Population-based analysis of incidence and outcome of transformed non-Hodgkin's lymphoma.
OBJECTIVE
To assess the incidence and predictive factors for development of transformed lymphoma in a population-based series of patients with follicular lymphoma (FL).


METHODS
The Lymphoid Cancer Database was used to identify patients with FL diagnosed and treated in the province of British Columbia, Canada. Transformed lymphoma was defined as the development of aggressive non-Hodgkin's lymphoma (NHL) in patients with FL. Factors present at the time of initial diagnosis of indolent NHL and at transformation were analyzed for their impact on risk of transformation and subsequent outcome.


RESULTS
Between 1986 and 2001, 600 patients with newly diagnosed FL met the inclusion criteria. With a median follow-up of 109 months (range, 10 to 244), 170 (28%) developed transformation, 107 (63%) based on biopsy confirmation. The annual risk of transformation was 3% continuously through 15 years. A multivariate analysis of clinical factors at diagnosis identified advanced stage as the only predictor of future transformation. The median post-transformation survival was 1.7 years. The 5-year survival was superior for patients with limited extent transformation compared with those with advanced cases (66% v 19%, P < .0001). Patients with transformation based on clinical versus histological criteria had an identical median survival of 1.8 years (P = .2).


CONCLUSIONS
The annual risk of transformation of FL is 3% continuing without plateau beyond 15 years. Advanced stage at diagnosis is predictive of future transformation. Clinically diagnosed transformation has an equal impact on outcome as biopsy proven transformation.
Division of Medical Oncology, Fraser Valley and Vancouver Cancer Centers and the Department of Pathology and Biostatistics, British Columbia Cancer Agency and the University of British Columbia, Vancouver, BC, Canada. aaltoura@bccancer.bc.ca
Abdulwahab J
AJ
Al-Tourah
Karamjit K
KK
Gill
Mukesh
M
Chhanabhai
Paul J
PJ
Hoskins
Richard J
RJ
Klasa
Kerry J
KJ
Savage
Laurie H
LH
Sehn
Tamara N
TN
Shenkier
Randy D
RD
Gascoyne
Joseph M
JM
Connors
D000328:Adult; D001706:Biopsy; D001955:British Columbia / Q000453:epidemiology; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008224:Lymphoma, Follicular / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology / Q000628:therapy; D008228:Lymphoma, Non-Hodgkin / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011159:Population Surveillance; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome