- Breast cancer and brain metastases
- breast cancer progression
- current treatments
- Two promising drugs
It is estimated that 10 and 16% of women with metastatic breast cancer develop metastases in the brain.
A percentage rises to 30% if autopsy data is included since it is typical for these metastases not to be detected correctly during the patient’s treatment.
Although the survival of patients with breast cancer has improved thanks to advances in diagnosis and treatment, the prognosis when brain metastases occur is still inferior, with survival rates of less than 50% in the first year.
Breast cancer with brain metastasis currently has no cure. Still, drugs are being studied to slow down the progression of the disease, making it chronic and alleviating its symptoms to maintain quality of life.
This is the objective of two clinical trials of the Catalan Institute of Oncology of Badalona promoted by the research company MEDSIR, which will test the efficacy of two treatments that can be an alternative to the current ones and thus improve the prognosis of the patients.
BREAST CANCER AND BRAIN METASTASES
“The breast cancer most predisposed to developing metastases in the brain is HER2, ” explains Dr Iris Teruel, medical oncologist at ICO, to Saber Vivir.
It is so called because it expresses the HER2 protein on the membrane of cancer cells, and this serves as a gateway to these cells.
“This does not mean that other breast tumours do not metastasise to the brain, but it is not as common as in the case of HER2”, says the oncologist.
Metastasis occurs when cells from a primary tumour, in this case, a breast tumour, can enter the bloodstream and settle in another part of the body.
Initially, any primary tumour can metastasise to a body organ. However, the reality is that there are certain types of cancer that, due to their characteristics, are more likely to metastasise in specific places.
In the case of breast cancer with brain metastases, the cancer cells have to cross the blood-brain barrier.
It is a kind of selective barrier that regulates the entry of blood that can be harmful to the brain (bacteria, viruses, drugs). HER2 breast cancer cells can cross the blood-brain barrier.
BREAST CANCER PROGRESSION
“Fortunately, most breast cancers are diagnosed locally, when they have not yet progressed. Only 5 or 10% are diagnosed as metastatic,” says the oncologist.
Once diagnosed, HER2 breast tumours usually progress within 3 to 5 years.
Age is one factor that increases the risk of brain metastasis in breast cancer. According to the Medsir portal for patients Living with cancer, the younger the patient, the greater the risk of brain metastasis.
However, it is also true that younger patients have a better prognosis. As for the symptoms of breast cancer with brain metastasis, the most common are:
- Headache, nausea, and dizziness.
- Neurological deficiencies can affect speech, vision or coordination due to pressure from tumours in an area of the brain.
Treatments have advanced in recent years, and the brain progression of breast cancer is slowing down, although there is room for improvement.
The usual therapies for breast cancer with brain metastases are radiosurgery and radiotherapy. Surgery is performed to remove the tumour, and radiotherapy is applied.
But when these treatments do not stop the progress of metastasis, there is no specific therapy for these patients.
No chemotherapy drugs or targeted therapies work because they cannot cross the brain’s blood-brain barrier, the protective barrier between blood vessels and brain fluid, preventing drugs from getting where they need to work.
TWO PROMISING DRUGS
The Badalona ICO has two clinical trials underway to test the efficacy of two drugs:
One of them is trastuzumab deruxtecan . This drug will be tested in patients with HER2-positive advanced breast cancer who have brain metastases and whose cancer has progressed after receiving local treatment.
“Trastuzumab deruxtecan is an antibody directed against HER2, a protein responsible for the spread of cancer cells in this type of breast cancer. In preliminary studies, this drug has already given very positive results, ” says Dr Iris Teruel.
If the results of this trial called DEBBRAH are good, the drug could be used as a treatment option in all patients with metastatic breast cancer, regardless of brain metastases.
It is a low-toxic treatment that could avoid options such as radiotherapy to the whole head, which does have significant toxicity.
On the other hand, the PHENOMENAL clinical trial will evaluate the efficacy of another drug, liposomal irinotecan, in patients with HER2-negative breast cancer, that is, those who do not express the HER2 protein.
This drug works by preventing DNA from replicating when a new cancer cell is going to form, which helps to stop the growth and development of the tumour.