BACKGROUND: Fatalistic beliefs may be implicated in longer help-seeking intervals, and consequently, greater risk of advanced stage at cancer diagnosis. METHODS: We examined associations between fatalism and stage at diagnosis in a population-based cohort of 4,319 U.S. patients with newly diagnosed lung or colorectal cancer participating in the Cancer Care Outcomes and Research Surveillance (CanCORS) study. Fatalistic beliefs were assessed with an established measure. A fatalism score (range, 4-16) was created by summing Likert scale responses to four items. Cancer stage at diagnosis was abstracted from medical records by trained staff. Logistic regression was used to assess the association between fatalism score and advanced stage at diagnosis (IV vs. I-III), adjusting for sociodemographic and clinical characteristics. RESULTS: Overall, 917 (21%) patients had stage IV cancers (lung: 28%, colorectal: 16%). The mean fatalism score was 10.7 (median = 11; interquartile range, 9-12). In adjusted analyses, a higher fatalism score was associated with greater odds of stage IV diagnosis (OR per unit increase in fatalism = 1.05; 95% confidence interval 1.02-1.08; P = 0.003). Patients with the highest fatalism score had an adjusted 8.9% higher frequency of stage IV diagnosis compared with patients with the lowest score (25.4% vs. 16.5%). DISCUSSION: In this large and socioeconomically, geographically, and ethnically diverse population of patients with lung and colorectal cancer, fatalistic beliefs were associated with higher risk of advanced stage at diagnosis. Longitudinal studies are needed to confirm causation. IMPACT: These findings support the value of incorporating information about the curability of early-stage cancers in public education campaigns.