Risk of first onset of colorectal cancer associated with alcohol consumption in Lynch syndrome: a multicenter cohort study

Modifiable Risk Factors and Risk of Colorectal and Endometrial Cancers in Lynch Syndrome: A Systematic Review and Meta-Analysis

PURPOSE

Lynch syndrome is the most common hereditary cause of colorectal and endometrial cancers. Modifiable risk factors, including obesity, physical activity, alcohol intake, and smoking, are well-established in sporadic cancers but are less studied in Lynch syndrome.

METHODS

Searches were conducted on MEDLINE, Embase, and Web of Science for cohort studies that investigated the association between modifiable risk factors and the risk of colorectal or endometrial cancer in people with Lynch syndrome. Adjusted hazard ratios (HRs) and 95% CIs for colorectal and endometrial cancers were pooled using a random effects model. The protocol was prospectively registered on PROSPERO (CRD 42022378462), and the meta-analysis was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-Analysis of Observational Studies in Epidemiology reporting guidelines.

RESULTS

A total of 770 citations were reviewed. Eighteen studies were identified for qualitative synthesis, with seven colorectal cancer (CRC) studies eligible for meta-analysis. Obesity (HR, 2.38 [95% CI, 1.52 to 3.73]) was associated with increased CRC risk. There was no increased CRC risk associated with smoking (HR, 1.04 [95% CI, 0.82 to 1.32]) or alcohol intake (HR, 1.32 [95% CI, 0.97 to 1.81]). Type 2 diabetes mellitus (T2DM) and some dietary factors might increase risk of CRC although more studies are needed. In a qualitative synthesis of three endometrial cancer cohort studies, female hormonal risk factors and T2DM may affect the risk of endometrial cancer, but obesity was not associated with an increased risk.

CONCLUSION

Lifestyle recommendations related to weight and physical activity may also be relevant to cancer prevention for individuals with Lynch syndrome. Further high-quality prospective cohort studies, in particular, including endometrial cancer as an end point, are needed to inform evidence-based cancer prevention strategies in this high-risk population.

A Japanese case of ovarian mucinous adenocarcinoma with germline double variants of MSH2 and BRCA2

Germline double heterozygosity (GDH) is rarely reported in cases of inherited cancer syndromes, and GDH of a mismatch repair gene and BRCA has never been reported in Japan. Nonetheless, the current report demonstrates a case of ovarian mucinous adenocarcinoma with initiated Lynch syndrome (LS)-related surveillance because of a known germline MSH2 variant. Six and a half years after oophorectomy, multiple tumors developed in the patient's lungs, bones, and lymph nodes, and histology results confirmed mucinous adenocarcinoma. Systemic chemotherapy including an anti-PD-L1 antibody was effective for >1 year, but brain metastases developed. Pathology of the brain tumors showed mucinous adenocarcinoma without expression of MSH2 and MSH6, while multi-gene panel testing demonstrated not only high microsatellite instability and a high tumor mutation burden, but also germline BRCA2 variants. Further, germline testing in relatives confirmed both variants were from the paternal line, from which many LS-related cancers develop, but not BRCA-related cancer.

Acetaldehyde and defective mismatch repair increase colonic tumours in a Lynch syndrome model with Aldh1b1 inactivation

ALDH1B1 expressed in the intestinal epithelium metabolises acetaldehyde to acetate, protecting against acetaldehyde-induced DNA damage. MSH2 is a key component of the DNA mismatch repair (MMR) pathway involved in Lynch syndrome (LS)-associated colorectal cancers. Here, we show that defective MMR (dMMR) interacts with acetaldehyde, in a gene/environment interaction, enhancing dMMR-driven colonic tumour formation in a LS murine model of Msh2 conditional inactivation (Lgr5-CreER; Msh2flox/-, or Msh2-LS) combined with Aldh1b1 inactivation. Conditional (Aldh1b1flox/flox) or constitutive (Aldh1b1-/-) Aldh1b1 knockout alleles combined with the conditional Msh2flox/- intestinal knockout mouse model of LS (Msh2-LS) received either ethanol, which is metabolised to acetaldehyde, or water. We demonstrated that 41.7% of ethanol-treated Aldh1b1flox/flox Msh2-LS mice and 66.7% of Aldh1b1-/- Msh2-LS mice developed colonic epithelial hyperproliferation and adenoma formation, in 4.5 and 6 months, respectively, significantly greater than 0% in water-treated control mice. Significantly higher numbers of dMMR colonic crypt foci precursors and increased plasma acetaldehyde levels were observed in ethanol-treated Aldh1b1flox/flox Msh2-LS and Aldh1b1-/- Msh2-LS mice compared with those in water-treated controls. Hence, ALDH1B1 loss increases acetaldehyde levels and DNA damage that interacts with dMMR to accelerate colonic, but not small intestinal, tumour formation.

Lifestyle Behavior Interventions for Preventing Cancer in Adults with Inherited Cancer Syndromes: Systematic Review

(1) Background: The link between lifestyle behaviors and cancer risk is well established, which is important for people with personal/family history or genetic susceptibility. Genetic testing is not sufficient motivation to prompt healthier lifestyle behaviors. This systematic review aims to describe and assess interventions for promoting healthy behaviors in people at high risk of cancer. (2) Methods: The review was performed according to PRISMA guidelines using search terms related to hereditary cancer and health education to identify studies indexed in: CINAHL, MEDLINE, PubMed, Cochrane Library, Scopus, and Joanna Briggs, and published from January 2010 to July 2022. (3) Results: The search yielded 1558 initial records; four randomized controlled trials were eligible. Three included patients with and without a personal history of cancer who were at increased risk of cancer due to inherited cancer syndromes, and one included people undergoing genetic testing due to family history. Interventions targeted diet, physical activity, and alcohol. (4) Conclusions: There is a paucity of research on interventions for promoting healthy lifestyle behaviors in people with a high risk of cancer. Interventions produced positive short-term results, but there was no evidence that behavioral modifications were sustained over time. All healthcare professionals can actively promote healthy behaviors that may prevent cancer.