Surgery Utilization Mediates Survival in Patients With Dementia and Stage I-III Colorectal Cancer.

BACKGROUND: Dementia is associated with increased mortality among patients with colorectal cancer (CRC), and they receive less invasive evaluations, chemotherapy, and surgery. The objectives of this study were to (1) compare demographics and treatment patterns among individuals with CRC with and without dementia, and (2) evaluate the relationship between dementia, surgery receipt or refusal, and survival. METHODS: The Indiana Cancer Registry was reviewed (2000-2020) for adult patients with clinical Stage I-III CRC. The diagnosis of dementia was determined by the presence by ICD-9/10 codes. Overall survival was estimated using the Kaplan-Meier method and compared between patients with and without dementia using the log-rank test. To assess the extent to which the association between dementia and survival was mediated by surgery utilization, a regression-based causal mediation analysis of surgery receipt and refusal was performed, using covariates chosen a priori considered possible confounders of diagnosis, treatment, and survival. RESULTS: A total of 69,318 patients met the inclusion criteria; 1516 (2.1%) had dementia and 67,802 (97.8%) did not. The dementia cohort had a higher percentage of female patients (55% vs. 49%, p < 0.001) and was older, with a median age at diagnosis of 79 (vs. 69, p < 0.001). Patients without dementia had higher survival probabilities across all time points (12, 36, 60, 120, and 180 months), and the survival difference was statistically significant (p < 0.001). Receipt of surgery was a statistically significant mediator of survival in patients with dementia and CRC, with a proportion mediated of 9.6% (95% CI 6.2%-13.2%). CONCLUSION: Individuals with dementia and CRC receive lower rates of surgery with higher rates of refusal. Differences in surgical utilization are a significant mediator of survival differences, emphasizing the importance of patient-centered goals-of-care discussions with patients and family members to assess the benefits and burdens of surgical treatment when planning.