Analysis based on the opportunities for detecting huge numbers of consecutive colorectal cancers would help identify the reality of clinical practices

The article by Sekiguchi et al.¹ shows that there is a reality of opportunities for detecting colorectal cancers (CRCs) by a prospective case study with questionnaires of consecutive CRC patients at multiple hub hospitals for cancer treatment. More than thousands of CRC patients were collected within only 1 year. Huge numbers of CRCs would help the comparisons of backgrounds of detected CRCs, even though they were only case studies, essentially.

This study showed that nonscreening-detected CRC occupied more than 60% of CRCs, which may indicate that CRC screening in Japan does not function well. A US study found that the screening rate reached 71.8% of citizens aged 50–75 in 2021 and was promoted up to 74.4% as a “healthy people 2030 target.”² The increase in screening-detected CRC would also be one of the successful indicators of screening projects in the real world. The screening-detected CRCs critically showed less advanced invasions compared with nonscreening-detected CRCs in this article, too.

The other important issue is several types of interval CRC (iCRC). First of all, CRC detected within 1 year after positive fecal immunochemical test (FIT) with noncompliance to colonoscopy showed more advanced features, such as more invasions, metastasis, and more invasive treatment, as well as the tendency with left side by location and male by sex, which were more similar with symptomatic CRC, compared with FIT-iCRC, which is defined as CRC detected after a negative FIT and before the next recommended test is due and 3-year postcolonoscopy CRC (PCCRC-3 yr), which is defined as CRC diagnosed within 3 years after a colonoscopy with no cancer. These findings emphasize that the patients with FIT-positive results should be treated cautiously and quickly, and that the high quality of the colonoscopy procedure should be performed to prevent FIT-iCRC and PCCRC-3 yr.

FIT-iCRC and PCCRC-3 yr showed a nonnegligible proportion of detected CRCs and a higher proportion of BRAF mutations, which may include different biological features than other types of CRCs. In addition, these findings indicate that serrated lesions and nonpolypoid lesions, such as laterally spreading tumor, are one of the major candidates for interval cancers.³ These lesions would be needed to investigate the nature of progression.

This study collected huge numbers of CRCs, which may confirm generalizability. Fundamentally, the study design was prospective, and also a consecutive case study in major hub cancer treatment hospitals, which may include some bias. The history of previous findings of colonoscopies in addition to intervals and a history of FIT and colonoscopy also may influence the prevalence of interval cancers. Probably, the next step would be to clarify the magnitude of interval cancer in daily practices by using big real-world data, including control data, which would verify the real proportions of FIT-iCRC and PCCRC-3 yr and their biological and clinical characteristics.

The author declares no conflict of interest for this article.

None.