Is whole-brain irradiation necessary for primary central nervous system lymphoma? Patterns of recurrence after partial-brain irradiation.

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 > or = 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 (> or = 4 cm) appears to be worth further investigation.