients with sporadic EoCRC were older, more likely female, and had increased BMI (P < 0.05). IBD-related EoCRC had the highest rates of metastatic disease, poor differentiation, adverse histology, lymphovascular, and perineural invasion (P < 0.05). Survival was lower in patients with IBD (HR, 1.80; 95% CI, 1.54-3.13; P < 0.0001) and higher in hereditary EoCRC (HR, 0.47; 95% CI, 0.45-0.73; P < 0.0001) compared with sporadic. Prognosis did not differ between ulcerative colitis or Crohn's disease but was lower in those with undifferentiated-IBD (HR, 1.87; 95% CI, 1.01-4.05; P = 0.049). Lynch syndrome EoCRC had improved survival over familial adenomatous polyposis (HR, 0.31; 95% CI, 0.054-0.57; P = 0.0037) and other syndromes (HR, 0.43; 95% CI, 0.11-0.99; P = 0.049). In multivariate analysis controlling for prognostic factors, hereditary EoCRC was unchanged from sporadic; however, IBD-related EoCRC had worse overall survival (HR, 2.21; 95% CI, 1.55-3.16; P < 0.0001). CONCLUSIONS EoCRC is heterogenous and patients with preexisting conditions have different characteristics and outcomes compared with sporadic disease. IMPACT Prognostic differences identified here for young patients with colorectal cancer and predisposing conditions may help facilitate treatment planning and patient counseling.See related commentary by Hayes, p. 1775.