Premalignant Colorectal Adenoma Detection in Individuals with Inherited CDH1 Genetic Mutations: A Single-Institution
Adrienne B Shannon1, Christine Laronga2, Caitlyn Balsay-Patel2
1From the Department of Gastrointestinal Oncology.
Objectives:
Pathogenic germline CDH1 variants result in increased risk of gastric (GC) and invasive lobular (ILC) carcinomas with high penetrance. Limited data suggest a higher incidence of colorectal neoplasia in carriers of CDH1 mutations, but data remain limited on the risk of colorectal adenoma formation and the role of colonoscopy in this population.
Methods:
Adult patients who underwent germline testing revealing a pathogenic mutation (PM) or variant of uncertain significance (VUS) in CDH1 were identified and seen in consultation were identified. Clinical and treatment characteristics were analyzed.
Results:
Thirty-eight patients with CDH1 PM or VUS were identified at a single high-volume cancer center. Median age of CDH1 mutational analysis was 42 years (interquartile range 35-58). The majority of patients had deletion (N = 15, 39.5%) or nonsense (N = 6, 15.8%) mutations or VUS (N = 7, 18.4%). Twenty-six (68%), 20 (53%), and 11 (29%) had a family history of ILC, GC, and colon cancer, respectively. Eighteen (47%) patients underwent screening colonoscopy in addition to screening for GC and ILC; the median age at screening colonoscopy was 51.5 years (interquartile range 46-58) and 4 patients (22%) patients were younger than 45 years of age at the time of colonoscopy. Among patients younger than 45 years of age, the rate of adenoma detection was 50% (n = 2/4). Adenomas were identified in 8 (44.4%) patients, and of these patients, 6 (75%) had right-sided, 4 (50%) had left-sided, and 2 (25%) had both right- and left-sided adenomas. No patients were identified on colonoscopy to have colorectal cancers. When examining only patients with CDH1 PM (N = 31), 16 (51.6%) patients underwent screening colonoscopy, and 8 (50%) patients had adenomas detected. Conversely, of the two of the seven CDH1 VUS patients who underwent screening colonoscopy, neither patient had adenomas detected.
Conclusions:
The association between inherited CDH1 variants and colorectal neoplasia remains undefined, but the rate of colorectal adenoma detection in this population of patients is significantly higher than that of the general population. Since these individuals already undergo upper endoscopy for their care, consideration of earlier colonoscopy and insurance approval may be warranted.
