NTRK oncogenic fusions are exclusively associated with the serrated neoplasia pathway in the colorectum and begin to occur in sessile serrated lesions

Background: NTRK fusions are emerging tissue-agnostic drug targets in malignancies including colorectal cancers (CRCs), but their detailed landscape in the context of various colorectal carcinogenesis pathways remains to be investigated. Methods: Pan-TRK expression was assessed by immunohistochemistry in retrospectively collected colorectal epithelial tumor tissues, including 441 CRCs (133 microsatellite instability-high (MSI-high) and 308 microsatellite stable (MSS)) and 565 premalignant colorectal lesions (300 serrated lesions and 265 conventional adenomas). TRK-positive cases were subjected to next-generation sequencing and/or fluorescence in situ hybridization to confirm NTRK rearrangements. Results: TRK positivity was not observed in any of the MSS CRCs, conventional adenomas, traditional serrated adenomas, or hyperplastic polyps, whereas TRK positivity was observed in 11 of 58 (19%) sporadic MSI-high CRCs, 4 of 23 (17%) sessile serrated lesions with dysplasia (SSLDs), and 5 of 132 (4%) SSLs. The 11 TRK-positive MSI-high CRCs commonly harbored CpG island methylator phenotype-high (CIMP-high), MLH1 methylation, KRAS/BRAF wild-type, and NTRK1 or NTRK3 fusion (TPM3-NTRK1, TPR-NTRK1, LMNA-NTRK1, SFPQ-NTRK1, ETV6-NTRK3, or EML4-NTRK3). Both NTRK1 or NTRK3 rearrangement and KRAS/BRAF wild-type were detected in all nine TRK-positive SSL(D)s, seven of which demonstrated MSS and/or CIMP-low. TRK overexpression and early dysplastic changes are occasionally co-localized in the crypt base area of SSLs. Age-related occurrence patterns suggest that the progression interval from NTRK-rearranged SSLs to CRCs may be shorter than from BRAF-mutated SSLs to CRCs. Conclusion: NTRK-rearranged colorectal tumors develop exclusively through the serrated neoplasia pathway and can be initiated from non-dysplastic SSLs without KRAS/BRAF mutations prior to full occurrence of MSI-high/CIMP-high.

Nut and peanut butter intake and the risk of colorectal cancer and its anatomical and molecular subtypes: the Netherlands Cohort Study

Nut intake has been associated with reduced total cancer-related mortality, but evidence for colorectal cancer (CRC) risk is inconclusive. We investigated the associations between nut and peanut butter intake and anatomical CRC subtypes. To account for molecular heterogeneity, associations between nut and peanut butter intake and colorectal tumors harboring APC, KRAS or BRAF mutations, p53 overexpression or microsatellite instability were examined in secondary analyses. In the Netherlands Cohort Study (n = 120 852), lifestyle habits were measured with a questionnaire in 1986. After 20.3 years follow-up, 3567 CRC cases were included in case–cohort analyses. For the analyses of molecular CRC subtypes, 574 cases were included after 7.3 years follow-up. In categorical analyses, total nut intake was not significantly associated with CRC [HR (95% CI) 10+ g/day versus non-consumers = 0.94(0.78–1.15) in men; 0.96(0.75–1.22) in women]. In restricted cubic spline analyses, significant non-linear inverse associations with rectal cancer were observed for total nut, peanut and peanut butter intake in women, and borderline significant non-linear inverse associations for total nut and peanut intake in men. Regarding the molecular CRC subtypes, peanut butter intake was significantly associated with an increased risk of colorectal tumors that did not develop through the serrated neoplasia pathway in men [HR (95% CI) per 5 g/day increment = 1.22(1.07–1.38)]. Nut and peanut butter intake are non-linearly inversely associated with rectal cancer risk in women. In men, nut intake is borderline significantly non-linearly associated with a reduced rectal cancer risk. Peanut butter is associated with an increased risk of colorectal tumors that do not develop through the serrated neoplasia pathway in men.

Curriculum review: serrated lesions of the colorectum

Colorectal cancer (CRC) is the second leading cause of death from cancer in the UK. Sporadic CRC evolves by the cumulative effect of genetic and epigenetic alterations. Typically, over the course of several years, this leads to the transformation of normal colonic epithelium to benign adenomatous polyp, low-grade to high-grade dysplasia and finally cancer—the adenoma-carcinoma sequence. Over the last decade, the serrated neoplasia pathway which progresses by methylation of tumour suppressing genes has been increasingly recognised as an important alternative pathway accounting for up to 30% of CRC cases. Endoscopists should be aware of the unique features of serrated lesions so that their early detection, appropriate resection and surveillance interval can be optimised.