Age, Operative Intent, and Mortality After Emergency Colorectal Cancer Surgery: An Exploratory Analysis of Age-Related Patterns

Background: Emergency surgery for complicated colorectal cancer (CRC) presenting with obstruction, perforation, or uncontrolled bleeding has high postoperative mortality, especially in older patients. However, age-related risk and the roles of radical versus palliative treatment are not fully understood. This study aimed to measure 90-day and 36-month mortality after emergency CRC surgery and to analyze whether the relationship between age and mortality is nonlinear and influenced by operative intent. Methods: Retrospective cohort of consecutive adults undergoing emergency surgery for complicated CRC (2015-2024). The outcome was 90-day and 36-month all-cause mortality. Cox regression provided adjusted hazard ratios (HR) using two models: a primary whole-cohort model omitting pathological T/N stage, and a secondary resection-only model including pathological stage. Age was modeled with restricted cubic splines and predicted 90-day and 36-month mortality were plotted by operative intent. Results: In 496 patients, 90-day mortality was 19.7% (98/496), while 36-month mortality was 37.3% (185/496). In the primary whole-cohort Cox model, independent predictors of 36-month mortality included age ≥75 years (HR 2.09, 95% CI 1.48-2.95, p < 0.001), Charlson Comorbidity Index (HR 1.02, 95% CI 0.98-1.06, p = 0.31), obstruction (HR 1.69, 95% CI 1.18-2.42, p = 0.004), perforation (HR 2.05, 95% CI 1.24-3.39, p = 0.005), and metastatic disease (HR 2.30, 95% CI 1.62-3.27, p < 0.001); radical operative intent was independently associated with lower 36-month mortality (HR 0.461, 95% CI 0.30-0.71, p = 0.001). In a secondary resection-only model additionally adjusting for pathological T/N stage (n = 426 with available pathology), the association for radical intent was attenuated and no longer statistically significant (HR 0.67, 95% CI 0.43-1.03, p = 0.067). The 36-month mortality spline estimate indicated an increasing risk with advancing age; a likelihood-ratio test did not show that the spline model fit significantly better than a linear age term (χ2 = 1.43, df = 1, p = 0.233), so this pattern is interpreted descriptively rather than as formal evidence of nonlinearity, and no formal interaction between age and operative intent was demonstrated. Conclusions: Ninety-day mortality after emergency colon cancer surgery remains significant. Age-related risk shows a predominantly monotonic, descriptive pattern and should not be assumed to vary by operative intent without formal interaction testing, emphasizing individualized risk assessment and shared decision-making.