For decades, medical science treated breast cancer and ovarian cancer as two completely separate diseases that just happened to affect the female reproductive system. Today, oncologists view them as closely linked biological cousins. Understanding this connection is one of the most powerful tools women have for proactive health management and early detection.

Here is a breakdown of what connects these two cancers, who is most at risk, and what steps you can take.

The Genetic Thread: BRCA1 and BRCA2

The primary link between breast and ovarian cancer lies in our DNA. We all have BRCA1 and BRCA2 genes. In their normal state, these are tumor-suppressor genes—they act like a biological repair crew, fixing damaged DNA and preventing cells from growing out of control.

However, when a person inherits a mutated or altered version of a BRCA gene, the body’s ability to repair cell damage is compromised. This drastically raises the risk for both cancers:

  • Breast Cancer Risk: While the average woman has about a 13% chance of developing breast cancer in her lifetime, women with a BRCA mutation face a 45% to 85% lifetime risk.
  • Ovarian Cancer Risk: The average lifetime risk is quite low—around 1.2%. However, for women with a BRCA1 mutation, that risk jumps to 39% to 44%, and for BRCA2, it rises to 11% to 17%.

Beyond BRCA: Shared Risk Factors

While genetics play the largest role, these two cancers also share common environmental and hormonal influences:

  • Estrogen Exposure: Extended exposure to estrogen over a lifetime can influence both diseases. Factors like starting menstruation at an early age (before 12) or entering menopause later than average can slightly elevate risks.
  • Family History: Even without a known BRCA mutation, having multiple close relatives (mother, sister, daughter, or aunt) diagnosed with either breast or ovarian cancer significantly increases a woman’s risk profile.

💡 The Protective Factor of Pregnancy and Breastfeeding: Interestingly, factors that temporarily pause ovulation and lower lifetime estrogen exposure—such as multiple full-term pregnancies and breastfeeding—have been shown to actively lower the risk of developing both types of cancer.

Proactive Steps: Knowledge is Protection

Because ovarian cancer is notoriously difficult to detect in its early stages due to vague symptoms (like bloating or abdominal pain), understanding your risk factors is essential.

If you have a strong family history of either cancer, consider speaking with a doctor about genetic counseling. A simple blood or saliva test can determine if you carry a BRCA mutation. Knowing this information allows you and your healthcare team to create a personalized screening plan, which may include more frequent MRIs, mammograms, or preventative options to keep you safe.