Precision Medicine in Breast Cancer: Improving Care Options

Given that no two people are alike, it makes perfect sense that no two breast cancers would be alike either. It’s that kind of thinking that’s led to the development of a new type of medicine called precision medicine or personalized medicine.

Dr. Prarthna Bhardwaj, a medical oncologist at the D’Amour Center for Cancer at Baystate Health describes precision medicine as, “An approach to diagnosis and treatment that takes into account the genes you’re born with and the genes, or markers, present within any cancer cells you might have.”

By taking these individual factors into consideration, she explains, “Precision medicine enables healthcare providers to be more selective when choosing treatment options for an individual’s cancer, and better evaluate how well a treatment is working.”

Precision Medicine in Breast Cancer

For many years, breast cancer was viewed as one disease. But thanks to extensive research and studies, it’s now understood that there are many different types and sub-types of breast cancer that warrant different approaches to treatment.

“These findings are important for so many reasons,” says Dr. Bhardwaj. “With a better understanding of the specific type of breast cancer we’re dealing with as well as other factors unique to each person, we’re now in a position where we can tailor treatment appropriately.”

How Precision Medicine is Practiced

Precision medicine involves analyzing a patient’s blood or tumor tissue for genetic and molecular clues regarding what’s behind the presence of the cancer. In breast cancer, this type of testing is predominantly reserved for those with stage 4 cancers although there are several studies incorporating them in earlier stage setting.

One thing all breast cancers are tested for is a protein receptor called HER2.

Dr. Bhardwaj says, “HER2 is found in all breasts. In normal amounts, it helps cells divide and grow. But sometimes, something goes wrong, and your body makes too many of these receptors. This causes breast cells to grow and divide uncontrollably.”

Cancers that have higher than normal levels of the receptors are referred to as HER2-positive while cancers with normal, or in range, levels of HER2 are deemed HER2-negative.

Another common cause of cancer is genomic alterations, or mutations, within an individual’s genes. “Depending upon the type of gene affected, mutations can lead to uncontrolled cell growth or can prevent the body from fighting or preventing cancer growth,” says Dr. Bhardwaj. “In precision medicine, we use germline genetic testing to identify hereditary genetic alterations that can guide treatment decisions and have implications for blood relatives.”

Using Targeted Therapies for Personalized Treatment

Says Dr. Bhardwaj, “In several instances, we are able to delay chemotherapy for patients with stage 4 breast cancer based on the presence of specific genomic alterations in an individual. We’ve really gone from a one-size-fits-all approach to treating cancer to tailored treatment plans that are more holistic.”

The Future of Breast Cancer Care

While the advances in breast cancer treatment are significant, Dr. Bhardwaj says there’s a lot more work to be done.

“Precision medicine can make cancer treatment more effective but it’s not available for all types and subtypes of cancer. And some treatments are only available in clinical trials. In addition, out-of-pocket costs for some of these tests and targeted treatments can be high.”

Nonetheless, she encourages every person facing a diagnosis of breast cancer to ask their doctor the following questions when discussing their case:

• What kind of cancer do I have?
• Is it hormone positive?
• Is it HER2-positive?
• Do I qualify for genetic testing for hereditary cancer susceptibility genes?
• Do I qualify for special tumor testing for new treatments?

As Dr. Bhardwaj reminds patients, knowledge is power. Make sure you have all the information you need to understand your cancer and your options.