Understand the Heredity of Ovarian Cancer, And Its International Medical Guidelines

Epithelial Ovarian Cancer
Ovarian cancer is the sixth most common cancer among women in Hong Kong. 1 out of 94 women will develop ovarian cancer in their lifetime. As far as women’s diseases are concerned, the prevalence of ovarian cancer is not as high as that of breast cancer. However, symptoms of ovarian cancer are often overlooked or considered to be merely caused by other diseases, which is a potentially harmful assumption that must be addressed.

Heredity of Ovarian Cancer

The common pathogenic genes of ovarian cancer are BRCA1 and BRCA2, and about 10-15% of ovarian cancers are caused by genetic mutations. The presence of a genetic mutation related to ovarian cancer does not necessitate ovarian cancer. However, the lifetime risk of developing ovarian cancer for those with related genetic mutations is 50 times higher than those without, and there is a 50% chance of this genetic mutation being inherited by the next generation. Those tested with a high genetic risk of ovarian cancer should therefore start ovarian cancer screening tests as soon as possible and in more frequent intervals. This is such that ovarian cancer can be detected at an early stage of onset, which will increase effectiveness of treatment interventions.

Types of Ovarian Cancer

Ovarian cancer can be roughly divided into the following three categories.
Type Characteristics
Epithelial Ovarian Cancer Starts in the epithelial layer of the ovary and is the most common type of ovarian cancer, accounting for about 90% of all ovarian cancers
Germ Cell Ovarian Cancer Occurs in the cells in the ovary responsible for making eggs, and usually develops in women before the age of 30
Sex-cord Stromal Cancer Appears in cells responsible for the production of oestrogen and progesterone; it is a rare type of ovarian cancer which can develop in women of any age

Under What Circumstances Should Genetic Testing for Hereditary Ovarian Cancer Be Taken?

According to expert recommendations from the National Comprehensive Cancer Network (NCCN), if any of the following conditions are met, genetic testing for ovarian cancer is recommended for further risk assessment:

  • Individual from a family with a known BRCA1/2 pathogenic/likely pathogenic variant, including such variants found on research testing;
  • Personal history of breast cancer plus one or more of the following:
    • Diagnosed at younger than or equal to 45 years of age
    • Diagnosed at 46-50 years of age with:
      • An additional breast cancer primary at any age
      • More than or equal to one close blood relative with breast cancer at any age
      • More than or equal to one close blood relative with high-grade (Gleason score above 7) prostate cancer
      • An unknown or limited family history
    • Diagnosed at younger than or equal to 60 years of age with:
      • Triple-negative breast cancer
    • Diagnosed at any age with:
      • More than or equal to one close blood relative with:
        • Breast cancer diagnosed at younger than or equal to 50 years old; or
        • Ovarian carcinoma; or
        • Male breast cancer; or
        • Metastatic prostate cancer; or
        • Pancreatic cancer
      • More than or equal to 2 additional diagnoses of breast cancer at any age in patient and/or in close blood relatives
      • Ashkenazi Jewish ancestry
  • Personal history of ovarian carcinoma
  • Personal history of male breast cancer
  • Personal history of pancreatic cancer
  • Personal history of metastatic prostate cancer
  • Personal history of high-grade prostate cancer (Gleason score over 7) at any age with:
    • More than or equal to one close blood relative with ovarian carcinoma, pancreatic cancer, or metastatic prostate cancer at any age or breast cancer at younger than 50 years of age; or
    • More than or equal to two close blood relatives with breast, or prostate cancer (any grade) at any age; or
    • Ashkenazi Jewish ancestry
  • BRCA1/2 pathogenic/likely pathogenic variant detected by tumor profiling on any tumor type in the absence of germline pathogenic/likely pathogenic variant analysis
  • Regardless of family history, some individuals with an BRCA-related cancer may benefit from genetic testing to determine eligibility for targeted treatment.
  • An individual who does not meet the other criteria but with more than or equal to one first- or second-degree blood relative meeting any of the above criteria. The significant limitations of interpreting test results for an unaffected individual should be discussed.

Is There A Need for Genetic Testing Even After Being Diagnosed with Ovarian Cancer? American Society of Clinical Oncology Suggests All Patients with Epithelial Ovarian Cancer Need BRCA Gene Testing

According to ovarian cancer guidelines issued by the American Society of Clinical Oncology in February 2020, all individuals diagnosed with epithelial ovarian cancer should undergo BRCA1/2 genetic testing, regardless of whether they have a family history of ovarian cancer. The guidelines state that genetic testing for those with ovarian cancer can aid in assembling prognostic information and facilitate better treatment options for the individual. Further analysis of genetic information will also help reveal whether the individual’s family members have the risk of carrying such genetic mutations.

Although many medical societies around the world recommend that women with ovarian cancer undergo genetic testing, only about 30% of women with ovarian cancer do so. It is the hope that the implementation of these medical guidelines will ensure that all patients with ovarian cancer can receive the best possible care, not just for themselves, but also for the sake of their families and future generations.

What should an individual do if in possession of an ovarian cancer gene mutation?

Being a carrier of ovarian-cancer-related gene mutations means that the individual will have a higher risk of developing ovarian cancer than the average person. According to the recommendations of the Cancer Expert Working Group (CEWG) from the Centre for Health Protection of the Department of Health in the Hong Kong Government, women at general risk do not need to be screened if they do not have symptoms of ovarian cancer; on the other hand, women who are at high genetic risk of ovarian cancer should consider seeking additional medical advice to evaluate their course of action regarding possibly developing ovarian cancer, be it a formal diagnosis, further genetic testing, or regular screening needs.

Reference material:

HKSAR Centre for Health Protection. Cancer Expert Working Group on Cancer Prevention and Screening. Recommendations on Prevention and Screening for Ovarian Cancer for Health Professionals. https://www.chp.gov.hk/files/pdf/ovarian_cancer_professional_hp.pdf

Hong Kong Cancer Registry, Hospital Authority: Statistics on ovarian and peritoneal cancer in 2018 https://www3.ha.org.hk/cancereg/pdf/factsheet/2018/ovary_2018.pdf

Konstantinopoulos PA, Lacchetti C, Annunziata CM. Germline and Somatic Tumor Testing in Epithelial Ovarian Cancer: ASCO Guideline Summary. JCO Oncol Pract. 2020 Aug;16(8):e835-e838. doi: 10.1200/JOP.19.00773. Epub 2020 Feb 19. PMID: 32074015. https://ascopubs.org/doi/10.1200/JCO.19.02960

National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guideline in Oncology (NCCN Guidelines®). Genetic/Familial High-Risk Assessment: Breast and Ovarian. Version 3.2019002E

NCCN Guideline for Patients ® Ovarian Cancer, Epithelial Ovarian Cancer 2019. https://www.nccn.org/patients/guidelines/content/PDF/ovarian-patient.pdf#page=15