Prognostic factors and a predictive model of follicular lymphoma: a 25-year study at a single institution in Japan.

The incidence of follicular lymphoma in Japan is far lower than that in western countries, and no large-scale clinicopathologic studies on this neoplasm have been conducted in Japan. We reviewed histopathological specimens from 118 of 135 patients who had been diagnosed as having follicular lymphoma between 1968 and 1993. Prognostic factors influencing survival were analyzed using univariate and multivariate analyses. Factors that were independently significant upon multivariate analysis were incorporated into a predictive model. Ninety-three patients (78.8%) had a confirmed diagnosis of follicular lymphoma. Twenty-one of the remaining 25 patients were categorized as having other lymphoma subtypes, and four patients showed indefinite findings or those suggesting diseases other than lymphoma. Major characteristics of the 93 patients with follicular lymphoma were a median age of 53 years (20-85); 59 males (63%) and 34 females (37%); small cleaved cell type in 33 (35%), mixed cell type in 41 (44%) and large cell type in 19 (20%); stage I/II in 41 (44%) and stage III/IV in 50 (54%). Overall survival was 71% at 5 years, 58% at 10 years, and 43% at 15 years with a median survival of 13.3 years. Multivariate analysis revealed that two variables, age (>60) (P=0.001) and the serum LDH level (>1 x normal value) (P=0.026), were unfavorably significant prognostic factors influencing survival. The predictive model using these two variables identified three risk groups with estimated five-year survival rates of 88.5%, 56.8%, and 31.5%. Age and serum LDH were significant predictors of survival in Japanese patients with follicular lymphoma. Our predictive model may provide a basis for future therapeutic trials against follicular lymphoma in Japan.