Early-onset colorectal cancer: why it should be high on our list of differentials

Early-onset colorectal cancer (EOCRC) (<50 years) incidence has increased in Australia and worldwide. However, the diagnosis of EOCRC is often delayed. Recent research has discovered some differences from later-onset colorectal cancer (LOCRC) (>50 years). An awareness of the unique features of EOCRC is crucial to reduce time from symptom onset to diagnosis.

A literature search was conducted on electronic databases (MEDLINE, EMBASE and Cochrane Library) using the search terms "early onset colorectal cancer" or "young onset colorectal cancer."

The American Cancer Society has reduced the colorectal cancer screening initiation age to 45 for average-risk adults whilst screening programmes in the United Kingdom and Australia remain unchanged with initiation at 60 and 50, respectively. Exposures resulting in dysbiosis (obesity, westernised diet, alcohol, antibiotic and sugar-sweetened beverage consumption) have been linked with increased EOCRC risk. EOCRC is often left-sided presenting with rectal bleeding, altered bowel habit and constitutional symptoms. EOCRC is more commonly sporadic than hereditary, harbouring different genetic mutations than LOCRC. Comparative survival outcomes of EOCRC and LOCRC are conflicting with studies suggesting either better or poorer survival. Young patients better tolerate treatment-related toxicities, which may account for their improved survival despite comparatively advanced stages and poorer histopathological features at diagnosis.

Current EOCRC literature is limited by American-focused datasets and heterogenous EOCRC definitions and study designs (the greatest strength of evidence exists for EOCRC risk factor studies comprised of large retrospective cohorts). There is minimal research into the quality of life and surgical outcomes of EOCRC patients, and this area warrants further investigation.