Survival following combination chemotherapy in advanced high grade non-Hodgkin's lymphomas: relation to proliferative activity of the lymphoma cells.

In 18 untreated adult patients (median age 62.5 yr) with advanced non-Hodgkin's lymphoma of unfavourable histology, thymidine labelling indices (LIs) of the lymphoma cells were assessed. The patients were treated with combination chemotherapy and have been followed for 29-60 (median 52) months or until death. The survival curve had a steep fall during the first 2 yr. Between 2-5 yr after treatment there was a flattening of the curve and survival seemed to be similar to the survival expected for a Swedish population matched for age and sex. 11 patients died with 2 yr and 7 patients have survived for a longer period. Age, histopathologic classification and clinical stages were comparable in short-term and long-term survivors and treatment was not more aggressive for the long-term survivors. The LIs were significantly higher (median 8.2) in short-term survivors than in the long-term survivors (median 1.4). Long-term survival following combination chemotherapy of advanced NHL of unfavourable histology seems to be achieved mainly in patients with a low proliferative activity of the lymphoma cells. It is suggested that in NHL a high proliferative activity may facilitate the generation of new mutants and that some of these are spontaneously resistant to various chemotherapeutic drugs.