Proliferative activity and number of clonal chromosome aberrations in non-Hodgkin's lymphomas

Thymidine labelling indices (LI) and the number of clonal chromosome aberrations were assessed in fine-needle aspirates from enlarged lymph nodes in 22 patients with non-Hodgkin's lymphoma (NHL). 11 patients had LI greater than 3.0 (median 8.4) and 11 others had LI less than 3.0 (median 1.0). Three categories of chromosome aberration were recorded: normal karyotype, 1-5 aberrations, and greater than or equal to 6 aberrations or multiple complex changes. The distribution of these categories was different among the patients with LI greater than 3.0 compared to those with LI less than 3.0 (p = 0.02). 8 of 11 patients with LI greater than 3.0 had greater than or equal to 6 or complex changes. The corresponding figures for patients with LI less than 3.0 were 2 out of 11. When 16 previously untreated patients were analysed separately, the median number of clonal aberrations was 6.5 in 8 patients with LI greater than 3.0 and 2.5 in 8 others with LI less than 3.0 (p = 0.025). The results suggest that early and spontaneous changes in the genetic material are common in lymphomas with a high proliferative activity. According to previous studies, therapeutic results are especially poor in NHL with high LI. It is proposed that a high proliferative activity of lymphoma cells facilitates an early development of several new mutants and that some of these may be resistant to chemotherapeutic agents.