Plasma cell free DNA can discriminate ovarian cancer from benign endometriotic cysts by detecting PIK3CA mutation faintly existing in plasma.

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K18670
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 56040:Obstetrics and gynecology-related
• Research Institution: Osaka University
• Principal Investigator: Yoshimura Akihiko 大阪大学, 医学系研究科, 招へい教員 (10823528)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: cfDNA / 卵巣癌 / PIK3CA / Digital PCR / liquid biopsy

Outline of Final Research Achievements

The differential diagnosis of endometriosis-related cancers and endometriotic cysts is sometimes difficult in clinic. The aim of this study is to pursue its potential as a biomarker to detect ovarian cancer using patients’ plasma. Twenty-seven plasma samples from patients with endometriosis-related cancers were collected. As non-malignant controls, 51 samples were collected from patients with benign endometriotic cysts. The presence of PIK3CA mutation in cell free DNA (cfDNA) existing in patients’ plasma was confirmed with digital PCR method. There were 17 cases of clear cell carcinoma and 10 endometrioid carcinoma. Among 27 patients with endometriosis-related cancers, PIK3CA mutations in plasma were detected in 7 cases (26%) (clear cell carcinoma 5/17 and endometrioid carcinoma 2/10), while any mutations were not detected in plasma of patients with benign endometriotic cysts. This data suggests the potential of ctDNAs as a non-invasive biomarker for ovarian cancer.

Free Research Field

婦人科腫瘍

Academic Significance and Societal Importance of the Research Achievements

子宮内膜症は約10％の有月経女性に発生する疾患でCommon Disease である。その約 0.7 % が将来的に癌化するが、現時点では臨床上有用なバイオマーカーが存在しない。子宮内膜症および関連癌患者におけるDigital PCR 法による血漿中のPIK3CAの H1047R変異同定は、感度こそ27％と低かったが、特異度は75％と高く、陽性適中率は100％であった。癌遺伝子の変異のHot spotを組み合わせることにより、感度の向上は可能であり、Digital PCR 法による血漿中の癌遺伝子変異同定は卵巣癌診療における新たなLiquid Biopsy法として有用である可能性が示唆された。