Background. Lynch syndrome is the most common genetic predisposition for hereditary cancer. Carriers of pathogenic changes in mismatch repair (MMR) genes have an increased risk of developing colorectal (CRC), endometrial, ovarian, urinary tract, prostate, and other cancers, depending on which gene is malfunctioning. In Lynch syndrome, differences in cancer incidence (penetrance) according to the gene involved have led to the stratification of cancer surveillance. By contrast, any differences in penetrance determined by the type of pathogenic variant remain unknown. Objective. To determine cumulative incidences of cancer in carriers of truncating and missense or aberrant splicing pathogenic variants of the MLH1 and MSH2 genes. Methods. Carriers of pathogenic variants of MLH1 (path_MLH1) and MSH2 (path_MSH2) genes filed in the Prospective Lynch Syndrome Database (PLSD) were categorized as truncating or missense/aberrant splicing according to the InSiGHT criteria for pathogenicity. Results. Among 5199 carriers, 1045 had missense or aberrant splicing variants, and 3930 had truncating variants. Prospective observation years for the two groups were 8205 and 34,141 years, respectively, after which there were no significant differences in incidences for cancer overall or for colorectal cancer or endometrial cancers separately. Conclusion. Truncating and missense or aberrant splicing pathogenic variants were associated with similar average cumulative incidences of cancer in carriers of path MLH1 and path_MSH2.

BACKGROUND: Germline mutations in the DNA polymerase genes POLD1 and POLE confer high risk for multiple colorectal adenomas and colorectal cancer. However, prevalence and the clinical phenotype of mutation carriers are still not fully characterized. OBJECTIVE: The purpose of this study was to assess the prevalence of germline mutations and to describe the genotype-phenotype correlation in POLD1 and POLE genes in Jewish subjects with multiple colorectal adenomas and/or early-onset mismatch repair proficient colorectal cancers. DESIGN: This study is a comparison of genetic and clinical data from affected and control groups. SETTINGS: The study was conducted at a high-volume tertiary referral center. PATIENTS: The study cohort included 132 subjects: 68 with multiple colorectal adenomas and 64 with early-onset mismatch repair proficient colorectal cancers. The control group included 5685 individuals having no colorectal cancer or colorectal adenomas. MAIN OUTCOME MEASURES: Study and control subjects were tested for POLD1 and POLE mutations and a clinical correlation was assessed. RESULTS: Eleven of the 132 study subjects (8.3%) carried either a POLD1 or a POLE mutation: 7 of 68 (10.3%) subjects with multiple colorectal adenomas and 4 of 64 (6.2%) subjects with early-onset mismatch repair proficient colorectal cancer. Three mutations were detected, showing statistical significance in frequency between study and control groups (p < 0.001). Eight of the 11 mutation carriers were Ashkenazi Jews carrying the same POLD1 mutation (V759I), implicating it as a possible low-to-moderate risk founder mutation. Phenotype of mutation carriers was notable for age under 50 at diagnosis, a propensity toward left-sided colorectal cancer, and extracolonic tumors (64%, 100%, and 27% of cases). LIMITATIONS: The study cohort was limited by its relatively small size. CONCLUSIONS: Germline mutations in POLD1 and POLE were found to be relatively frequent in our Jewish cohorts. Further studies are needed to clarify the importance of POLD1 and POLE mutations and to define the most suitable surveillance program for Jewish and other POLD1 and POLE mutation carriers. See Video Abstract at http://links.lww.com/DCR/A658.

Purpose: To survey risk-reducing hysterectomy and bilateral salpingo-oophorectomy (BSO) practice and advice regarding hormone replacement therapy (HRT) in women with Lynch syndrome. Methods: We conducted a survey in 31 contributing centers from the Prospective Lynch Syndrome Database (PLSD), which incorporates 18 countries worldwide. The survey covered local policies for risk-reducing hysterectomy and BSO in Lynch syndrome, the timing when these measures are offered, the involvement of stakeholders and advice regarding HRT. Results: Risk-reducing hysterectomy and BSO are offered to path_MLH1 and path_MSH2 carriers in 20/21 (95%) contributing centers, to path_MSH6 carriers in 19/21 (91%) and to path_PMS2 carriers in 14/21 (67%). Regarding the involvement of stakeholders, there is global agreement (~90%) that risk-reducing surgery should be offered to women, and that this discussion may involve gynecologists, genetic counselors and/or medical geneticists. Prescription of estrogen-only HRT is offered by 15/21 (71%) centers to women of variable age range (35–55 years). Conclusions: Most centers offer risk-reducing gynecological surgery to carriers of path_MLH1, path_MSH2 and path_MSH6 variants but less so for path_PMS2 carriers. There is wide variation in how, when and to whom this is offered. The Manchester International Consensus Group developed recommendations to harmonize clinical practice across centers, but there is a clear need for more research.

INTRODUCTION: Variants in SMAD4 or BMPR1A cause juvenile polyposis syndrome, a rare autosomal dominant condition characterized by multiple gastrointestinal hamartomatous polyps. A phenotype of attenuated adenomatous polyposis without hamartomatous polyps is rare. METHODS: We describe a retrospective cohort of individuals with SMAD4 or BMPR1A heterozygous germline variants, having ≥10 cumulative colorectal adenomas and/or colorectal cancer without hamartomatous polyps. All individuals had multigene panel and duplication/deletion analysis to exclude other genetic syndromes. RESULTS: The study cohort included 8 individuals. The pathogenic potential of the variants was analyzed. Variants detected included 4 missense variants, 1 nonsense variant, 1 splice site variant, and 2 genomic deletions. Features of pathogenicity were present in most variants, and cosegregation of the variant with polyposis or colorectal cancer was obtained in 7 of the 8 families. Three of 8 individuals had colorectal cancer (age less than 50 years) in addition to the polyposis phenotype. Two individuals had extraintestinal neoplasms (pancreas and ampulla of Vater). DISCUSSION: The clinical phenotype of SMAD4 and BMPR1A variants may infrequently extend beyond the classical juvenile polyposis syndrome phenotype. Applying multigene panel analysis of hereditary cancer-related genes in individuals with unexplained polyposis can provide syndrome-based clinical surveillance for carriers and their family members.

Introduction: Abdominal desmoid tumors are locally aggressive tumors that develop in familial adenomatous polyposis (FAP) patients, within the mesentery or abdominal wall. The understanding and implications of the treatment regimens are evolving. Aim: To assess the course, treatment, and outcomes of FAP and non-FAP abdominal desmoids and their related genetic alterations. Methods: Retrospective cohort study. Demographics, tumor characteristics, oncological and surgical history, complications, genetic-testing, and mortality data were retrieved from two tertiary referral centers. Results: Sixty-two patients were identified (46 FAP and 16 non-FAP). Thirty-eight patients (61.3%) underwent surgical procedures (12 urgent and 26 elective). Out of 33 tumor resections, 39.4% recurred. Hormonal therapy, COX-inhibitors, chemotherapy, imatinib, and sorafenib were used in 35 (56.4%), 30 (48.4%), 18 (29.1%), 7 (11.3%), and 8 (12.9%) of patients, respectively, with a 2 year progression-free survival of 67.8%, 57.7%, 38.4%, and 28.5%, respectively. Forty-one patients (66.1%) suffered complications: bowel obstruction (30.6%), hyperalimentation (14.5%), ureteral obstruction (12.9%), perforation (11.3%), abscess formation (3.2%), and spinal cord compression (3.2%). Non-FAP patients carried pathogenic mutations in CHEK2, BLM, ERCC5, MSH6, and PALB2. Conclusions: Abdominal desmoids are mostly FAP-related and are associated with severe outcomes. We also report a group of non-FAP abdominal desmoids, which includes patients with additional cancer-related gene alterations. This interesting group should be further explored.