Abstract
AIM: Colorectal cancer (CRC) is one of the most prevalent cancers worldwide. Epidemiological evidence has identified Type 2 Diabetes Mellitus (T2DM) as a risk factor for CRC. This study aimed to evaluate the impact of T2DM, along with clinicopathological and socio-demographic factors, on long-term overall survival in a large, nationally representative cohort of CRC patients with T2DM. METHOD: A prospective cohort of 1186 CRC patients was analysed, approximately 20% of whom had a diagnosis of T2DM. Kaplan-Meier estimates and multivariable Cox proportional hazards models were used to assess overall survival. RESULTS: CRC patients with T2DM were more often older, had lower educational attainment, were former smokers, and presented higher comorbidity, right-sided tumours, prior symptoms, depressive symptoms, elevated Body Mass Index (BMI) and lower baseline quality of life (EORTC QLQ-C30 < 75). In multivariable analysis, the co-occurrence of T2DM and depression (p = 0.007; HR 1.77; 95% CI: 1.17-2.68) and low quality of life (p = 0.04; HR 1.42; 95% CI: 1.02-1.97) emerged as independent predictors of poorer long-term survival. CONCLUSION: Our findings highlight the compounded negative impact of T2DM and depression on overall survival in CRC patients. Their combined presence significantly worsens prognosis, underscoring the need for integrated care approaches that address both physical and mental health. Future research should explore targeted interventions for these comorbidities to improve long-term outcomes and quality of life in this high-risk population.