Peutz-Jeghers syndrome (PJS) is an autosomal dominant disease that is characterized by gastrointestinal hamartomatous polyposis and mucocutaneous melanin spots. The tumor suppressor gene, STK11/LKB1, which is located on chromosome 19p13.3, has been reported to be responsible for this condition. PJS is complicated by benign and malignant tumors of various organs and complications from rare diseases, including sex cord tumor with annular tubules (SCTAT) and minimal deviation adenocarcinoma (MDA), which have also recently attracted attention in the field of gynecology. Among the total MDA cases, 10% are complications of PJS, and mutations in the STK11 gene are closely associated with the development and prognosis of MDA. Furthermore, a new type of uterine cervical tumor, lobular endocervical glandular hyperplasia (LEGH), has been identified and has been predicted to be a precancerous lesion of MDA. The first case of LEGH induced by a germline STK11 mutation has also been described. A high risk of endometrial cancer in PJS has also been reported. These developments suggest that PJS is an important syndrome of hereditary gynecological tumors that requires further study.

Endometrial cancer is the seventh most common cancer worldwide among females. An increased incidence and a younger age of patients are also predicted to occur, and therefore elucidation of the pathological mechanisms is important. However, several aspects of the mechanism of carcinogenesis in the endometrium remain unclear. Associations with genetic mutations of cancer-related genes have been shown, but these do not provide a complete explanation. Therefore, epigenetic mechanisms have been examined. Silencing of genes by DNA hypermethylation, hereditary epimutation of DNA mismatch repair genes and regulation of gene expression by miRNAs may underlie carcinogenesis in endometrial cancer. New therapies include targeting epigenetic changes using histone deacetylase inhibitors. Some cases of endometrial cancer may also be hereditary. Thus, patients with Lynch syndrome which is a hereditary disease, have a higher risk for developing endometrial cancer than the general population. Identification of such disease-related genes may contribute to early detection and prevention of endometrial cancer.

Hereditary gynecological cancers are caused by several inherited genes. Tumors that arise in the female reproductive system, such as ovaries and the uterus, overlap with hereditary cancers. Several hereditary cancer-related genes are important because they might lead to therapeutic targets. Treatment of hereditary cancers should be updated in line with the advent of various new methods of evaluation. Next-generation sequencing has led to rapid, economical genetic analyses that have prompted a concomitant and significant paradigm shift with respect to hereditary cancers. Molecular tumor profiling is an epochal method for determining therapeutic targets. Clinical treatment strategies are now being designed based on biomarkers based on tumor profiling. Furthermore, the National Comprehensive Cancer Network (NCCN) guidelines significantly changed the genetic testing process in 2020 to initially consider multi-gene panel (MGP) evaluation. Here, we reviewed the molecular features and clinical management of hereditary gynecological malignancies, such as hereditary breast and ovarian cancer (HBOC), and Lynch, Li–Fraumeni, Cowden, and Peutz–Jeghers syndromes. We also reviewed cancer-susceptible genes revealed by MGP tests.

In the last few years, PARP inhibitors against Hereditary Breast and Ovarian Cancer (HBOC) and immune checkpoint inhibitors against microsatellite instability (MSI)-high solid tumors have been introduced into clinical practice also in Japan, and treatment for hereditary tumors has been changing significantly. Furthermore, diagnostic tests with Next Generation Sequencing (NGS) which enables cancer genomic medicine have been approved with full coverage under the National Health Insurance recently in Japan. It is clear that cancer treatment in Japan has reached a major turning point. With the development of cancer genomic medicine, germline variants are not found in secondary, but rather have become the first to be identified as therapeutic targets. Henceforth, hereditary tumors will be diagnosed more frequently through cancer genomic medicine in preference to using classical criteria. We have to pay attention to genetic counseling for these patients, because backgrounds are different from classically diagnosed hereditary tumors. In cancer genetics, correct and appropriate evaluation of germline variants is extremely important. In addition, it would be a pivotal role in genetic medicine, to examine the germline reports sufficiently to apply appropriate treatment for patients, and to provide recommended medical management for patient’s family.