If you’ve been diagnosed with triple-negative breast cancer (TNBC), you may wonder how this diagnosis will affect your life.

Some questions you may have are:

  • What is triple-negative breast cancer?
  • Is it treatable?
  • What will treatment be like?
  • What’s my long-term outlook?

The answer to those and other questions you may have will depend on several factors, such as the stage of the cancer and how well it responds to treatment. Keep reading to learn more about TNBC and your outlook.

If you’ve been diagnosed with breast cancer, one of the first things your healthcare team will do is determine whether the cancer cells are hormone receptive. Knowing if your cancer is sensitive to certain hormones will help direct your treatment, and it can offer insight about your outlook.

Some cancer cells have receptors for the hormones estrogen and progesterone, as well as an overexpression of the human epidermal growth factor receptor 2 (HER2) gene. If HER2 genes are overexpressed, the cells make too much of the protein HER2.

If your cells have hormone receptors, the hormones can fuel the growth of your cancer cells. Not all breast cancer cells have these receptors, and not all cancers overexpress the HER2 gene.

If your cancer isn’t sensitive to these hormones and doesn’t have an increased amount of HER2, it’s called triple-negative breast cancer (TNBC). TNBC represents 10 to 15 percent of all breast cancers.

Anyone can get breast cancer — including men — but it is most common in women under the age of 40. TNBC in men is extremely rare. Less than 1 percent of all breast cancers occur in men, and of these only 1 percent are TNBC.

In addition to being a woman of a younger age, other risk factors for TNBC include:

  • Genetics. People born with a mutation of the BRCA gene are more likely to develop TNBC. About 70 percent of all breast cancers diagnosed in people with the BRCA mutation are TNBC. Research shows that people with the BRCA1 mutation are more likely to develop TNBC than those with the BRCA2 mutation. Researchers are still trying to understand the link between the BRCA mutations and TNBC. Genetic testing will help you find out if you have this mutation.
  • Ancestry. Breast cancers diagnosed in African American and Hispanic women are more likely to be TNBC than in other groups. Doctors do not entirely understand why. Researchers are exploring the possibility that genetics are involved, including a person’s birthplace and associated ancestry, as well as lower income levels and inequities in healthcare.
  • Premenopause. Women who have not yet gone through menopause are at higher risk of getting TNBC. Research has not yet found why premenopausal women are at higher risk for TNBC.
  • Obesity. Obesity is one of the biggest predictors of all breast cancers.

The stage of breast cancer is based on the size and location of the tumor, as well as whether the cancer has spread beyond the part of the breast in which it originated. To determine the stage of breast cancer, healthcare professionals use a scale of stage 0 to stage 4.

Stage 0 breast cancers are isolated in one part of the breast, such as a duct or lobule, and show no sign of spreading into other tissue.

Stage 1 is typically localized, although further local growth or spread may cause the cancer to move into stage 2.

In stage 3, the cancer may be larger and has affected the lymph system. Stage 4 cancer has spread beyond the breast and nearby lymph nodes, and into other organs and tissues of the body.

In addition to stages, breast cancers are given grades based on the size, shape, and activity of the cells in the tumor. A higher-grade cancer means a greater percentage of cells look and act abnormal, or they no longer resemble normal, healthy cells.

On a scale of 1 to 3, with 3 being the most serious, TNBC is often labeled grade 3.

According to the American Cancer Society (ACS), the symptoms of TNBC can be the same as those for other types of breast cancer. ACS recommends regular screenings such as mammograms to detect breast cancer before symptoms appear, the time when treatment is most effective.

You may first notice breast cancer when there is a lump in your breast. A lump that is painless, hard, with irregular edges is the most common. However, the lump can also be soft or round. It may also be painful. Be sure to have any new lump or mass checked out by a healthcare professional.

Other signs of breast cancer include:

  • swollen breast or part of a breast, even if you don’t feel a lump
  • skin dimpling on the breast that often looks like an orange peel
  • breast or nipple pain
  • a nipple that turns inward, or has discharge other than breast milk
  • red, flaking, or thickened breast tissue or nipple
  • swollen lymph nodes

Any of these signs can be caused by other conditions. But it is always good to have them checked out by your healthcare professional.

Hormone therapy stops hormones from causing cancer growth. Because TNBC cells lack estrogen and progesterone, and their HER2 genes aren’t overexpressed, the cells don’t respond well to hormone therapy or medications that block HER2 receptors.

Instead of hormone therapy, treating TNBC often involves:

Like other types of breast cancer, TNBC can often be treated successfully if it’s caught early. However, in general, survival rates tend to be lower with TNBC compared to other forms of breast cancer.

Even though TNBC doesn’t usually respond to hormone therapy treatment, newer medications called poly ADP-ribose polymerase (PARP) inhibitors as well as immunotherapy are sometimes used to treat TNBC.

Finding a better treatment for TNBC is a major focus of breast cancer research.

Even though TNBC can be an especially aggressive type of breast cancer, your healthcare professional may or may not recommend aggressive treatment. The standard of care for TNBC is a chemotherapy backbone, either alone or in combination with other conventional therapies.

There are no scientifically recommended diets for the prevention or treatment of TNBC. However, ACS notes that 18 percent of all cancers and about 16 percent of cancer deaths in the United States relate to:

  • overweight
  • physical inactivity
  • alcohol
  • poor diet

They say many of these cancer cases may be prevented by following ACS recommendations on nutrition and physical activity. ACS recommends that your diet include:

  • nutrient-dense foods in amounts to maintain a healthy body weight
  • varied vegetables
  • fiber-rich legumes
  • whole fruits
  • whole grains

They recommend that you limit or avoid:

  • red and processed meat
  • beverages sweetened with sugar
  • highly processed foods

ACS says it is best not to drink alcohol. If you do, ACS recommends that women limit their intake to one drink per day, and men to two drinks per day.

Some research suggests that a category of plant compounds called polyphenols may reduce the risk of breast cancer. These compounds are plentiful in what is called the Mediterranean diet. They are found in:

  • olive oil
  • tea
  • chocolate
  • grapes

The isoflavones found in soy products are also thought to reduce breast cancer risk.

A 2016 study, while exploring why women with dense breasts tend to get TNBC more than others, found similar dietary associations. Researchers found a lower risk of TNBC associated with consumption of seafood, vegetables including vegetable fats, and nuts. A higher risk of TNBC was associated with animal fat, eggs, and meat.

A 2019 study found a greater risk of TNBC associated with a greater consumption of fructose, a common ingredient in artificially sweetened drink usually in the form of high-fructose corn syrup. However, researchers said more research is needed to definitively establish the link.

TNBC is also more likely than some other types of breast cancer to return after it’s been treated, especially in the first few years after treatment. There is a sharp decline in the rate of recurrence after the 5-year mark.

Learn more about the recurrence rate for triple-negative breast cancer.

The outlook for breast cancer is often described in terms of relative survival rates.

Relative survival rates are an estimate of the percentage of people who will survive their cancer for a given period of time after diagnosis. Survival among people with cancer is compared to survival among people of the same age and race who have not been diagnosed with cancer.

Five-year relative survival rates tend to be lower for triple-negative breast cancer (TNBC) than for other forms of breast cancer.

According to the American Cancer Society, the overall 5-year relative survival rate for TNBC is 77 percent. However, an individual’s outlook depends on many factors, including the stage of the cancer and the grade of the tumor.

Your healthcare professional will be able to give you a more precise outlook based on:

  • the stage of your TNBC
  • your age
  • your overall health

How well the cancer responds to treatment will also determine your outlook.

TNBC is often an aggressive cancer that is difficult to treat. It is also likely to spread and recur more than other breast cancers. But there are effective treatments available, and researchers are working on medication therapies that target TNBC.

It’s also important to remember that no one, not even your healthcare professional, can determine exactly how your breast cancer will progress or respond to treatment. Survival rates are based on statistics, but everybody has an individual experience with the disease that can’t be predicted.

Doctors do not know what causes TNBC. They believe that risk factors include genetics, ancestry, age, and obesity. Researchers have not yet learned know how to prevent TNBC. Your best option is to get regular screenings, such as mammograms, and quickly report any unusual symptom to your healthcare team.

Breast Cancer Healthline is a free app for people who have faced a breast cancer diagnosis. The app is available on the App Store and Google Play. Download here.