Increasing incidence of colorectal cancer in young adults aged <50 years in England over the last 20 years

Introduction: Worldwide, colorectal cancer (CRC) is the 3rd most common cancer and the 2nd leading cause of cancer mortality – with an estimated 1.9 million new cases (10% of all cancers) and 935,000 deaths (9.4% of all cancers) in the year 2020. In recent decades, the incidence of early-onset CRC, (i.e., in persons aged <50 years) has been rising in many countries, whereas in older adults the incidence has stabilised. We conducted a retrospective population-based cohort study to examine changes in the incidence of CRC in England over the last four decades.

Material and method: Individual-level data for patients diagnosed with CRC during 1985-2019 were obtained from Public Health England. Average annual incidence rates (AAIRs) were calculated by sex and two age categories (<50 and 50+ years) during the seven 5-year time periods (1985-89 to 2015-19).

Results and discussion: During the 35-year study period, a total of 1,048,935 patients (54% males, 46% females) with CRC were registered in England. In young adults aged <50 years, the average annual number of cases increased from 1224/year in 1985-89 to 2209/year in 2015-19 (+80%); the AAIRs increased from 3.8/100,000 in 1985-89 to 6.3/100,000 in 2015-19 (+66%). This increase accelerated from 2000-04 onwards in both sexes. Whereas in older adults aged 50+ years, the AAIRs remained fairly stable during the study period with a nominal increase of 4%. During the recent 2010-17 period, 62% of the patients aged <50 years were diagnosed at an advanced Stage 3 or 4, compared to 55% of those aged 50+ years. There were relatively higher proportion of older adults aged 50+ years diagnosed at an early Stage 1 or 2, compared with those aged <50 years – suggesting that the benefit of early diagnosis due to screening/treatment of pre-malignant lesions is mainly in older adults aged 50+ years currently included in the screening criteria.

Conclusion: This large population-based study of over 1 million patients shows that the incidence of CRC in older adults aged 50+ years in England has stabilised (or levelled off) during the last 20 years, whereas there has been a steady increase in incidence in young adults aged <50 years during this period. It is suggested that the rising incidence of early-onset CRC in young adults aged <50 years may be attributed to diet, lifestyle factors, microbiome composition and genetic factors. This study supports the debate for lowering the bowel cancer screening age to facilitate early diagnosis and treatment of pre-malignant lesions in young adults aged <50 years.