Multiple primary tumours in early-onset colorectal cancer: deciphering the risk

Résumé fourni par la source

The prevalence of multiple primaries (MPs) in the same individual is reported to range from 2% to 17%1–4. Aetiological factors that may predispose individuals to MPs can be grouped into host-related (for example inherited cancer syndromes), lifestyle, and environmental factors5. Additionally, cancer survivors may be susceptible to developing second primary malignancies due to various unique factors beyond cancer predisposition, such as specific tumour characteristics (for example microsatellite unstable tumours), environmental exposures, and the late effects of therapies. Furthermore, Caucasian ancestry, a younger age at index cancer diagnosis, lower stage at presentation, indolent clinical behaviour with longer survival, and a positive family history have also been associated with an increased risk6. MPs are defined as the presence of more than one synchronous or metachronous cancer in the same individual. For epidemiological studies, tumours are considered MP malignancies if they arise in different sites and/or have different histology or morphology. This definition helps to avoid misclassifying multifocal or multicentric tumours, metastases, or recurrences as MPs. A cancer is classified as the index cancer if there is no prior record of invasive cancer7. The two most used definitions for MPs are provided by the Surveillance, Epidemiology, and End Results (SEER) Program and the International Association of Cancer Registries/International Agency for Research on Cancer (IACR/IARC)1. One notable difference is that the IACR/IARC considers several topography code groups as a single site; for example, the colon is considered one site by IACR/IARC, whereas the SEER Program treats tumours in different parts of the colon as distinct primaries. According to the SEER Program’s definition for the colon, a distinction should also be made between synchronous colorectal cancer (SCRC) and metachronous colorectal cancer (MCRC).

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