Young-onset colorectal cancer in New South Wales: a population-based study.

Objective: Australia has the highest incidence of colorectal cancer (CRC) in the world. The incidence of young-onset CRC (yCRC) is increasing in developed nations. Our aim was to determine the incidence of yCRC in New South Wales, the demographic and clinico-pathological characteristics of these patients, and their survival.

Design, Setting, Participants: A population-based cohort study of all cases of CRC diagnosed in NSW during 2001-2008. Data on newly diagnosed cases of CRC were obtained from the NSW Central Cancer Registry; mortality data were obtained from the NSW Registry of Births Deaths and Marriages (to 2012). The characteristics and tumour-related factors of patients under 50 years of age (yCRC) were compared with those for patients aged 50 years or more.

Main Outcome Measures: Current incidence of yCRC and trends in incidence; 5-year cancer-specific survival rates and risks of death compared with older patients.

Results: 32 178 patients were diagnosed with CRC, including 2001 (6.2%) with yCRC. The incidence of yCRC was unchanged across the study period (2001, 13.7 cases per 100 000 population; 2008, 11.8 per 100 000; P = 0.26). Rectal cancer was more frequent in yCRC than in older patients (34.4% v 26.0%), as was distant disease (21.2% v 15.3%). However, 5-year cancer-specific survival was greater for patients with yCRC (68.8%; 95% CI, 66.2-71.2%) than for older patients (66.3%; 95% CI, 65.6-67.0%; P < 0.001).

Conclusions: The incidence of yCRC did not increase in NSW during 2001-2008. Despite more advanced disease at presentation, cancer-specific survival was better than for older patients with CRC.