Treating four or more brain tumors in a single radiosurgery session resulted in improved survival compared to whole brain radiation therapy alone, according to a study the University of Pittsburgh School of Medicine presented today at the 47th Annual Meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO) in Denver.
"Cancer patients with multiple metastases to the brain face very grim prognoses and limited treatment options," said John Flickinger, M.D., senior author of the study and professor of radiation oncology at the University of Pittsburgh School of Medicine. "In the past, these patients were not considered candidates for radiosurgery. The results of our study indicate that treating four or more brain tumors with radiosurgery is safe and effective and translates into a survival benefit for patients."
Two hundred and five patients with primary malignancies that had metastasized to the brain underwent gamma knife radiosurgery for four or more tumors during one session. Gamma knife is a non-invasive, computer-driven, bloodless brain surgery that uses cobalt 60 to destroy tumors and vascular malformations and requires no surgical incisions. The average number of brain tumors for patients in the study was five, with a range from four to 18. Radiosurgery was used alone, in combination with whole brain radiation or after failure of whole brain radiation.
Radiosurgery patients with the most prognostic factors associated with survival from brain metastases (defined as class 1 according to the Radiation Therapy Oncology Group classification system for patients with brain metastases) survived an average of 18 months, compared to a reported historical average of seven months for those who received whole brain radiation alone. Patients defined as class 2 who received radiosurgery survived nine months compared to the historical average survival of four months for patients who received whole brain radiation. Patients with the least prognostic factors associated with survival (class 3) who received radiosurgery survived an average of three months compared to the historical average survival of two months for patients who received whole brain radiation. The average overall survival for patients who received radiosurgery was eight months and the average time to progression and new brain metastases was nine months.
"The study also found that the sum of the volume of all treated brain tumors was a more significant predictor of length of survival than was the total number of brain metastases, indicating that tumor volume should be used as a criterion for radiosurgery rather than number of brain metastases," added L. Dade Lunsford, M.D., Lars Leksell professor and chairman of the department of neurological surgery at the University of Pittsburgh School of Medicine.
"Typically, only patients with one to three brain metastases are considered candidates for stereotactic radiosurgery," said Ajay K. Bhatnagar, M.D., study presenter and resident, department of radiation oncology, University of Pittsburgh School of Medicine. "However, based on the results from this study, we conclude that the number of brain metastases should not necessarily preclude patients with multiple lesions from this potentially life-saving treatment option."
Also involved in the study from the University of Pittsburgh's departments of radiation oncology and neurological surgery was Douglas Kondziolka, M.D.