Overview

Triple-negative breast cancer (TNBC) is a rare cancer of the breast, which is very challenging to treat. About 10-20% of breast cancers are triple-negative.

In this type of breast cancer, the cancer cells do not have any of the receptor cells that are usually found in breast cancer.

When breast cancer tests negative for estrogen receptors, progesterone receptors, and HER2/neu receptors, it is referred to as triple-negative breast cancer. The growth of this type of cancer does not depend on the hormones estrogen and progesterone, or on the HER2 protein.

This implies that this type of breast cancer will not respond to hormone therapy nor to targeted therapy with chemotherapeutic agent Herceptin, which are the two most successful therapies for breast cancer.

Fortunately, chemotherapy still remains an effective option.

Nature of Triple-Negative Breast Cancer

  • This cancer usually belongs to the grade three type of breast cancer making it a very aggressive type of cancer with a worse prognosis than any other type of breast cancer.
  • The high grade of this cancer means that the cells look a lot different than the normal breast tissue cells and they proliferate much more rapidly.
  • This type of breast cancer is more likely to spread as compared to other types of breast cancer and is also more likely to recur after treatment.
  • It usually is basal-like cancer meaning that it resembles the basal cells that line the inner walls of the milk ducts. This is a new type of subtype of breast cancer that research has discovered.

Symptoms

TNBC symptoms are the same as symptoms of other breast cancer. The patient will experience:

  • A new lump in the breast
  • Swelling and pain in the breast
  • Dimpled skin over the breast
  • Nipple pain
  • Retraction of the nipple
  • The skin over the nipple may turn dry, may thicken, or turn red
  • Discharge from the nipple, which may be clear or blood-tinged
  • Swollen lymph nodes in the armpit or near the collarbone

Triple-Negative Breast Cancer Risk Factors and Prevalence

TNBC is more likely to occur in women with the following conditions

  • In women under the age of 50 years. Most hormone receptor-positive breast cancers appear in women aged 60 years and older.
  • Pregnancy and multiple childbirth increase the risks of triple-negative breast cancer.
  • t is commonly seen in American Africans and Hispanic women. Black women are three times more likely to get this breast cancer than white women. This type of breast cancer is less likely to be diagnosed in Asian women and non-Hispanic white women.
  • More common in women with obesity and physical inactivity.
  • It is commonly seen in women with a BRCA1 mutation. About 70% of breast cancers diagnosed in people with an inherited BRCA1 mutation are triple-negative breast cancer.

Prognosis and Survival rate

Triple-negative breast cancer is more likely to have spread at the time of diagnosis and is also more likely to recur after treatment. The prognosis is generally bad and worst when compared to other types of breast cancer.

The prognosis of this cancer is very poor due to a lack of response to hormone therapy and targeted therapy. About 10% to 20% of breast cancers are triple-negative.

Early relapse and metastasis (spread of breast cancer)  is common with this type of breast cancer. This risk is limited to the first three years or so and later the risk of recurrence and metastasis is the same as with other cancers.

The five-year survival rate for triple-negative breast cancer is lower than in other cancers. In a study of 2007, the 5 year survival in triple-negative cancer was found to be 77% against 93% in other breast cancers.

The following numbers give the stats taken from women diagnosed with triple-negative breast cancer between the years 2010 and 2016.

  • Localized: 91%
  • Regional lymph nodes: 65%
  • Distant metastasis: 12%

Diagnostic tests

On detecting a suspicious mass in the breast, your healthcare provider will order a mammogram. Based on the results of the mammogram, he will do a breast biopsy, remove the breast tissue, and send the biopsy sample to the path lab for analysis. The analysis will confirm the presence or absence of malignancy. If malignant, the lab will identify the stage and the grade of cancer.

The healthcare provider may also order further tests to find out details of the lumps such as their size and spread. These tests may include:

Besides, diagnosis of breast cancer also speaks of two specialized blood tests for breast cancer, the results of which decide whether the breast cancer will respond to hormone therapy and/or targeted therapy with Herceptin.

  • Hormone receptor test to determine if there are any hormone receptors on the surface of the breast cancer cells or not. They may have receptors for estrogen (ER-positive) or progesterone (PR-positive) or for both. This helps to find out if that particular breast cancer can be given hormone-blocking therapy or not to control its growth.
  • HER2/neu Test. HER2/neu is a cancer gene. In 20% to 30% of invasive breast cancers, this gene is amplified and the protein, HER2/neu protein, which it produces, is increased. This test helps to determine whether the cells of the breast cancer that is present in the patient are HER2 positive or not. HER2  positive test indicates that the tumor has HER2 protein receptors on the surface of its cells. Blocking of these receptors stops the tumor from growing. The chemotherapeutic drug, Herceptin blocks these protein receptors thereby inhibiting the growth of the tumor.

In triple negative breast cancer, all these three receptors are absent hence its name: Triple-negative.

Treatment of Triple-Negative Breast Cancer

With the ruling out of hormone therapy and targeted therapy with Herceptin, the choice of treatment for triple-negative breast cancer becomes limited to surgery, chemotherapy, and radiation. This cancer is aggressive and therefore, an aggressive line of treatment is usually suggested.

For example, given the choice, the oncosurgeon would prefer to do a mastectomy rather than a lumpectomy. The oncologist will also prefer more chemotherapy treatments or higher doses of chemotherapy.

He or she would also advise giving chemotherapy before surgery (neoadjuvant therapy) to shrink the tumor and obtain better results. This does help in getting better results after surgery by total eradication of cancer from the breast.

Post-surgery, your oncologist may also opt-in for radiation therapy to reduce the chances of recurrence.

Your oncologist may also order immunotherapy along with chemotherapy before surgery to shrink the tumor. You may receive immunotherapy for about a year after your surgery and post-surgery radiation.

Newer medicines called poly (ADP-ribose) polymerase inhibitors or PARP inhibitors are now approved by the FDA to treat triple-negative breast cancer.

Research, however, does appear to be showing promising results and it is positively hoped that a better form of treatment may soon materialize.


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