CDH1 Genotype Exploration in Women With Hereditary Lobular Breast Cancer Phenotype.

Importance: Pathogenic or likely pathogenic (P/LP) germline CDH1 variants are associated with risk for diffuse gastric cancer and lobular breast cancer (LBC) in the so-called hereditary diffuse gastric cancer (HDGC) syndrome. However, in some circumstances, LBC can be the first manifestation of this syndrome in the absence of diffuse gastric cancer manifestation. Objectives: To evaluate the frequency of germline CDH1 variants in women with the hereditary LBC (HLBC) phenotype, somatic CDH1 gene inactivation in germline CDH1 variant carriers' tumor samples, and the association of genetic profiles with clinical-pathological data and survival. Design, Setting, and Participants: This single-center, longitudinal, prospective cohort study was conducted from January 1, 1997, to December 31, 2021, with follow-up until January 31, 2023. Women with LBC seen at the European Institute of Oncology were included. Testing for germline CDH1, BRCA1, and BRCA2 genes was performed. Somatic profiling was assessed for germline CDH1 carriers. Main Outcomes and Measures: Accurate estimates of prevalence of germline CDH1 variants among patients with HLBC and the association of somatic sequence alteration with HLBC syndrome. The Kaplan-Meier method and a multivariable Cox proportional hazards regression model were applied for overall and disease-free survival analysis. Results: Of 5429 cases of primary LBC, familial LBC phenotype accounted for 1867 (34.4%). A total of 394 women with LBC were tested, among whom 15 germline CDH1 variants in 15 unrelated families were identified. Among these variants, 6 (40.0%) were P/LP, with an overall frequency of 1.5% (6 of 394). Of the 6 probands with P/LP CDH1 LBC, 5 (83.3%) had a positive family history of BC and only 1 (16.7%) had sporadic juvenile early-onset LBC. No germline BRCA1 and BRCA2 variants were identified in CDH1 carriers. An inactivating CDH1 mechanism (second hit) was identified in 4 of 6 explored matched tumor samples (66.7%) in P/LP germline carriers. The P/LP CDH1 LBC variant carriers had a significantly lower age at diagnosis compared with the group carrying CDH1 variants of unknown significance or likely benign (42.5 [IQR, 38.3-43.0] vs 51.0 [IQR, 45.0-53.0] years; P = .03). Conclusions and Relevance: In this cohort study, P/LP germline CDH1 variants were identified in individuals not fulfilling the classic clinical criteria for HDGC screening, suggesting that identification of these variants may provide a novel method to test women with LBC with early age at diagnosis and/or positive family history of BC.

Clinical Implication of CDH1 Mutations in Genetic Testing for Diffuse Gastric Cancer Patients.

INTRODUCTION: The objective of this study was to reclassify published germline CDH1 variants identified in gastric cancer (GC) in accordance with the latest ClinVar definition and to correlate their pathogenicity with the established international clinical criteria for genetic testing. METHODS: The relevant literature dating from 1998 to 2019 was systematically searched for data on CDH1 germline mutations in accord with PRISMA guidelines. The collected variants were classified according to the latest ClinVar definition into the following classes: benign (B), likely benign (LB), pathogenic (P), likely pathogenic (LP), and variant of unknown significance (VUS). The McNemar test was used to compare the adequacy of current versus previous International GC Linkage Consortium (IGCLC) criteria. RESULTS: We reclassified a total of 247 CDH1 variants, and we identified that about 70% of B/LB variant carriers were not fulfilling the defined clinical criteria. Instead, all P/LP variants (100%) were associated with the hereditary diffuse gastric cancer (HDGC) phenotype fulfilling the 2020 ILGCC criteria, with a significant improvement (p = 0.025) compared to previous version. CONCLUSIONS: We conclude that germline CDH1 genetic testing is indicated only in families meeting the clinical criteria for the HDGC syndrome. This observation suggests that clinical phenotypes that do not clearly fulfill these criteria should not be considered for CDH1 genetic testing.

Global distribution of prophylactic total gastrectomy in E-cadherin (CDH1) mutations.

Individuals with germline E-cadherin (CDH1) mutations are at high risk of developing diffuse gastric cancer (GC) and prophylactic total gastrectomy (PTG) represents the only life-saving treatment. We reviewed all PTGs reported in literature associated with CDH1 germline mutations. A total of 224 PTGs were reported. The majority were described in the United States of America (50%), the Netherlands (17.8%), and Canada (12.5%). GC was identified in 85.4% of cases after PTG, with a high rate of "no cancer" at histopathology identified in the United States of America (19.6%). Considering the mutation type, a total of 61 different germline mutations was reported, primarily non-missense versus missense alterations (86.9% v 13.1%). Twenty-one PTGs were performed in individuals with no family history of GC, and tumor was detected in 33.3% of investigated cases; regarding individuals with a family history of GC, tumor was identified in 85% of cases. PTG remains the best treatment for individuals harboring germline CDH1 mutations and fulfilling specific clinical criteria; in other CDH1-associated conditions, PTG should be suggested, but not strongly recommended. Additional studies are required to assess the cancer risk in those conditions.

CDH1 germline mutations in healthy individuals from families with the hereditary diffuse gastric cancer syndrome.

The objective of this study was to determining the frequency of different sub-types of pathogenic CDH1 germline mutations in healthy and asymptomatic individuals from families with the hereditary diffuse gastric cancer (HDGC) syndrome. Relevant literature dating from 1998 to 2019 was systematically searched for data on CDH1 germline mutations. The collected variants were classified according to their subtype into the following classes: missense, non-sense, splicing, insertions and deletions. The χ2 test was used to estimate if the difference observed between patients with gastric cancer (GC) and unaffected individuals was statistically significant. CDH1 genetic screening data were retrieved for 224 patients with GC and 289 healthy individuals. Among the subjects that had tested CDH1 positive, splicing mutations were found in 30.4% of the healthy individuals and in 15.2% of the patients with GC (p=0.0076). Missense mutations were also found to occur in healthy subjects with higher frequency (22.2%) than in GC-affected individuals (18.3%), but the difference was not significant in this case. In families meeting the clinical criteria for the HDGC syndrome, CDH1 splicing and missense germline mutations have been reported to occur with higher frequency in healthy subjects than in patients with cancer. This preliminary observation suggests that not all pathogenic CDH1 germline mutations confer the same risk of developing GC.

Prognostic value of human papillomavirus in anal squamous cell carcinoma.

PURPOSE: Anal cancer is an uncommon malignancy, but its incidence is increasing worldwide. Chemoradiation is the standard primary treatment for patients with loco-regional limited disease. However, once patients develop metastatic spread, the prognosis is very poor. Human papillomavirus (HPV) is present in around 80 % of anal cancers, but its prognostic and/or predictive value is essentially unknown in this disease. METHODS: We retrospectively evaluated 50 patients with the diagnosis of anal squamous cell carcinoma treated at our institution with combined chemoradiotherapy for loco-regional limited disease. HPV status was evaluated from paraffin-embedded tumor tissues collected at the time of diagnosis by a polymerase chain reaction analysis. RESULTS: Among 50 patients, 42 (84 %) were HPV-positive. Thirty-two (64 %) patients were positive to genotype 16, two (4 %) to genotype 18, and three (6 %) to both 16 and 18. Lymph nodal involvement and clinical stage at diagnosis were more advanced for HPV-positive patients. After a median follow-up of 4 years (range 0.4-13.8), 46 (92 %) patients were alive. Overall, eight patients relapsed: One regional, one loco-regional, and six distant recurrences were observed. Four patients died of metastatic disease. Five-year disease-free survival (DFS) in HPV-positive and HPV-negative patients was 92.5 and 50.0 %, respectively (P < 0.01). In multivariate analysis, HPV-positivity was associated with a statistically significant better 5-year DFS (HR HPV+ vs HPV- 0.10; 95 % CI 0.02-0.50). Five-year overall survival in HPV-positive and HPV-negative patients was 93.3 and 66.7 %, respectively (P = 0.12). CONCLUSIONS: In our study, HPV-positive anal cancers had a statistically significant improved DFS compared to HPV-negative group.