Posters— Diagnostic Imaging/Pathology

BIOLOGICAL CHARACTERISATION OF SOFT TISSUE SARCOMAS

Nielsen MM, Hansen O, Starklint H*, Knoop A, Rose C* (Dept. of Oncology, Odense University Hospital, DK-5000 Odense C, Denmark, *Dept. of Pathology, Vejle Hospital, #Dept. of Oncology, Lund University Hospital, Sweden)

In an effort to identify better prognostic factors concerning patients with soft tissue sarcomas (STS), the importance of specific biological characteristics (changes in tumour suppressor genes, oncogene expression, and growth rate) has been addressed in a num-ber of prognostic studies. Unfortunately, no consensus can be drawn from these studies, mainly due to limited number of studies and lack of proper methodology. Therefore, we decided to study the two suppressor gene products, p53 and the pRb1, the oncogene product mdm2 - all three involved in the cell cycle control- and the proliferation marker MIB1.

Aim: To analyse the prognostic significance of the clinical factors and the markers p53, pRb1, mdm2 and MIB1 in patients with STS. Material: All patients with primary STS of the extremities, trunc, retroperitoneum, and head and neck were recruited from a predefined geographical area during the period 1 January 1970 to 31 December 1994. A total of 383 patients were included, of these 28 patients had metastatic disease, leaving 355 patients available for the survival analysis with a median follow up of 13 years and 9 months; 154 patients had either a relapse or a progression of the tumour. Two hundred and sixteen patients died.

Methods: The clinical data was retrospectively collected by review of medical files. The expression of p53, pRb1, mdm2, and MIB1 in the tumours were detected using immuno-histochemistry. The survival analyses were performed using both univariate and multi-variate methods with overall survival as end-point.

Results: We were able to create a prognostic model based on age at diagnosis, large size, high grade, deep sited tumours, retroperitoneal location which could identify four signi-ficantly different risk groups of patients with localised STS, with four different survival probabilities. The immunohistochemical markers MIB1 and pRb1 had independent prognostic value when adjusted for the effect of the clinical prognosticator, while p53 and mdm2 did not. High expression of MIB1 and pRb1 were correlated to poor prognosis. However, none of the indexes including the immunohistochemical markers predicted patients outcome better than the index including only clinical data.

Conclusion: The already known clinical prognosticators are still considered to be the best variables in predicting overall survival of patients with STS.