“Our study gives us the clearest picture of the impact of WBRT on cognitive function,” said Dr. Brown. “To date, we’ve really not had that.” Although many randomized clinical trials have identified WBRT as providing a significant benefit in controlling tumors, there have been no reports of benefits to survival. Instead, it seems that patients are adversely affected by WBRT, as side effects include hair loss, skin redness, dry mouth, and fatigue. On the other hand, radiosurgery on its own is generally safe, with minimal side effects and no associations with interruptions in chemotherapy.
Before any conclusions could be made about WBRT, Dr. Brown and his team needed to determine if the benefits of WBRT outweighed the negatives. “The question we were left with was understanding the toxicities associated with whole brain radiation therapy, specifically cognitive function,” explained Dr. Brown. “We needed to understand what’s worse – the cognitive impact of the whole brain radiation therapy, or, in other words, the therapy itself, or the recurrence of tumors.”
The impact of WBRT on cognitive functions were more significant than the control over tumors allowed by WBRT. At three and six months after receiving radiosurgery alone or radiosurgery with WBRT, cancer patients (majorly lung cancer patients) with brain metastases had similar rates of survival, although there was a significantly greater intracranial tumor control in the WBRT group. After three months of receiving radiosurgery alone or radiosurgery with WBRT, patients treated with WBRT had significantly more frequent cases of cognitive progression, which was defined as a significant decline in at least one of seven cognitive tests administered to the patients.
Immediate recall was most affected, followed by delayed recall and verbal fluency. Looking to also support these data with financial reasons, Dr. Brown will conduct a cost effectiveness analysis of adding WBRT to radiosurgery treatment. He is currently conducting an Alliance trial that uses WBRT or radiosurgery in the surgical cavity following surgical resection of tumors that metastasized to the brain, which will decide if one treatment is better than the other when compared head-to-head.
“Overtime there’s been a general shift in moving away from using whole brain radiation, in favor of stereotactic radiosurgery,” said Dr. Brown. “With these results and appropriate concerns for cognitive decline, it will likely will be pushed even further — reserving WBRT for later in a patient’s disease course.” This recommendation may sway the choice of treatment for some patients who need to undergo radiation therapy.