P. Sirimanna1, Y. Y. Lee1, M. K. Suen1, N. Nassar1,2, M. A. Gladman1 1Sydney Medical School – Concord, University Of Sydney,Academic Colorectal Unit,Sydney, NSW, Australia 2The Kolling Institute, University Of Sydney,Clinical And Population Perinatal Health Research,Sydney, NSW, Australia
Introduction:
Young-onset colorectal cancer (yCRC) has been shown to be increasing in incidence in population-based studies performed in North America. Further, such studies have shown that it occurs more commonly on the left side and is more advanced at presentation. However, there are limited population-based studies of yCRC in Australia. Therefore, the aim of this study was to determine the incidence, trends, tumor location and stage and survival of patients with yCRC in Australia.
Methods:
We conducted a population-based cohort study of all CRC diagnosed in New South Wales, Australia, 2001-2008. Data was ascertained via record-linkage of statutory Cancer Registry and Registered Deaths data collections. yCRC was defined as CRC in patients <50 years and their characteristics and tumor-related factors compared with patients diagnosed with CRC and aged 50+ years. Age-sex standardized incidence rates and trends were examined using Poisson regression analysis. The five-year cancer-specific survival rate for yCRC patients was compared to that aged 50+ years, and then stratified by tumor stage and within various age groups of yCRC patients.
Results:
Overall, there were 34,119 patients diagnosed with CRC in 2001-2008. yCRC occurred in 6.2% of cases (n=2,128; 1,101 males [51.7%]), whilst the remaining 31,991 cases (n=17,860, 55.8% males) were diagnosed in patients aged 50+ years. The incidence of yCRC declined slightly throughout the study period from 13.7 per 100,000 in 2001 to 11.8 per 100,000 in 2008; P=0.57). Inflammatory bowel disease was present in 3.3% (n=70) of patients with yCRC compared to 1.2% (n=395) of patients aged 50+ years (P<0.001). The tumor was located in the right colon in only 19.2% (n=408) of yCRC patients (versus 28.2% [n=9,029] in 50+ years), instead favoring the rectum (34.6% [n=736] versus 26.1% [n=8,342] in 50+ year olds, P<0.001). Five-year cancer-specific survival was superior in yCRC patients (68.9%; 95% CI 66.3%-71.2%) compared with patients 50+ years (65.8%; 95% CI 65.1%-66.5%; P<0.001), despite more metastatic disease at presentation (21.9% [n=466] versus 15.2% [n=4,873] in 50+ years, P<0.001). Further stratification revealed that five-year cancer-specific survival was similar in yCRC patients aged <40yrs (68.0%; 95% CI 62.9%-72.5%) and patients aged 40-50yrs (69.2%; 95% CI 66.2%-71.9%) (P=0.68).
Conclusion:
This population-based study has revealed that, unlike in North America, the incidence of yCRC is not increasing in Australia. Consistent with North American studies, yCRC tends to occur more commonly in the rectum than in the proximal colon and is more advanced at presentation in Australia. Cancer-specific survival is superior compared to older patients.