ImmunotherapyAntibody therapy
In 25-30% of all malignant breast tumors, a certain growth factor (c-erb2) and a receptor of the growth factor (HER-2 = human epidermal growth factor – receptor 2), which stimulates the cancer cells to grow faster, is produced in increased quantities. As a result, the cancer cells constantly receive signals from the growth factors formed that they should divide and multiply. The tumor thus grows (proliferates) faster than under a normal amount of growth factors.
Immunotherapy uses an antibody (Trastuzumab, Herceptin®) that is directed against these growth factors and receptors. As a result, the growth factor and receptor is no longer produced to the same extent, the cancer cells do not receive growth signals as frequently, grow more slowly and die. The formation of new blood vessels (angiogenesis) in the tumor cell cluster is also inhibited. Immunotherapy is used in combination with chemotherapy in patients who produce these growth factors and receptors.
What criteria are used to determine which therapy is used for treatment?
Which therapeutic measures are taken in breast cancer depends on which specific receptors are present in the tumor and how fast it grows. First of all, it must be said that in almost all cases surgery is indicated and only drug therapy depends on certain factors. To determine this, a biopsy (tissue sample) is taken during the diagnostic work-up of the breast cancer.
On the one hand, the diagnosis can be confirmed and on the other hand, it is immediately determined whether the tumor has receptors for the hormone estrogen (hormone receptor positive) and whether it has receptors for the growth factor HER2 (so-called HER2 positive tumors). If the breast cancer hormone receptor is positive, an anti-hormone therapy lasting several years is initiated after the operation. The best known preparations for this are tamoxifen, GnRH analogues and aromatase inhibitors (Aromasin).
Which of these drugs is used depends on whether the patient is already in the menopause or not. If the tumor also shows receptors for the growth factor HER2, antibody therapy with trastuzumab is given before and after surgery. The antibody binds specifically to the tumor cells and labels them for the immune system.
The tumor is recognized and fought by the immune system. Whether chemotherapy is administered as the last therapeutic step depends on the growth rate of the breast cancer and how similar it still is to normal breast tissue. In general, it can be said that chemotherapy is carried out for the majority of breast cancers.
An exception is the hormone receptor positive and HER2 negative breast cancer, which also has a low growth rate and is still very similar to normal tissue.Chemotherapy is not performed here because it has no benefit for the patient. In triple negative breast cancer, antibody or anti-hormone therapy is not effective because the tumor has no specific receptors for these therapies. Therefore, the only remaining treatment besides surgical removal of the tumor is chemotherapy.
The trend is to give chemotherapy before the operation. The advantage here is that the tumor shrinks due to the chemotherapy, which makes the subsequent operation easier or in some cases even possible. In addition, it is possible to test which chemotherapeutic agents are effective against the tumor and if chemotherapy is also given after the operation, experience has already been gained as to which chemotherapeutic agent is effective or not effective for the individual patient.
The standard chemotherapy for triple negative breast cancer is the drugs 5-fluoruracil, doxorubicin and cyclophosphamide. These are all chemotherapeutic drugs that attack the tumor in different ways. The combination of active substances can be modified depending on the patient’s previous illnesses and constitution. For example, doxorubicin would not be recommended for a patient with damage to the heart, as it has a toxic effect on the heart.
