Published online Feb 28, 2023. doi: 10.3748/wjg.v29.i8.1289
Peer-review started: November 19, 2022
First decision: December 10, 2022
Revised: December 18, 2022
Accepted: February 15, 2023
Article in press: February 158, 2023
Published online: February 28, 2023
Processing time: 100 Days and 17.4 Hours
Colorectal cancer (CRC) is one of the most prevalent malignancies worldwide. Although most prevalent among older people, its incidence above 50 years old has been decreasing globally in the last decades, probably as a result of better screening. Paradoxically, its incidence in patients below 50 years old [early-onset CRC (EO-CRC)] has been increasing, for reasons not yet fully understood. EO-CRC’s increasing incidence is genre independent but shows racial disparities and has been described to occur worldwide. It follows a birth-cohort effect which probably reflects a change in exposure to CRC risk factors. Its incidence is predicted to double until 2030, which makes EO-CRC a serious public health issue. Both modifiable and non-modifiable risk factors have been identified - some are potential targets for preventive measures. EO-CRC is often diagnosed at advanced stages and histological features associated with poor prognosis have been described. EO-CRC presents some distinctive features: Microsatellite in-stability is common, but another subtype of tumours, both microsatellite and chromosome stable also seems relevant. There are no age-specific treatment protocols and studies on EO-CRC survival rates have shown conflicting data. Due to the higher germline pathological mutations found in EO-CRC patients, an accurate genetic risk evaluation should be performed. In this review, we summarize the current evidence on epidemiological, clinical, histopathological and molecular features of EO-CRC and discuss the contribution of genetics and lifestyle risk factors. We further comment on screening strategies and specific dimensions to consider when dealing with a younger cancer patient.
Core Tip: The incidence of early-onset colorectal cancer (EO-CRC) has been surprisingly increasing worldwide and it has become a public health issue. Its clinical, genetic, molecular and histological characteristics suggest that this may be a distinct entity, with a more aggressive behaviour. However, both genetic and environmental risk factors seem to contribute to this observed epidemiological shift in CRC incidence. More evidence is needed in order to clarify EO-CRC aetiology and to develop screening and management strategies.