ANALYSIS OF P53 GENE DELETIONS IN PATIENTS WITH NON-HODGKINS-LYMPHOMABY DUAL-COLOR FLUORESCENCE IN-SITU HYBRIDIZATION

The most common tumour suppressor gene altered in human cancers is p53 , which is located on the short arm of chromosome 17. Structural abnor malities of the short arm and loss of chromosome 17 have been reported to confer resistance to chemotherapy in patients with non-Hodgkin's l ymphoma (NHL). Therefore we studied the incidence and prognostic value of p53 deletions in patients with NHL by fluorescence in-situ hybridi zation using a 40 kb cosmid probe, Specimens obtained from 79 patients with NHL were studied. 46 patients were untreated, and 33 were previo usly treated. 40 tumours had indolent and 39 had aggressive histologie s, p53 deletions were observed in 14 specimens (18%) in 32-90% of the cells. No statistically significant difference in the incidence of p53 deletion was observed between indolent and aggressive NHLs or between untreated and previously treated patients. However, p53 deletions wer e observed in three of four patients with transformed lymphoma. In the untreated patients, p53 deletion had no effect on response to therapy , time to treatment failure, or survival. We conclude that p53 deletio ns are uncommon in NHL, and may be frequent in patients with transform ed lymphoma. In this study, p53 deletions did not influence treatment outcome or prognosis of NHL. Because monosomy 17 and 17p abnormalities have been reported to confer poor prognosis in NHL, other tumour supp ressor genes on 17p should therefore be studied.