Emergency Diagnostic Phenotypes and Differential Survival in Colorectal Cancer: A Real-World Cohort Study.

Background/Objectives: Emergency presentation in colorectal cancer (CRC) is commonly regarded as a uniformly high-risk condition, although clinically distinct emergency phenotypes may carry substantially different prognostic implications. We aimed to characterise emergency diagnostic phenotypes, bowel obstruction, perforation, severe stenosis, and lower gastrointestinal bleeding, and to examine their associations with treatment allocation, perioperative mortality, and overall survival after adjustment for recorded covariates. Methods: We performed a retrospective, real-world cohort study of 1051 consecutive patients with CRC diagnosed between 2018 and 2021 at a tertiary referral centre. Patients were assigned to four mutually exclusive groups using a classification defined before outcome analysis (obstructive-perforative, stenotic, haemorrhagic, elective). Overall survival was assessed using Kaplan-Meier analysis and multivariable Cox regression, with formal testing of the proportional hazards assumption. Results: Emergency presentation occurred in 43.7% of patients but was markedly heterogeneous. Metastatic burden did not differ across phenotypes (p = 0.122). The obstructive-perforative phenotype showed the least favourable outcomes: perioperative mortality was 11.5%, and it remained associated with mortality after adjustment for recorded covariates (HR 1.58, 95% CI 1.25-2.00; p < 0.001), with hazard ratios ranging from 1.33 to 1.69 across six model specifications. Haemorrhagic presentation was rectal-predominant and behaved favourably, with survival comparable to elective diagnosis. Among 30-day survivors, the excess hazard was attenuated but persisted (HR 1.39, 95% CI 1.04-1.86). Conclusions: Emergency presentation in CRC is not a monolithic risk category. Recognising the presenting phenotype may offer a pragmatic framework for provisional risk characterisation at diagnosis, but external validation and adjustment for patient-level comorbidity and performance status are required before routine clinical use.