Is whole‐brain irradiation necessary for primary central nervous system lymphoma?

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Abstract
BACKGROUND Neurotoxicity after whole‐brain irradiation remains a major problem in the treatment of primary central nervous system lymphoma (PCNSL). To clarify whether whole‐brain radiation is necessary for PCNSL, the authors retrospectively analyzed the outcome of patients treated with partial‐brain irradiation. METHODS A nationwide survey was performed regarding the treatment of PCNSL. Among 62 institutions surveyed, 7 were identified in which whole‐brain irradiation was not necessarily employed. Questionnaires were sent to these institutions and 43 patients who had been treated using partial‐brain fields since 1985 were collected. Thirty‐two patients had solitary lesions and 11 had multiple lesions. Patterns of recurrence could be identified in 38 patients. RESULTS The cumulative in‐field and out‐field recurrence rates at 5 years were 57% and 49%, respectively. Of 14 out‐field recurrences, 2 occurred at the safety margin of the previous radiation field. The out‐field recurrence rate was 45% in patients with a single lesion and 67% in those with multiple tumors (P = 0.79). The out‐field recurrence rate was 22% for patients treated with safety margins of ≥ 4 cm and 83% for those treated with safety margins of < 4 cm (P = 0.0079). The median survival time and the 5‐year survival rate were 28.5 months and 20%, respectively, in the former group of patients and 15 months and 11%, respectively, in the latter group (P = 0.057). CONCLUSIONS Focal radiotherapy with safety margins of < 4 cm appears to be associated with a very high rate of out‐field recurrence, but the use of a radiation field with generous safety margins (≥ 4 cm) appears to be worth further investigation. Cancer 2003;97:128–33. © 2003 American Cancer Society. DOI 10.1002/cncr.11035