Radiation Therapy Oncology Group (RTOG) survival data on anaplastic astrocytomas of the brain: does a more aggressive form of treatment adversely impact survival?

The RTOG has sponsored several studies for malignant gliomas of the brain that have included tumors classified as either glioblastoma multiforme (GBM) or anaplastic-atypical astrocytoma (AAF) under the Nelson schema. Glioblastoma multiforme, the more aggressive histology, has done poorly under all forms of treatment having a typical median survival of 8-11 months. The less common and less aggressive anaplastic-atypical astrocytoma seems to show a survival that worsens with treatment more aggressive than standard radiotherapy. All patients in this report have had their tumors centrally reviewed by a RTOG neuropathologist and have had the diagnosis of anaplastic-atypical astrocytoma confirmed. We compare three patient groups: standard photon radiotherapy from the 60 and 70 Gy arms of RTOG 74-01/ECOG 1374 and from the 65 Gy control arm of RTOG 76-11; radiation therapy and chemotherapy from RTOG 74-01/ECOG 1374 (60 Gy + BCNU and 60 Gy + MeCCNU + DTIC) and from RTOG 79-18 (60 Gy + BCNU); and photon irradiation plus a neutron boost from RTOG 76-11 and RTOG 80-07. There are 47 analyzable cases treated with photons alone, 78 analyzable cases treated with photons + chemotherapy, and 38 analyzable cases treated with photons + neutron boost. Median survival for the three groups of patients is, respectively, 3.0 years, 2.3 years, and 1.7 years. Actuarial survival curves are presented for each subgroup of patients and then for the patient subgroups further broken down by major prognostic variables--age and Karnofsky performance status. In each "better prognostic category," the median survival decreased as the "aggressiveness" of the treatment increased. The implications of these findings for future clinical trials is discussed.