Five-year outcomes were reported from a randomized clinical trial conducted to determine whether prophylactic cranial irradiation extends the survival of patients who receive it, and also to determine if it is safe when administered in low doses. The Radiation Therapy Oncology Group (RTOG) 0214 clinical trial enrolled 340 patients receiving treatment at 127 cancer centers starting September 2002. Due to low enrollment, the clinical trial was closed in August 2007 without reaching its accrual target of 1,058 patients.
All of the patients had either undergone surgery or radiation therapy as initial treatment for their lung tumors. Some also had completed chemotherapy treatments. Among the 340 patients, 163 patients received 30 Gy of radiation, delivered in 2-Gy fractions for 15 days. One hundred seventy-seven patients did not receive this treatment and were placed under observation.
Principal investigator Dr. Elizabeth Gore, professor of radiation oncology at the Medical College of Wisconsin, reported that after a median follow-up of 24.2 months for all patients and 58.6 months for living patients, 17.3% of those who received cranial irradiation developed brain metastases. By comparison, this rate was 26.8% for those who did not receive cranial irradiation.
Irradiation had no impact on survival, however. Five-year overall survival was 26.1% for patients who received cranial irradiation and 24.6% for those who did not. The difference was not statistically significant, Gore said.
She explained that because enrollment in this clinical trial was so low, attaining only about one-third of the goal, it was not possible to answer either one of the clinical questions posed.
"However, we're able to confirm that the risk of developing brain metastases by these patients is dramatically reduced if they receive prophylactic cranial irradiation," she said. Up to half of all patients with NSCLC develop brain metastases if they live long enough, and because local control of NSCLC is improving with improved treatment, the likelihood of metastasis occurring in such a patient's lifetime is increasing without radiation treatment. Chemotherapy decreases failures outside the chest, but it does not enter brain tissue.
Gore did not state whether patients who received cranial irradiation had experienced neurocognitive decline, including both short-term and long-term memory loss; nor did she or her colleagues advocate if this should be performed. Rather, she emphasized the need to encourage patients with lung cancer, the leading cause of cancer death in the U.S., to enroll in clinical trials.