Q.) Can radiation to my brain affect my ability to think (my neurocognitive function)?
A.) This is an important question has traditionally been not very well understood, but recent studies have given us some important insights on the issue.
One recent study looked at patients receiving whole brain radiation therapy (WBRT) to the brain for brain metastases. These patients had their neurocognitive function tested at baseline (before treatment), and in regular intervals afterwards. (1)
This study noted that even before treatments started, many patients had a decline in their neurocognitive function, which related to the size of the tumor in the brain.
Those who had a good response to radiation treatments, determined by a decrease in the size of the tumor, score higher in subsequent neurcognitive testing. Patients who had a decline in their neurocognitive function were likely to be ones who had progressive brain disease.
There have also been studies done looking at neurocognitive function of patients who received Prophylactic Cranial Irradiation for Small Cell Lung Cancer– that is, patients who did not have known cancer in the brain, but received radiation to prevent it from occurring. Again, no decline in neurocognitive function was seen that was attributable to radiation. (2), (3) That’s why patients with limited stage small cell lung cancer who respond well to treatment to the lung routinely get prophylactic whole brain radiation– the benefits far outweigh the risks of treatment.
One major caveat– the studies mentioned have all been done on adults. For children, the story is different. They are at a phase in life when their central nervous system can be at a pivotal point in development. Unfortunately, this means that they are far more senstive to the effects of brain radiation than adults. The studies on the effects of radiation therapy to the brain on children have detected statistically siginifcant declines in neurocognitive function. Children who are receiving radiation therapy to the brain will require referrals with experts who are experienced in understanding the cognitive effects of radiation therapy in their age group.
References:
(1) Li J, Bentzen SM, et al. Regression after whole-brain radiation therapy for brain metastases correlates with survival and improved neurocognitive function. J Clin Oncol. 2007 Apr 1;25(10):1260-6.
(2) Arriagada R, Le Chevalier T, et al. Prophylactic cranial irradiation for patients with small-cell lung cancer in complete remission. J Natl Cancer Inst 1995 Feb 1;87(3):183-90.
(3) Gregor A, Cull A, et al. Prophylactic cranial irradiation is indicated following complete response to induction therapy in small cell lung cancer: results of a multicentre randomised trial. United Kingdom Coordinating Committee for Cancer Research (UKCCCR) and the European Organization for Research and Treatment of Cancer (EORTC). Eur J Cancer. 1997 Oct;33(11):1752-8.