Forty-five patients with stage III-IV low grade non-Hodgkin's lymphoma (NHL) were treated with a non-intensive polychemotherapy regimen including chlorambucil-vincristine and cytarabine (Ara-C), termed COA, for a total of 366 courses, beginning in June 1986. Grade 4 myelotoxicity occurred in only 4/45 patients. No treatment related death was observed. All patients were evaluable for response. Overall, 38 (84%) objective responses, including 31 (69%) complete responses (CR), were observed. At a median follow-up of 57 (21-84+) months, only 8 deaths occurred. Twenty-seven (60%) patients are still disease-free. All disease-free patients were in their first CR. The seven-year estimated survival is 71% and the estimated 7-year progression-free survival (PFS) was 48%. The estimated probability of complete responders to be disease-free at 6 years is 78%. Pretreatment laboratory parameters (serum levels of thymidine kinase, LDH and TNF-alpha showed a good prognostic relevance at using univariate analysis. At multivariate analysis, only the pretreatment serum levels of TNF-alpha were significantly associated with a higher CR achievement probability (p = 0.02) and a longer PFS (p = 0.02). We established a risk model for clinical outcome based on these 3 parameters. Patients having all parameters within the normal range at diagnosis, showed a very good prognosis (100% 7-year PFS and survival), while patients with all parameters increased had a very poor prognosis (0% 7-year PFS and 22% 7-year survival). In conclusion, COA treatment appears to be a non-toxic and very effective treatment for low-grade non-Hodgkin's lymphomas.(ABSTRACT TRUNCATED AT 250 WORDS)