Brain tumors: type of radiation is crucial

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Many types of tumors spread to the brain and metastasize there. With radiation one tries to fight the cancer there. Which form of radiation is chosen plays a decisive role in how long the patient survives.

Headache, paralysis, psychological changes, epileptic seizures: these can all be signs of brain tumors. Then action must be taken quickly, because without therapy, the mean survival rate after diagnosis is only one to two months.

Whole brain versus individual metastases

In the standard therapy, the brain metastases are irradiated. There are two possibilities: Either the entire brain is exposed to the radioactive radiation or one only aims at the metastases. The second method spares healthy brain tissue, which is called stereotactic radiosurgery.

Researchers led by Lia Halasz from the University of Washington Medical Center retrospectively analyzed the data from almost 800 patients with non-small cell lung or breast cancer. In all study participants, the tumors had also metastasized in the brain, with a maximum of four, less than four centimeters in diameter. Almost 30 percent of lung cancer patients and 13 percent of women with breast cancer had stereotactic radiosurgery, the rest had whole-brain radiation.

Increasing survival rates

For both types of cancer, the survival time with the specific radiation increased significantly, by 42 (lung cancer) and 46 percent (breast cancer) compared to holistic radiation. So far, the study authors can only guess the reason for this difference. Particularly in the case of tumors that have developed a certain resistance to radiation, specific irradiation could be advantageous because higher doses of radiation can be used here. "The study confirms the current trend away from whole-brain radiation, at least as an early therapeutic measure," says Michael Weller from the German Society for Neurology.

However, since the study only evaluated the patient data retrospectively, it also has weaknesses. "The respective therapy was probably assigned to the patient for certain reasons and not at random," says Weller. The authors therefore tried to compensate for influencing factors such as the number and size of the tumors using statistical methods. Nevertheless, they also write that further investigations are necessary in order to be able to draw reliable conclusions.

Frequent route to the brain

More than a quarter of all malignant tumors lead to brain metastases. The types of cancer examined in the study are particularly common. These metastases are also known as secondary brain tumors because they are caused by another cancer. They are much more common than primary brain tumors, which are where the cancer develops in the brain from the start. (away)

Source: Halasz L. M. et al .: Comparative effectiveness of stereotactic radiosurgery versus whole-brain radiation therapy for patients with brain metastases from breast or non-small cell lung cancer, Cancer 2016, 122: 2091 - 100.

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