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Breast cancer is not a single disease – there are several hundreds of its different varieties. They differ in the aggressiveness and response to treatments. The differences reflect the underlying biochemical and genetic changes that are specific to every patient. Knowing what type of breast cancer a patient has got is critical for choosing the most appropriate treatment strategy.
The majority of breast cancers possess excessive amounts of specific protein molecules called receptors. Receptors are located on the surface of cancer cells and bind to various hormones and factors that stimulate their growth. As a rule, many breast cancers grow faster in response to normal female sex hormones such as estrogen and progesterone. Many modern anticancer therapies aim to disrupt this interaction and thus stop the progression of tumor.
Triple-Negative Breast Cancer is a specific type of disease with poor prognosis
The term Triple-Negative Breast Cancer (TNBC) refers to a group of tumors that lacks estrogen, Her2/Neu and progesterone receptors. As a result, these tumors are not sensitive to the corresponding hormones and growth factors circulating in the blood stream, but also don’t respond to the hormonal therapies that work for the majority of other breast cancers.
The TNBCs represent approximately 15-20% of all breast cancer cases.
Since the TNBC shows very little or no response to the available anti-cancer agents, it represents a significant clinical challenge. The triple negative breast cancer tumors are linked with shorter time of relapse (return of disease after initial surgery and treatment) and high mortality rate. Within the TNBC group itself, there are many distinct biological subtypes. Therefore, the precise identification of biological markers and prognostic factors for each individual patient should be done from the beginning. Once it is done, the treatment regimens can be designed against the specific types of TNBC.
Treatment difficulties associated with triple negative breast cancer
The treatment options and prognosis for breast cancer often depend on the particular subtype that the patient is having. In the absence of a trustworthy prognostic marker for TNBC, the treatment regime suffers significantly. In addition, the early stages of TNBC are often missed during the mammographic investigation thus delaying the diagnosis and the beginning of treatment.
The prognosis of triple negative breast cancer is very poor as compared to the hormone responsive breast cancer forms. In part, this is a result of unavailability of targeted, specific treatment for this breast cancer type. There are now drugs available that are targeted against the HER2 and estrogen receptors encountered in the majority of breast cancer cases. These drugs selectively attack the breast cancer cells without affecting the normal cells. However, in the case of TNBC these drugs prove futile due to the absence of the corresponding receptors.
As an alternative, physicians have been using older chemotherapeutic drugs in the treatment of patients with TNBC. Multiple side effects of these drugs limit the dose the patient can receive which often makes therapy inefficient.