Background Prophylactic total gastrectomy (PTG) is a risk-reducing strategy considered in individuals at high risk for diffuse gastric cancer (DGC) associated with germline CDH1 pathogenic variants. Methods A systematic literature search (PubMed, Scopus) was conducted to identify studies that performed PTGs in CDH1 carriers. Data were analysed using a random-effects generalised linear mixed model. Cochran's Q test was used to assess the heterogeneity between studies. Forest plots were used to display study-specific estimates, and the pooled estimates were calculated within three subsequent cohort periods (2001-2010; 2011-2020; 2021-2025). Statistical analyses were performed using R software. Results A total of 21 studies were considered out of 302 originally identified, including a total of 967 CDH1 carriers. PTG was performed in 62.9% of CDH1 pathogenic variant carriers. Advanced DGC (>pT1a) was detected in 1.1% and <= pT1a in 79% in postoperative PTG specimens. The majority of PTGs were reported from North America (58.9%). The pooled proportion of PTG decreased from 83.2% (95% CI 61.0% to 94.0%) in 2001-2010 to 71.0% (95% CI 59.0% to 80.7%) in 2011-2020 and to 67.5% (95% CI 48.9% to 81.8%) in 2021-2025 (p for trend=0.12). Conclusion About 60% of PTGs were reported from North America. The majority of the lesions were classified as pT1a. PTG indication has been progressively and constantly decreasing during the last years considered. This can be related to the recent genetic analyses reporting a lower DGC risk in CDH1 carriers and with the improvement in detection of early lesions during endoscopy. PROSPERO registration number CRD420261368873.
Background Mainstreaming, in which genetic testing is shifted outside clinical genetics, can improve access to genetic testing. This is being explored in several countries, including Canada, the USA and the UK. However, standardised practice within a jurisdiction helps ensure equitable high-quality access. This study aimed to evaluate consistency in the implementation of cancer genetics mainstreaming across Ontario, Canada.Methods Adult cancer genetics centres in Ontario were emailed an online survey in June 2025, which was completed by mainstreaming implementation leads. Results were anonymised and analysed in aggregate.Results Of 18 centres contacted, 13 responded; 12/13 reported having implemented cancer genetics mainstreaming. All mainstreaming centres offered pathways for breast, ovarian, prostate and pancreatic cancers, primarily based on personal history criteria. Most centres did not mainstream for other cancer sites but were planning to expand. A 19-gene hereditary breast/ovarian/prostate panel was most commonly ordered. There was variation in the timepoint of genetics service involvement. Turnaround times for expedited results were relatively consistent (median 21 days, IQR 18-22), whereas turnaround times for routine results varied widely (median 50 days, IQR 36-94).Conclusion Across Ontario, centres were generally consistent in mainstreaming the most common indications. Opportunities to improve quality and equity include reducing variability in routine turnaround time, standardising management pathways for negative results and streamlining ordering to align with eligibility criteria. Some centres cited limited genetics knowledge as an implementation barrier, though engagement improved over time. Ongoing evaluation of mainstreaming can support consistent access to care.
