Connection between Breast and Ovarian Cancer: Identified Links and Risk Factors
Breast and ovarian cancers share a strong genetic link, especially in individuals with mutations in the BRCA1 and BRCA2 genes. These genes are vital for DNA repair, and mutations increase the risk of both cancers, often at an earlier age.
Research reveals that breast cancer patients face a heightened risk of developing ovarian cancer, a risk that is even greater if the breast cancer is linked to BRCA1 or BRCA2 mutations. However, this increased risk is primarily due to the mutual genetic factors, not the diseases themselves.
Studies suggest that individuals with breast cancer are approximately twice as likely to develop primary ovarian cancer. Conversely, those with ovarian cancer may have a 1.6-fold increased risk of subsequent breast cancer, although the risk varies based on the time since the initial cancer diagnosis.
Individuals with ovarian cancer also face an increased risk of developing breast cancer, often due to genetic mutations.
Mutations in the BRCA1 and BRCA2 genes are the most significant shared risk factors. Approximately 60% of families with ovarian and breast cancer have BRCA1 gene mutations, while about 20% have BRCA2 mutations.
Apart from these genetic factors, other shared risk factors for breast and ovarian cancers may include:
- A family history of either cancer
- Older age, with ovarian cancer typically occurring in individuals over 40 years, and breast cancer in those ages 55 years or older
- Overweight or obesity
- Having a first child after age 30
- Never having children
- Not breastfeeding
- Hormone therapy after menopause
While some risk factors are unchangeable, people can manage their modifiable risks, such as:
- Achieving and maintaining a moderate weight: This can help reduce the risk of both breast and ovarian cancers. Obesity may cause higher estrogen levels, which can increase the risk of breast cancer.
- Regular exercise: Regular physical activity reduces the risk of breast cancer and may also have direct anticancer effects, although the evidence is limited for ovarian cancer.
- Alcohol: Reducing alcohol intake can help lower the risk of breast cancer; the risk increases with alcohol consumption, so healthcare professionals may recommend limiting intake.
- Oral contraceptives: Oral contraceptives may slightly increase the risk of breast cancer but may decrease the risk of ovarian cancer. Discuss contraception options with a doctor to determine the best choice based on individual circumstances.
Genetic testing for BRCA1, BRCA2, and other relevant mutations is the best strategy for monitoring and prevention in individuals carrying these genetic mutations. For those at high risk, doctors may consider additional options such as prophylactic surgeries to remove organs or tissues to prevent the occurrence or spread of cancer.
A 2020 observational study suggests that people with both primary breast cancer and primary ovarian cancer have a relatively favorable outlook, with 5- and 10-year overall survival rates of around 90%. The outlook is generally more positive when the interval between the two diseases is longer. However, ovarian cancer following breast cancer tends to be diagnosed at a later stage, which can negatively impact survival.
Individuals should speak with a doctor if signs or symptoms of breast or ovarian cancer appear, especially for those with a personal or family history. Those with a history of breast or ovarian cancer should remain vigilant for signs of recurrence or a second cancer, as early detection and prompt treatment are crucial for improving outcomes.
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People with ovarian cancer may have an increased risk of developing bladder, bile duct, colorectal, acute leukemia, or melanoma of the eye. Breast cancer may metastasize (spread) to the ovaries, although it is relatively uncommon, more likely in hormone receptor-positive breast cancers or individuals with BRCA mutations.
High-risk factors for ovarian cancer include BRCA1 or BRCA2 gene mutations, a family history of ovarian, breast, or colorectal cancer, Lynch syndrome, endometriosis, never having been pregnant, having a late first pregnancy, and age over 40 years.
- Individuals with breast cancer, especially those with BRCA1 or BRCA2 mutations, have a heightened risk of developing ovarian cancer.
- The risk of ovarian cancer is higher for those with a family history of either breast or ovarian cancer.
- The risk of both breast and ovarian cancers may also increase with older age, obesity, never having children, not breastfeeding, and hormone therapy after menopause.
- Regular exercise, maintaining a moderate weight, reducing alcohol intake, and discussing contraception options with a doctor can help manage modifiable risks for breast and ovarian cancers.
- Genetic testing for BRCA1, BRCA2, and other relevant mutations is crucial for monitoring and prevention in individuals carrying these genetic mutations.
- People with a history of breast or ovarian cancer should remain vigilant for signs of recurrence or a second cancer, as early detection and prompt treatment are crucial for improving outcomes.
