Do Your Genes Increase Your Risk of Getting Cancer Twice?

Study highlights the risks of genetic mutations

DNA in test tubes

If you knew you had an 85 percent lifetime risk of breast cancer — a risk six and a half times higher than for most women — would you be more vigilant?

Advertising Policy

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

If you knew your risk of developing a second cancer was eight times higher than most people’s, would you talk to your doctor right away?

These questions are not meant to be scary. They’re the types of questions patients with genetic mutations need to ask. They can save your life.

Our most recent research shows that people with a certain genetic mutation are much more likely to develop cancer a second time. Knowing about such risks helps you, as a patient, make better decisions about screening and treatment.

What the study shows

“A second ‘primary’ cancer is completely different. It’s a distinct type of cancer from the first, and it can strike different parts of your body.”

Charis Eng, MD, PhD

Advertising Policy

Founding Chairwoman of the Genomic Medicine Institute

When I say “second cancer,” I do not mean a recurrence of the same type of cancer. A second “primary” cancer is completely different. It’s a distinct type of cancer from the first, and it can strike different parts of your body.

To study this risk, our research group followed 114 patients with a PTEN gene mutation for seven years. Out of those patients, 40 percent developed a second primary cancer.

The results are stunning. According to our analysis, people with this PTEN mutation are nearly eight times more likely than the general population to develop a second cancer. For women, the risk of a second primary breast cancer is nine times higher. For endometrial cancer, it’s 14 times higher.

For people with inherited cancer genetic mutations, knowing about this increased risk matters, both for treatment and monitoring.

What the results mean for patients

Once a patient knows about a PTEN mutation — or other high-risk mutations — screening and monitoring must become a lifetime habit.

Advertising Policy

For example, a high-risk woman may need to start MRI screenings and mammograms earlier than the general population. She also needs to continue them indefinitely, remaining vigilant for life.

But better screening isn’t the only important outcome. Women with an especially high risk of breast cancer — both a first and second type — should discuss prophylactic (preventive) mastectomy with a doctor. It’s a hard conversation to have, but when your risk is so high, it’s also worthwhile.

Likewise, we found that men with the PTEN mutation have a much higher risk for a second primary thyroid cancer. That has implications for surgery. Often a surgeon treating thyroid cancer will leave part of the thyroid intact. But for men with such a high risk, the surgeon may want to remove all of the thyroid. Doing so would decrease the man’s chances of developing a second cancer.

We hope other independent researchers will validate our results in their own studies. In addition, future research should explore whether other genetic mutations increase the risk for second primary cancers. This study is just a first step in understanding a little-known risk — and how patients can decrease it.

[Tweet “New study: Genes affect your risk of getting #cancer not only a first time, but also a second.”]

Charis Eng, MD, PhD

Charis Eng, MD, PhD

Charis Eng, MD, PhD is founding chairwoman of the Genomic Medicine Institute and founding director of its Center for Personalized Genetic Healthcare. Dr. Eng is a global leader in cancer genetics and cancer genomic medicine.
Advertising Policy