Years and years of research have shown that cancer almost always is a random occurrence, an unlucky mistake in the body that can have deadly consequences.

But on rare occasions, mutations in a person’s genetic makeup can greatly influence whether or not they get a particular cancer.

As scientists have unlocked more and more of the human genome, they’ve discovered a pair of genes that are closely related to breast and ovarian cancer. With those discoveries, doctors and genetic counselors now have a greater understanding of how to approach, monitor and treat the diseases.

“We’re always learning more about the risks associated with the gene, always learning more about how specific mutations are associated with risks, and learning more about treatment options,” said Dr. Erika Rager, a surgeon for Franciscan Physician Network Breast Specialists.

All humans have the BRCA1 and BRCA2 genes. They have been proven to produce tumor-suppressing proteins, an obvious advantage in keeping the body cancer free.

It’s only when the genes don’t work correctly that they are associated with an increased risk of breast and ovarian cancer.

Mutations on the BRCA1 and BRCA2 genes have proven to carry an 85 percent lifetime risk for breast cancer, and a 50 percent lifetime risk for ovarian cancer, said Morgan Dally, a genetics counselor with Franciscan St. Francis Health Cancer Center.

Dally works with patients who are concerned about the potential of cancer running in their families. She helps them examine their relatives and track the incidences of cancer among them, determining if they are a good candidate for genetic testing.

Dally doesn’t recommend that all people run out to get whole-scale genetic testing. The overwhelming odds are that most people will not have any mutation that could lead to cancer.

Most cancer cases are caused by nongenetic means, Dally said. The prudent route would be to start investigating cancer in your own family first, she said.

“It’s so important to know your family history. It’s surprising how many people know about how cancer runs in their families,” Dally said. “So it’s worth it to do a little digging, find out your history and ask you doctor if genetic counseling should be considered.”

When women — and occasionally men — are diagnosed with a mutation, they have three main options to consider, Rager said.

They can choose to monitor their breast tissue every six months, getting mammograms or MRI scans and physical exams at the hospital’s high-risk clinic.

Another option is called chemo prevention therapy, Rager said. Patients take a pill with low-dose chemotherapy medications, such as tamoxifen, which are used to treat patients with cancer but have also proved to help prevent development of the disease. Chemo prevention has shown to decrease the risk of getting breast cancer by 50 percent, Rager said.

The final level is preventive surgery in the form of a double mastectomy. The surgery will lower a woman’s risk of developing breast cancer by 90 percent.

“Unfortunately, we don’t have anything that’s 100 percent effective at preventing breast cancer, but the mastectomy lowers the risk the most,” Rager said.

To prevent ovarian cancer, doctors recommend patients with the BRCA mutation remove their ovaries by age 40, or as soon as they are done having children, Rager said. Because there is no good way to screen for ovarian cancer, removal is the best preventive option.

“We have powerful ways to screen for breast cancer, and if something comes up, we tend to catch it very early,” Rager said. “But that’s not the case with ovarian cancer.”

Insurance does pay for the testing, if patients meet family history requirements, Dally said. Very few of her patients have had to pay any significant out-of-pocket costs for the testing, and if their tests came back positive, most insurance covers the preventive screenings or surgeries.

“That’s a huge misconception, people thinking that this is only something the celebrities can have done. That’s not true,” Dally said.

Once a person has had the testing, they can work with their doctors for the best course of treatment, Rager said. Medical science has many options for those who do test positive, and more are being researched all the time.

The important thing is to not be so afraid of finding out you have the gene that you do nothing until it’s too late.

“If you don’t want aggressive surgery, that’s OK. But we do need to keep an eye on people,” Rager said. “The saddest thing I see is when there’s a history in their family and they didn’t get tested, then someone comes in with breast cancer. That’s heartbreaking.”

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By the Numbers

20 to 25 percent: Hereditary breast cancers attributed to a mutation in the BRCA1 and BRCA2 genes

10 to 15 percent: Percentage of all breast cancers attributed to a mutation in the BRCA1 and BRCA2 genes

85 percent: Lifetime risk for breast cancer by someone with the BRCA1 or BRCA2 mutation

12 percent: Lifetime risk on average for all women to get breast cancer

50 percent: Lifetime risk for ovarian cancer by someone with the BRCA1 or BRCA2 mutation

90 percent: Decrease in risk of breast cancer by patients with the gene mutation undergoing prophylactic surgery.

50 percent: Decrease in risk of breast cancer by patients undergoing chemoprevention treatment.

— Information from Dr. Erika Rager, surgeon for Franciscan Physician Network Breast Specialists, and the National Cancer Institute

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What are the BRCA genes?

BRCA1 and BRCA2 are human genes that produce tumor-suppressor proteins. These proteins help repair damaged DNA and ensure the stability of the cell’s genetic material.

What kinds of genetic tests are available to look for the mutation?

Several different tests are available, including tests that look for a known mutation in one of the genes and that check for all possible mutations in both genes. DNA is needed for mutation testing, and the sample is sent to a laboratory for analysis.

Who should consider genetic testing for BRCA1 and BRCA2 mutations?

Because harmful BRCA1 and BRCA2 gene mutations are relatively rare in the general population, the United States Preventive Services Task Force recommended that women who have family members with breast, ovarian, fallopian tube, or peritoneal cancer be evaluated to see if they have a family history associated with an increased risk.

How important is genetic counseling if there is family history of cancer?

Genetic counseling is generally recommended before and after any genetic test for an inherited cancer syndrome. This counseling should be performed by a health care professional who is experienced in cancer genetics.

How can a person who has a positive test result manage their risk of cancer?

  • Enhanced screening, or choosing to start cancer screening at younger ages than the general population or to have more frequent screening.
  • Prophylactic surgery to remove as much of the “at-risk” tissue as possible. Women may choose to have both breasts removed to reduce their risk of breast cancer, and may have their ovaries and fallopian tubes removed to reduce the risk of ovarian cancer.
  • Chemoprevention, or the use of drugs or other agents to try to reduce the risk of cancer.

— Information from the National Cancer Institute