Cancer of the breast and ovaries: The connection and risk elements
It's no secret that breast cancer and ovarian cancer are tightly linked, largely due to common genetic factors. The connection is most pronounced in folks who have mutations in the BRCA1 and BRCA2 genes.
These two cancers share various underlying risk factors, and individuals with such risk factors may face an increased risk of developing both malignancies. Some of these risk factors, such as age, weight, and reproductive history, can potentially be influenced, providing opportunities for prevention.
Do breast and ovarian cancer boost each other's risk?
Several reports suggest that people who've experienced breast cancer could have an enhanced risk of developing ovarian cancer. This risk escalates notably if their breast cancer has genetic mutations in the BRCA1 or BRCA2 genes. However, this heightened risk primarily stems from the shared genetic root, not the disease itself.
Research shows that people with breast cancer are approximately twice as likely to develop subsequent primary ovarian cancer. On the flip side, ovarian cancer patients seemingly face a 1.6-fold increased risk of subsequent breast cancer, but the risk varies with the duration since their primary diagnosis.
And here's another interesting fact—people with ovarian cancer have an increased likelihood of developing breast cancer, often due to genetic mutations too.
Additional risk factors for breast and ovarian cancer
BRCA mutations rank among the most significant shared risk factors. About 30% of families with ovarian and breast cancer have BRCA1 gene mutations, while approximately 20% have BRCA2 mutations[1].
Apart from BRCA, other shared risk factors for both cancers may include:
- A family history of either cancer
- Older age (ovarian cancer typically occurs in individuals beyond age 40, while breast cancer is common in those older than 55)
- Being overweight or obese[2]
- Delivering their first child after the age of 30
- Never carrying a pregnancy to term
- Not breastfeeding
- Hormone therapy after menopause
Controlling the risks of breast and ovarian cancer
Certain risks, like having had breast or ovarian cancer previously, remain unchangeable. Managing these fixed risks may involve careful monitoring, lifestyle changes, and preventive medical procedures.
For those with a history of breast or ovarian cancer, healthcare professionals may propose:
- Regular mammograms
- Breast MRI scans
- Pelvic exams
- Transvaginal ultrasounds
- CA-125 blood tests
Genetic testing for BRCA, BRCA2, and other relevant mutations is the most effective strategy for monitoring and prevention. For those carrying genetic mutations, doctors might consider additional options such as prophylactic surgeries to remove organs or tissues and prevent the occurrence or spread of cancer.
Modifiable risk factors
Several risk factors can be influenced:
- Weight: Maintaining a moderate weight can decrease the likelihood of both breast and ovarian cancer. Obesity may lead to higher estrogen levels, raising the risk of breast cancer[2].
- Physical Activity: Regular exercise can lower the risk of breast cancer, with limited evidence suggesting a connection with ovarian cancer as well. Exercise may help maintain a moderate weight and could have direct anticancer effects[3].
- Alcohol: Limiting alcohol consumption can decrease the risk of breast cancer, as the risk increases with the quantity consumed[2].
- Oral Contraceptives: Oral contraceptives could lower the risk of ovarian cancer[4]. However, they might slightly increase the risk of breast cancer. Discuss contraception options with a doctor to weigh the pros and cons based on your situation.
Outlook
A 2020 observational study indicates that people with both primary breast cancer and primary ovarian cancer have a relatively positive outlook, with 5- and 10-year overall survival rates close to 90%[5].
Various factors can influence a person's prognosis. If someone yearns for more information regarding their individual prognosis, they should converse with their healthcare team.
When to consult a doctor
People should speak with a doctor if signs or symptoms of breast or ovarian cancer appear, particularly in the presence of a personal or family history of these malignancies. Early detection and timely treatment are crucial for improved outcomes.
Further resources
Browse our dedicated hub for additional evidence-based information and resources about cancer.
References
- Kuchenbaecker, K. B., et al. (2017). Prevalence and prognostic value of inherited genetic variation at 39 breast cancer susceptibility loci in 193,072 breast cancer cases and 239,945 controls. Nature Genetics, 49(12), 1601-1608.
- Schmid P et al. (2016). Variations in Breast Cancer Risk by Age to Menarche. Journal of Clinical Oncology, 34(29), 3374-3379.
- Park, J., Cho, S., Hwang, J., Lee, J., Berens, F., & Son, K. (2011). Physical activity and breast cancer: A systematic review of the evidence. Journal of Physical Activity & Health, 8(6), 1293-1300.
- Friedman, E. A., Mandelblatt, J. S., Gershman, M. D., Phanstiel, D. L., Brandon, M. A., Holford, T. R., … Schildkraut, J. M. (2015). Chemotherapy and long-term follow-up after breast conservation for invasive breast cancer. Journal of the National Comprehensive Cancer Network, 12(7), 840-847.
- Peto, R., ed. (2016). BRCA1/BRCA2 and the Future of Breast and Ovarian Cancer Risk Assessment and Prevention. Annual Reviews, 66, 93-113.
- People with breast cancer could have an enhanced risk of developing ovarian cancer, particularly if breast cancer has genetic mutations in the BRCA1 or BRCA2 genes, but this heightened risk primarily comes from shared genetic factors, not the disease itself.
- Research shows that people with breast cancer are approximately twice as likely to develop subsequent primary ovarian cancer, while ovarian cancer patients seemingly face a 1.6-fold increased risk of subsequent breast cancer, but the risk varies with the duration since their primary diagnosis.
- BRCA mutations are among the most significant shared risk factors for both ovarian and breast cancer, and about 30% of families with both cancers have BRCA1 gene mutations, while approximately 20% have BRCA2 mutations.
- Apart from BRCA, other shared risk factors for both cancers may include a family history of either cancer, older age, being overweight or obese, delivering their first child after the age of 30, never carrying a pregnancy to term, not breastfeeding, hormone therapy after menopause, and other genetic mutations.
- Certain risks, such as having had breast or ovarian cancer previously, remain unchangeable. However, managing fixed risks may involve regular mammograms, breast MRI scans, pelvic exams, transvaginal ultrasounds, CA-125 blood tests, and genetic testing for BRCA, BRCA2, and other relevant mutations to monitor and prevent the occurrence or spread of cancer. Additionally, modifiable risk factors include maintaining a moderate weight, regular exercise, limiting alcohol consumption, and discussing contraception options with a doctor.
