Understanding triple-negative breast cancer

With breast cancer being the most common type of cancer among women in the United States excluding skin cancer, you may know someone who has been diagnosed.

A diagnosis may start with imaging such as a mammogram or ultrasound. If the imaging exam reveals an area of concern, a doctor will order a biopsy to analyze a small sample of tissue under a microscope.

A definitive breast cancer diagnosis is determined from the pathology report, which is written after tissues from the biopsy are examined.

“A breast cancer patient’s pathology report is important because it informs medical professionals about the specific type of breast cancer and how we can best treat it,” says Dr. Heather Tracy, an oncologist with Sharp Community Medical Group and affiliated with Sharp Memorial Hospital.

After a diagnosis

Once a diagnosis of breast cancer is made, a patient may undergo surgery to remove the cancer. The pathology report from this procedure includes:

• The type of tissue in which the breast cancer originates and whether it is invasive or noninvasive

• Tumor size and grade (a measure of how abnormal cancer cells look and how quickly they may grow)

• Margin status (whether cancer cells are present at the edge of the removed tissue) — this is only determined on the final surgical pathology as opposed to the biopsy

• Hormone receptor status, including ER and PR (whether the cancer cells have estrogen or progesterone receptors that indicate the cancer is fueled by these hormones and may respond to medications that block the effects of these hormones on the cancer cell)

• HER2 status (shows whether the cancer has high levels of the HER2 protein, which can fuel cancer growth and is responsive to certain targeted treatments)

Triple-negative breast cancer

A rare type of breast cancer called triple-negative breast cancer (TNBC) lacks estrogen, progesterone and HER2 receptors.

“With TNBC, we are not able to use hormone or targeted therapies and will need to use chemotherapy and possibly immunotherapy to prevent breast cancer recurrence,” says Dr. Tracy.

Approximately 10% to 15% of breast cancer diagnoses are TNBC. These cancer subtypes tend to grow more quickly and have a higher likelihood of returning after treatment. However, treatments have improved over time and have led to better outcomes.

“While treatment of TNBC has historically been more challenging, we now have many new therapies to treat this subtype,” says Dr. Tracy. “Depending on the cancer stage at diagnosis, we can consider surgery, radiation therapy, neoadjuvant (before surgery) and adjuvant (after surgery) chemotherapy and immunotherapy.”

Neoadjuvant chemotherapy helps shrink large tumors and targets cancer cells that have spread to lymph nodes before surgery. This helps to make sure margins are clear at surgery and potentially kills cancer cells that have spread to the lymph nodes, ultimately helping to minimize need for a more extensive surgery.

Immunotherapy, a type of treatment that helps the immune system recognize and attack cancer cells, has been shown to be very effective against TNBC. This may be given before and after surgery, depending on the stage of the TNBC at diagnosis.

Risk factors and symptoms

Although researchers do not yet know the exact cause of TNBC, mutations in certain breast cancer genes have been linked to a higher risk. TNBC is also diagnosed more often in women younger than 40 and in women with Black or Hispanic ethnicity.

TNBC symptoms are similar to those of other breast cancer subtypes and can include:

• Breast swelling

• Skin dimpling

• Breast or nipple pain

• Flaky, thickened or red skin on the breast or nipple

• Nipple discharge

• An inverted nipple

Swollen lymph nodes under the arm or near the collarbone

“Consult your doctor if you have any of these signs or symptoms,” says Dr. Tracy. “Make sure to get routine breast exams and mammograms, live a healthy lifestyle that includes regular exercise, and talk to your doctor if you have family history of breast cancer.”

She adds that while a TNBC diagnosis can feel discouraging, there are many new effective treatments to help treat the disease. The key is to catch TNBC at the earliest stages, which is why breast cancer screening is incredibly important.

Learn more about breast cancer; get the latest health and wellness news, trends and patient stories from Sharp Health News; and subscribe to our weekly newsletter by clicking the "Sign up" link below.