'Aggressive' low grade lymphocytic lymphomas can be identified by flow cytometric S-phase determinations.

Forty-five patients with low grade non-Hodgkin's lymphomas were studied with respect to the fraction of S-phase cells in fresh tumour material by flow cytometric analysis. Patients with stage I lymphomas were treated with radiotherapy, patients with stage II-IV lymphomas with Prednimustine (Sterecyt). Patients with lymphocytic lymphomas of CLL type were only treated if they had symptoms. Median S-phase fraction in the samples was 2.0 per cent. A significantly shorter survival was found for patients with lymphocytic lymphomas with S-phase fractions > 2.0 per cent compared with cases showing lower S-phase fractions. No significant difference in survival was found in the subgroups of immunocytic or follicular and follicular/diffuse centroblastic/centrocytic lymphomas. In a Cox multivariate analysis, in which also age, constitutional symptoms, stage and morphology were included, the fraction of S-phase cells was found to be a statistically significant, prognostic parameter for low grade lymphomas, mainly due to the result in the subgroup of lymphocytic lymphomas.