Expression of CD44 by rhabdomyosarcoma: a new prognostic marker?

The expression pattern of CD44 standard and variant isoforms are prognostic ally significant in a number of malignancies, The aim of this study was to evaluate the role of the standard isoform of CD44 in predicting the clinica l behaviour of rhabdomyosarcoma. Immunohistochemical analysis of CD44 was u ndertaken using a panel of antibodies recognizing the three core domains of the CD44 molecule. Labelling was repeated in triplicate and reported blind with respect to histological type and outcome. Tumours were characterized as positive in more than 60% of tumour cells labelled and negative ii less than 40% of tumour cells labelled. Tumours with 40-60% of tumour cells labe lling were considered indeterminate. Eleven of 20 favourable histology tumo urs were positive for CD44 compared with one of seven unfavourable tumours (P = 0.07). Eleven of 12 patients with CD44-positive tumours are alive in f irst remission compared with five of 15 CD44-negative tumours (P = 0.001). Expression of CD44 correlates directly with prognosis; however, larger stud ies are required so that multivariate analysis can be undertaken.