Protecting specific area of the brain during a radiation therapy substantially reduces memory loss in the cancer patients, a new study shows.
According to the study, protecting the stem cells that reside in and around the hippocampus substantially reduces the rate of memory loss in the cancer patients during whole-brain radiotherapy without a significant risk of recurrence in that area of the brain.
Hippocampus are C-shaped area in the temporal lobe on both sides of the brain that are associated with the ability to form and store memories.
“Memory loss, especially short-term recall, is an important consideration for patients receiving whole-brain radiotherapy,” says the study’s co-principal investigator, Minesh P. Mehta, M.B., Ch.B., professor of radiation oncology at the University of Maryland School of Medicine. “We found that reducing the radiation dose to the stem-cell niches surrounding the hippocampus during treatment was clearly associated with memory preservation without an inordinate risk of relapse in that portion of the brain. The findings far exceeded our expectations.”
A total of 113 patients were recruited between 2011 and 2013; investigators were able to evaluate 42 patients at four months and 29 patients at six months.
Patients in the study, the majority of them with lung cancer that had spread to the brain, were treated with intensity-modulated radiation therapy (IMRT), which enabled doctors to shape the radiation beams to avoid the hippocampus.
Researchers used a standardized cognitive function assessment — the Hopkins Verbal Learning Test (HVLT) — to measure patients’ baseline memory, such as their ability to recall information immediately or after a delay, with follow-up at two, four and six months.
Dr. Mehta says that the radiation affects cognitive function by damaging nerve cells as well as stem cells, which help to regenerate nerve cells that support memory formation. “These stem-cell niches are exquisitely sensitive to radiation and are involved in neurogenesis — the process of generating new neurons, or nerve cells. Although we call it hippocampal-avoidance radiotherapy, we really are targeting the stem-cell niches in and around the hippocampus,” Dr. Mehta says.