Cancer risk and genotype-phenotype correlation in Japanese patients with Cowden syndrome

Cowden syndrome (CS) is an autosomal-dominant hereditary disorder caused by a germline PTEN variant and characterized by multiple hamartomas and a high risk of cancers. However, no detailed data on CS in Asian patients nor genotype-phenotype correlation have been reported.

We performed the first Japanese nationwide questionnaire survey on CS and obtained questionnaire response data on 49 CS patients.

Patients included 26 females (median age 48 years). The incidence of breast, thyroid, endometrium, and colorectal cancer was 32.7%, 12.2%, 19.2% (among females), and 6.1%, respectively. The incidence of any cancers was relatively high among all patients (46.9%, 23/49), and particularly female patients (73.1%, 19/26), compared with previous reports from Western countries. Gastrointestinal (GI) polyps were more frequently found throughout the GI tract compared with previous studies. PTEN variants were detected in 95.6% (22/23) of patients; 12 in the N-terminal region (11 in phosphatase domain) and 10 in the C-terminal (C2 domain) region. The incidence of cancer in the C2 domain group was significantly higher than in the N-terminal region (phosphatase) group. All female patients with C2 domain variant had breast cancer.

Our data suggest that Japanese patients with CS, particularly female patients and patients with C2 domain variant may have a high risk of cancers.