Retinoblastoma gene product and p21 (WAF1, CIP1) protein expression in nonHodgkin's lymphomas: A multivariate survival analysis

We evaluated immunohistochemically the expression of two negative regulator s of the cell cycle, namely retinoblastoma gene product (pRb) and WAF1/Cip1 gene product (p21), in paraffin sections from 93 patients with non-Hodgkin 's lymphomas (NHL) and related it to clinicopathological parameters, prolif erative fraction, p53 expression and survival. Patients were followed until death (n=33) or for an average of 52 months (60-160). Rb labelling index ( LI) increased with malignancy grade and proliferative activity bur was unre lated to other clinicopathological parameters. In 33% of cases, especially those of the aggressive groups, we observed diminished pRb expression (i.e. low pRb/Ki-67 ratio), p21 expression on the other hand correlated only wit h histological grade. Rb LI and p53 LI. In multivariate analysis, Rb LI was a negative predictor of disease-free survival but was linked to a higher p robability of complete response. However, diminished pRb expression as well as p21 expression were not statistically significant prognostic indicators . Our results suggest that pRb as a cell cycle related molecule may play an important role in determining prognosis and therapeutic response in NHL pa tients.