Approach to Lynch Syndrome for the Gastroenterologist

Aspirin and Cancer Survival: An Analysis of Molecular Mechanisms

The benefit of aspirin on cancer survival is debated. Data from randomized clinical trials and cohort studies are discordant, although a meta-analysis shows a clear survival advantage when aspirin is added to the standard of care. However, the mechanism by which aspirin improves cancer survival is not clear. A PubMed search was carried out to identify articles reporting genes and pathways that are associated with aspirin and cancer survival. Gene ontology and pathway enrichment analysis was carried out using web-based tools. Gene-gene and protein-protein interactions were evaluated. Crosstalk between pathways was identified and plotted. Forty-one genes were identified and classified into primary genes (PTGS2 and PTGES2), genes regulating cellular proliferation, interleukin and cytokine genes, and DNA repair genes. The network analysis showed a rich gene-gene and protein-protein interaction between these genes and proteins. Pathway enrichment showed the interleukin and cellular transduction pathways as the main pathways involved in aspirin-related survival, in addition to DNA repair, autophagy, extracellular matrix, and apoptosis pathways. Crosstalk of PTGS2 with EGFR, JAK/AKT, TP53, interleukin/TNFα/NFκB, GSK3B/BRCA/PARP, CXCR/MUC1, and WNT/CTNNB pathways was identified. The results of the present study demonstrate that aspirin improves cancer survival by the interplay of 41 genes through a complex mechanism. PTGS2 is the primary target of aspirin and impacts cancer survival through six primary pathways: the interleukin pathway, extracellular matrix pathway, signal transduction pathway, apoptosis pathway, autophagy pathway, and DNA repair pathway.

Survival outcomes associated with Lynch syndrome colorectal cancer and metachronous rate after subtotal/total versus segmental colectomy: Meta-analysis

BACKGROUND

Lynch syndrome is associated with the most common form of heritable bowel cancer. There remains limited level 1 evidence on survival outcomes and rate of metachronous tumor associated with Lynch syndrome colorectal cancer.

METHODS

A systematic literature search of original studies was performed on Ovid searching MEDLINE, Embase, Cochrane Database of Systematic Reviews, American College of Physicians ACP Journal Club, Database of Abstracts of Reviews of Effects DARE, and Clinical Trials databases from inception of database to February 2021. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guideline was followed. The data were pooled using a random-effects model. All of the P values were 2-tailed, and statistical analysis was performed using RevMan v. 5.3 Cochrane Collaboration.

RESULTS

From 1,942 studies, 15 studies met the inclusion criteria and were included for qualitative and quantitative synthesis. The five-year overall survival was 89.5% (82.0-94.1%), P < .01; I² = 89%. The ten-year overall survival was 80.5% (68.7-88.6%), P < .01; I² = 81%. The fifteen-year overall survival was 70% (33.7%-91.5%), P < .01; I² = 93%. Univariate meta-regression analysis showed no statistically significant difference in 5-year overall survival by sex, age, MLH1, MSH2, MSH6, nor tumor location (right versus left colon). The metachronous tumor rate was 12% to 33% with a follow-up period of up to 15 years, significantly lower in patients who underwent subtotal/total colectomy (0-6%).

CONCLUSION

The overall survival of patients with colorectal cancer with Lynch syndrome was approximately 90% at 5 years, 80% at 10 years, and 70% at 15 years. The metachronous tumor rate was approximately 10% to 30% at up to 15 years, significantly improved by subtotal/total colectomy.

Prognostic and Predictive Values of Mismatch Repair Deficiency in Non-Metastatic Colorectal Cancer

Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide. Universal MMR/MSI testing is standard of care for all patients with newly diagnosed CRC based on multi-society guidelines in the United States. Such testing is intended to identify patients with Lynch Syndrome due to a germline mutation in an MMR gene, but also detects those with sporadic dMMR/MSI-high CRCs. The prognostic utility of MMR/MSI status in non-metastatic colorectal cancer has been studied extensively, yet more limited data are available for its predictive utility. Results have not been entirely consistent due to potential stage-related differences and limited numbers of dMMR/MSI-H patients included in the studies. In this review, we summarize the current evidence for the prognostic and predictive value of dMMR/MSI-H in non-metastatic CRC, and discuss the use of this biomarker for patient management and treatment decisions in clinical practice.

Analysis of metachronous colorectal neoplasms and survival following segmental or extended resection in patients with hereditary non-polyposis colorectal cancer

PURPOSE

The high incidence of metachronous colorectal tumours in patients with hereditary non-polyposis colorectal cancer (HNPCC) encourages extended resection (ER); however, the optimal surgical approach remains unclear. We evaluated the incidences of metachronous colorectal neoplasms following curative colorectal cancer segmental resection (SR) vs ER in patients with HNPCC and investigated patients' oncologic outcomes according to surgical modality and mismatch repair status.

METHODS

We retrospectively investigated medical records of patients with HNPCC (per the Amsterdam II criteria) treated for primary colon cancer at our institution between 2001 and 2017. All patients underwent intensive endoscopic surveillance.

RESULTS

We included 87 patients (36 who underwent SR and 51 who underwent ER). The cumulative incidence of metachronous adenoma was higher in the SR group. One patient in the SR group (2.8%) and 3 in the ER group (5.9%) developed metachronous colon cancer; the difference was not significant (P = 0.693). Four patients in the SR group (11.1%) and 1 in the ER group (2.0%) developed distant recurrences; again, the difference was not significant (P = 0.155). Moreover, no significant differences were observed in the 5-year overall survival rates of patients in the SR and ER groups (88.2% vs 95.5%, P = 0.446); the same was true for 5-year disease-free survival rates (79.5% vs 91.0%, P = 0.147).

CONCLUSION

The incidence of metachronous cancer was not significantly different between the ER and SR groups; however, that of cumulative metachronous adenoma was higher in the SR group. Hence, intensive surveillance colonoscopy may be sufficient for patients with HNPCC after non-extensive colon resection.