Purpose: Results of radiation therapy for primary central nervous system lymphoma (PCNSL) were poor in the 1970-1980s, with most reported 5-year survival rates being less than 10%. To investigate whether the prognosis of PCNSL patients treated by radiation alone remains still poor, we investigated the results of radiation monotherapy in the 1990s.
Methods and materials: We collected data on 132 patients with histologically proven PCNSL treated by radiation alone in the 1990s from three nationwide or regional multiinstitutional studies conducted by the Japanese Society for Therapeutic Radiology and Oncology (JASTRO) Lymphoma Study Group or the Chubu Radiation Oncology Group. Follow-up data were updated as far as possible. Eleven patients who did not complete planned radiotherapy were included. The data were analyzed in relation to patient and tumor characteristics. The median patient age was 63 years, and the World Health Organization performance status (PS) was 3 or 4 in 40% of the patients. Multiple tumors were seen in 34%. Whole-brain irradiation with or without focal boost was used in 92%. The median radiation dose to the tumor site was 50 Gy (range, 8-74 Gy).
Results: For all 132 patients, the median survival time was 18 months and the 5-year survival rate was 18.0%. For 62 patients with PS 0-3 and aged 16-65 years (i.e., those eligible for the European Organization for Research and Treatment of Cancer 20962 study), the median survival was 26 months and 5-year survival was 24%. The 5-year survival was 25% for patients 63 years old or younger, and 9.8% for those older than 63 years (p = 0.0005). The 5-year survival was 22% for patients with PS 0-2 and 13% for those with PS 3 or 4 (p = 0.0040). Multivariate analysis confirmed the negative influence of higher age on patient prognosis.
Conclusions: The results of radiation monotherapy for PCNSL appear to have improved as compared with those reported previously. The results of new treatment should be evaluated in light of this finding. Since most prospective studies on the combined treatment exclude poor PS and high-age patients, the 5-year survival rate of 30% may not be regarded as a marked improvement over radiation alone.