Racial Differences in Oncogene Mutations Detected in Early-Stage Low-Grade Endometrial Cancers

Objective: To describe the pattern and frequency of oncogene mutations in white and African American women with endometrial cancer and to determine if racial differences in oncogene mutations exist among women with pathologically similar tumors. Methods: Patients with endometrial cancer from a large urban hospital were identified through medical records, and representative formalin-fixed paraffin-embedded tumor blocks were retrieved. The study sample included 150 patients (84 African Americans) who underwent total abdominal hysterectomy for endometrial cancer. The Sequenom MassARRAY system and the OncoCarta Assay version 1.0 (Sequenom) were used to test for 238 mutations in 19 common oncogenes. The chi(2) test and the Fisher exact test were used to assess differences in distribution of variables by race and oncogene mutation status. Results: There were 20 mutations identified in 2 oncogenes (PIK3CA and KRAS) in tumors from 19 women (12.7%). Most of the mutations were found in PIK3CA (16/20). Thirteen percent of endometrioid tumors harbored mutations (11 PIK3CA and 2 KRAS) as did 29% of the malignant mixed Mullerian tumors (3 PIK3CA and 1 KRAS). There were no observed mutations in serous, clear cell, or mucinous tumor types. Among low-grade endometrioid cancers, tumors from African American patients were significantly associated with harboring either a KRAS or PIK3CA mutation (P = 0.04), with 7 PIK3CA mutations and all 4 KRAS mutations identified in African American women. Conclusions: This study provides preliminary evidence that oncogene mutation frequency of some subtypes of histologically similar endometrial carcinoma differ by race. Additional studies are needed to further explore this phenomenon in patients with endometrial carcinoma.