Prophylactic cranial irradiation reduced the 5-year rate of brain metastases, but did not improve overall survival in a randomized trial that evaluated 340 patients without disease progression following potentially curative treatment for locally advanced non–small cell lung cancer.
The findings provide important confirmatory information regarding the effectiveness of prophylactic cranial irradiation (PCI) in decreasing the rate of brain failures, Dr. Elizabeth Gore said in a press briefing from the Chicago Multidisciplinary Symposium in Thoracic Oncology.
The trial closed early because of slow patient accrual, however, and did not enroll enough patients to answer the primary question: whether PCI improves overall survival in patients with stage III NSCLC.
"I’d like to emphasize the need for participation in clinical trials. This is particularly important in lung cancer, which is understudied" despite its being the leading cause of cancer death in the United States, said Dr. Gore, professor of radiation oncology at the Medical College of Wisconsin, Milwaukee.
Over a median follow-up of 24.2 months for all patients and 58.6 months for living patients, the 5-year rates of brain metastases were 17.3% for those randomized to receive PCI delivered to 30 Gy in 15 fractions, compared with 26.8% for patients randomized to observation. That difference was statistically significant (P = .009).
However, there were no significant differences in the 5-year rates of survival, (26.1% for PCI and 24.6% for observation), or disease-free survival (18.5% and 14.9%, respectively).
Of the patients with treatment failures, 10% of those receiving PCI and 23% in the observation group experienced failure in the brain initially. Brain metastases (BM) were the only component of first failure in 9.1% and 21.5% of patients with and without PCI, respectively.
On multivariate analysis, PCI was significantly associated with decreased BM, whereas nonsquamous histology was associated with an increased risk of BM. The overall rate of BM in this trial was insufficient for reliable subset analyses by histology, Dr. Gore noted.
"Brain metastasis has a profound impact on patients with lung cancer in terms of quality of life. We need more information to determine which patients are most likely to derive a survival benefit from prophylactic cranial irradiation before this can become a part of standard management," she said.
The Chicago Multidisciplinary Symposium in Thoracic Oncology is sponsored by the American Society of Clinical Oncology, the American Society for Radiation Oncology, the International Association for the Study of Lung Cancer, and the University of Chicago.
Dr. Gore and her associates have no financial disclosures.