Connection between Breast and Ovarian Cancer: Causes and Risk Factors
Established Links between Breast and Ovarian Cancer
A growing body of research indicates a strong connection between breast cancer and ovarian cancer, primarily due to shared genetic factors. This association is particularly significant for individuals harboring mutations in the BRCA1 and BRCA2 genes.
The close relationship between these two types of cancer is underpinned by several concurrent genetic risk factors. People possessing these risk factors may face an increased risk for both breast and ovarian cancers.
Additionally, older age, being overweight or obese, and never carrying a pregnancy to term are other common shared risk factors. Some of these factors, such as maintaining a moderate weight, are potentially modifiable.
Individuals who have had breast cancer may experience an increased risk of developing ovarian cancer, especially if their breast cancer originates from genetic mutations such as BRCA1 or BRCA2. Research suggests that these individuals are approximately twice as likely to develop subsequent primary ovarian cancer. In a similar vein, people with ovarian cancer may face a 1.6-fold increased risk of subsequent breast cancer, though this risk fluctuates over time since the initial diagnosis.
Mutations in the BRCA1 and BRCA2 genes are the most significant shared genetic risk factors. Approximately 5-10% of families with ovarian and breast cancer carry BRCA1 gene mutations, while about 20% carry BRCA2 mutations[1][4].
Other shared risk factors for breast and ovarian cancers may include:
- Family history of either cancer
- Older age (with ovarian cancer typically occurring in people over 40 years, and breast cancer in those ages 55 years or older)
- Overweight or obesity
- Having a first child after the age of 30
- Never having children
- Not breastfeeding
- Hormone therapy after menopause
For those at higher risk, management of unchangeable risk factors may involve careful monitoring, lifestyle modifications, and preventive medical procedures. People who have a history of breast or ovarian cancer should discuss more frequent and thorough screenings, potentially including regular mammograms, breast MRI scans, pelvic exams, transvaginal ultrasounds, and CA-125 blood tests with their healthcare professionals[1]. Genetic testing for BRCA1, BRCA2, and other relevant mutations plays a crucial role in monitoring and prevention. In some cases, prophylactic surgeries may be considered to remove organs or tissues and prevent the occurrence or spread of cancer.
Modifiable risk factors, such as achieving and maintaining a moderate weight, regular exercise, reducing alcohol intake, and discussing contraception options with a doctor can help reduce the risk of breast and ovarian cancer.
A 2020 observational study suggests that individuals diagnosed with both primary breast cancer and primary ovarian cancer have relatively favorable overall survival rates, with 5- and 10-year rates of around 90%[1]. The outlook is generally more positive when the interval between the two cancers is longer. However, ovarian cancer diagnosis following breast cancer often occurs at a later stage, which can negatively impact survival. Factors such as a person's age during their first cancer diagnosis and the time between the two cancers can have a significant impact on overall survival[1].
Those who suspect signs or symptoms of breast or ovarian cancer, particularly with a personal or family history of these diseases, should consult with their doctor. Early detection and prompt treatment are critical for improving outcomes.
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Individuals at high risk of ovarian cancer may include those who have BRCA1 or BRCA2 gene mutations, a family history of ovarian, breast, or colorectal cancer, Lynch syndrome, endometriosis, never been pregnant, had a late first pregnancy, or are over the age of 40[2]. Breast cancer can also metastasize to the ovaries in some cases, particularly in breast cancers that are hormone receptor-positive or in individuals with BRCA mutations.
In summary, shared genetic mutations (especially BRCA1 and BRCA2) and similar hormonal and lifestyle factors create a significant shared risk profile for both breast and ovarian cancers. Genetic counseling and testing are often recommended for women with family histories of these cancers to inform risk management and early detection strategies[1][4].
[1] Sieh-Hoeller, E., et. al., Risk of second cancer after breast cancer diagnosis: a systematic review and meta-analysis. BMJ, 2020. 369: m154.[2] National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Ovarian Cancer, Version 3.2021. November 2020. Accessed January 12, 2022.[3] National Cancer Institute. Ovarian Cancer Screening. September 15, 2021. Accessed January 12, 2022.[4] National Cancer Institute. BRCA1 and BRCA2: Cancer Risk and Genetic Testing. December 2, 2021. Accessed January 12, 2022.
- The link between breast cancer and ovarian cancer is primarily due to shared genetic factors, such as mutations in the BRCA1 and BRCA2 genes.
- A family history of breast or ovarian cancer, older age, and being overweight or obese are common shared risk factors for both types of cancer.
- People with a history of breast cancer may have an increased risk of developing ovarian cancer, particularly if their breast cancer originated from genetic mutations like BRCA1 or BRCA2.
- For those at higher risk, management may involve regular screening, lifestyle modifications, genetic testing, and in some cases, prophylactic surgeries.
- Modifiable risk factors, like maintaining a moderate weight and regular exercise, can help lower the risk of breast and ovarian cancer.
- Early detection and prompt treatment are crucial for improving outcomes in cases of breast and ovarian cancer, especially for those with personal or family histories of these diseases.
