Introduction

The role of capsule endoscopy (CE) for the surveillance of small-bowel (SB) cancer in asymptomatic Lynch syndrome (LS) patients has been questioned in recent years, with contradicting results. The overall lifetime risk of SB cancer in this population is around 4-5%, with an age-dependent pattern [1]. Besides, recent data highlight that, depending on the affected path_MMR gene, the frequencies of tumors other than colorectal cancer vary and that affected patients develop subsequent cancers later in life. The aim of this meta-analysis is to evaluate the diagnostic yield (DY) of CE as a screening tool in asymptomatic LS patients.

Aims & Methods

A systematic literature search was conducted in Pubmed, Embase and Web of Science to identify all studies evaluating SB cancer surveillance with CE in asymptomatic LS patients. The primary outcome was the evaluation of the DY of CE in consecutive screening rounds, for both CE-identified pathology and histologically-confirmed pathology (i.e., adenoma or adenocarcinoma). Pooled estimates of DY were calculated from random effects models.

Results

Five studies including 583 patients were identified for data extraction and statistical analysis [2-6] [Table]. The estimated pooled DY for CE-identified pathology was 8% in the first screening round (95% confidence interval [CI] 4-12%) and 6% in the second (95% CI 2-10%). Limiting the analysis to histologically-confirmed pathology, the pooled DY of the second-round screening dropped to 0% (95% CI 0-6%). The time interval between screening rounds was approximately 2 years.
Adenomas were detected in 8 patients (4 males) with a median age of 47.5 years (interquartile range [IQR] 19), while adenocarcinomas were diagnosed in 8 patients (5 males) with a median age of 62.5 years (IQR 17.25). MLH1 was the most involved path_MMR pathogenic variant (9 out of 16 patients), followed by MSH2 and MSH6 (5 and 2 patients, respectively). No adenocarcinomas were detected in MSH6 carriers, as only adenomas were found in 2 patients, with a considerably higher median age than MSH2 and MLH1 adenoma carriers (70.5 years versus 43.5 and 45). No predominance was observed according to the anatomical location (duodenum, n=6; jejunum, n=6; ileum, n=4).

Conclusion

The detection of adenocarcinoma appeared to have a 15-year delay compared to adenomas, supporting a rather slow adenoma to carcinoma transition.
A surveillance strategy starting from the age of 50, with a time interval between procedures lengthened to at least 5 years (instead of 2) could likely be more effective in reducing the burden of advanced disease, both in terms of cost-effectiveness and efficacy. Prospective data may reveal whether a potential SB surveillance might benefit from gene-associated differences in cancer risk, similar to the recent de-escalation of CRC screening recommendations in MSH6 and PMS2 carriers [7].
In conclusion, although the DY of CE is high in detecting SB lesions in LS, the low number of positive examinations eventually resulted in an even lower number of true-positive patients, with a pooled yield proximate to 0%.
The results of this study confirm that SB cancer surveillance with CE with a 2-year interval in asymptomatic LS individuals is not an effective screening strategy.

References

[1] Dominguez-Valentin M, Sampson JR, Seppälä TT, et al. Cancer risks by gene, age, and gender in 6350 carriers of pathogenic mismatch repair variants: findings from the Prospective Lynch Syndrome Database. Genet Med 2020;22:15–25.
[2] Saurin J-C, Pilleul F, Soussan EB, et al. Small-bowel capsule endoscopy diagnoses early and advanced neoplasms in asymptomatic patients with Lynch syndrome. Endoscopy 2010;42:1057–62.
[3] Haanstra JF, Al-Toma A, Dekker E, et al. Prevalence of small-bowel neoplasia in Lynch syndrome assessed by video capsule endoscopy. Gut 2015;64:1578–83.
[4] Haanstra JF, Al-Toma A, Dekker E, et al. Incidence of small bowel neoplasia in Lynch syndrome assessed by video capsule endoscopy. Endosc Int Open 2017;5:E622–E626.
[5] Perrod G, Samaha E, Perez-Cuadrado-Robles E, et al. Effectiveness of a dedicated small bowel neoplasia screening program by capsule endoscopy in Lynch syndrome: 5 years results from a tertiary care center. Ther Adv Gastroenterol 2020;13:1756284820934314.
[6] DeJesse J, Vajravelu RK, Dudzik C, et al. Uptake and outcomes of small intestinal and urinary tract cancer surveillance in Lynch syndrome. World J Clin Oncol 2021;12:1023–36.
[7] Peltomäki P, Nyström M, Mecklin J-P, et al. Lynch syndrome genetics and clinical implications. Gastroenterology 2023 Jan 24;S0016-5085(23)00050-1. doi:10.1053/j.gastro.2022.08.058 [Online ahead of print]

Introduction

CDH1 gene mutations are associated with gastric and breast cancer. The risk of colorectal cancer may be increased in the presence of this mutation, although evidence is scarce.

Aims & Methods

Aims: To assess the presence of high-risk colorectal polyps (polyp with ≥10mm or with high-grade dysplasia, ≥5 adenomas, any serrated polyp ≥10mm or with dysplasia) and colorectal cancer in patients on surveillance program with mutation in CDH1 gene.
Methods: Retrospective study in patients with CDH1 gene mutation followed in a family risk appointment in a tertiary care hospital.

Results

Data from 36 patients with a mean age of 44.22±14.77 years, 20 males, with a mean follow-up of 5.5 years. Twenty-seven patients had family history of gastric cancer and 9 of gastric and breast cancer; twelve patients had never undergone colonoscopy (age ≤ 40 years). Of the 24 patients who had already undergone at least one colonoscopy, 12 (50%) never removed polyps. Only 4 patients had high-risk polyps (age 30, 52, 59 and 77 years) and no patient presented with colorectal cancer during follow-up.

Conclusion

Although this is a small sample, our study revealed a low percentage of patients with hereditary diffuse gastric cancer with high-risk colorectal polyps (and only one patient with a high-risk polyp aged <50 years) and no patients with colorectal cancer, similar to a population without a CDH1 mutation. Further studies with larger sample sizes are needed to clarify the impact of CDH1 mutation on colorectal cancer.

Introduction

Colorectal cancer (CRC) is the 3rd most common cancer worldwide. Approximately 85% of CRC develop on a background of Wnt/β-catenin signalling impairment. Familial adenomatous polyposis (FAP), caused by inherited APC gene mutations (part of the β-catenin destruction complex), is characterized by the development of hundreds to thousands adenomatous polyps. FAP patients have up to 100% risk of developing CRC during their lifetime. The Wnt/β-catenin together with the PI3K/mTOR signalling control the self-renewal and homeostasis of intestinal stem cells and are frequently deregulated in CRC therefore representing attractive targets for chemoprevention and treatment [1], [2]. It has been shown that each pathway may be deregulated by an altered composition of the gut microbiota [3], [4], which plays an important role in the onset, development and progression of CRC thus representing potential target for prevention and potentially biomarkers for the early detection of deranged Wnt/β-catenin-driven lesions [5].

Aims & Methods

The aim of the study was to identify potential targets for the prevention and early detection of CRC in the setting of Wnt/β-catenin disruption.
Transcriptional and translational levels of Wnt/β-catenin and PI3K/mTOR pathways were evaluated by RT-qPCR and immunohistochemical analysis, respectively, in FAP adenomas (n=17 patients) and in sporadic CRC tissues (tumor stages I-III; n=15 patients). In FAP adenomas germline and somatic APC mutations were confirmed by Sanger and Targeted Next Generation Sequencing. The composition of oral, fecal and mucosal-associated microbiota was sequenced by the bacterial 16S rRNA gene. Non-diseased Faecal Immunochemical Testing positive subjects (FIT+; n=17) were included as control group.

Results

We found increased expressions of AXIN2 and cMYC, downstream targets of Wnt/β-catenin, in FAP adenomas. The activation status of PI3K/mTOR was confirmed by an increase of RPS6 gene and pS6R protein expression, indicating that germline and somatic APC mutations of FAP adenomas induce an activation of both pathways. On the other hand, compared to FAP adenomas, a higher expression of AXIN2, cMYC and cytosolic and nuclear β-catenin was found in CRC, while no changes were detected in pS6R, suggesting that the hyperactivation of Wnt/β-catenin in sporadic CRC contributes to the impairment of mTOR signalling. Importantly, we analyzed the microbiome composition in FAP and CRC settings. The oral microbiota of FAP was significantly enriched of Proteobacteria (p<0.01), which decreased in FAP adenomatous mucosal samples compared to FIT+ and CRC. In contrast, Firmicutes showed an opposite trend in FAP patients, with a decrease in the oral composition (p<0.01) and an increase in the adenomatous mucosa (p<0.05). Interestingly, a significant decrease of the CRC-protective phylum Actinobacteria was found in oral and adenomas microbiota of FAP patients compared to FIT+. In contrast, CRC fecal microbiota was enriched of Proteobacteria and a higher abundance of the well-known cancer associated families Fusobacteriaceae, Clostridiaceae and Gemellaceae was found in CRC mucosal samples compared to FIT+.

Conclusion

These findings reveal new insights into the role of Wnt/β-catenin and PI3K/mTOR pathways in influencing the homeostasis of precancerous CRC lesions. Moreover, by defining different microbial signatures in FAP patients, these results will contribute to the enhancement of non-invasive screening tools for the early detection of WNT signalling-driven colorectal cancers.

References

[1] X. Cheng, X. Xu, D. Chen, F. Zhao, and W. Wang, “Therapeutic potential of targeting the Wnt/β-catenin signaling pathway in colorectal cancer,” Biomed. Pharmacother., vol. 110, pp. 473–481, 2019, doi: https://doi.org/10.1016/j.biopha.2018.11.082.
[2] J. Zhang, T. M. Roberts, and R. A. Shivdasani, “Targeting PI3K Signaling as a Therapeutic Approach for Colorectal Cancer,” Gastroenterology, vol. 141, no. 1, pp. 50–61, 2011, doi: https://doi.org/10.1053/j.gastro.2011.05.010.
[3] M. H. Noureldein and A. A. Eid, “Gut microbiota and mTOR signaling: Insight on a new pathophysiological interaction,” Microb. Pathog., vol. 118, no. March 2018, pp. 98–104, 2018, doi: 10.1016/j.micpath.2018.03.021.
[4] O. Silva-García, J. J. Valdez-Alarcón, and V. M. Baizabal-Aguirre, “Wnt/β-catenin signaling as a molecular target by pathogenic bacteria,” Front. Immunol., vol. 10, no. SEP, pp. 1–14, 2019, doi: 10.3389/fimmu.2019.02135.
[5] J. H. Kim, Y. J. Kim, G. M. Oh, W. Jung, and S. J. Park, “How is gut microbiome of patients with familial adenomatous polyposis different from healthy people?,” Medicine (Baltimore)., vol. 101, no. 49, p. e32194, Dec. 2022, doi: 10.1097/MD.0000000000032194.