Long-term survival after histologic transformation of low-grade follicular lymphoma.

PURPOSE: To describe the course of patients following histologic transformation (HT) from low-grade follicular lymphoma to intermediate- or high-grade non-Hodgkin's lymphoma. PATIENTS AND METHODS: Patients were identified from data bases in the Division of Oncology and the Department of Surgical Pathology. HT was defined as the conversion of a follicular small cleaved-cell or follicular mixed small cleaved-cell and large-cell lymphoma to a diffuse large-cell, diffuse mixed small cleaved-cell and large-cell or any high-grade lymphoma. RESULTS: We analyzed the clinical course of 74 low-grade lymphoma patients with histologically proven transformation occurring from 1965 to 1988. The median time from diagnosis to HT was 66 months, and the median age at HT was 58 years. The median duration of survival after transformation was 22 months. Anatomic extent of disease at HT (limited v extensive, P = .01), prior chemotherapy (none v any, P = .01), and response to therapy (complete v partial or none, P = .005) at time of HT were identified as significant predictors of survival after HT in backward-selection Cox regression analysis. Thirty patients attained a complete response to therapy at HT. They had a median survival duration of 81 months after HT. CONCLUSION: A subset of patients with HT from low-grade follicular lymphoma to intermediate- or high-grade lymphoma enjoys relatively long-term survival. Patients with limited disease and no previous exposure to chemotherapy have the most favorable prognosis.