UK recruits 250,000 participants to study early-onset bowel cancer

Cancer Research UK has announced the launch of PROSPECT, a large prospective cohort study aiming to recruit 250,000 participants in the United Kingdom. The study is designed to investigate the environmental, dietary, and lifestyle factors that may be driving an observed increase in colorectal cancer diagnoses in people under the age of 50 — a trend that has been documented in multiple high-income countries over recent decades.

The precise aetiology of early-onset colorectal cancer remains poorly understood. While hereditary syndromes such as Lynch syndrome and familial adenomatous polyposis account for a proportion of early-onset cases, the majority do not carry a high-penetrance germline predisposition variant, pointing to environmental and possibly gene–environment interaction effects as important contributors.

PROSPECT will collect detailed information on participants' diets, physical activity, gut microbiome, and other lifestyle exposures over time, linking these to cancer incidence data. Genetic data collection is expected to allow examination of polygenic risk in conjunction with modifiable risk factors.

For genetics researchers, the cohort will offer a resource for studying gene–environment interactions and the contribution of common and rare germline variation to early-onset colorectal cancer. For oncologists and genetic counsellors, the eventual findings may inform how hereditary and non-hereditary early-onset cases are distinguished in practice, though published guidance will be required before any clinical implications can be drawn.