DNA cytometry of osteosarcoma

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Abstract
The relationship between cytochemical features and histomorphology in osteosarcoma, and the clinical significance of DNA content were investigated by microspectrophotometry (MSP) of tissue sections and flow cytophotometry (FCM) of cell suspensions. MSP of tissue sections entails the methodological error of determining the DNA content of sectioned cell nuclei. By analyzing 184 normal mesenchymal cell populations, an upper limit of diploidy (normal DNA content) was deduced. Applying this upper limit for 42 sarcomas, 6 were diploid and 36 hyperploid. Comparative analysis of the same lesions by MSP of imprint preparations and by FCM disclosed complete agreement in ploidy classification (diploid versus hyperploid). Retrospective MSP analysis of bone tumors is often impeded by previous demineralization in acid, which destroys DNA. EDTA as an alternative was found to slightly reduce Feulgen DNA stainability of osteosarcomas, but did not affect tumor ploidy determination. Hence, EDTA offers a means of retaining DNA stainability of bone tumors requiring demineralization. MSP analysis of different histologic areas, and comparative FCM analysis of biopsy and surgical specimens, dislosed that individual osteosarcomas are cytochemically uniform despite morphologic heterogeneity. Hence, a single tumor sample for DNA analysis can be relied upon as representative for the tumor as a whole. In a consecutive series of 83 osteosarcoma patients treated by surgery and adjuvant Interferon, the 7-year survival rate was 0.44. MSP DNA analysis gave no significant prognostic information. Multivariate analysis identified 3 risk factors for tumor related death, i.e., male sex, proximal tumor location, and histologic grade IV. In a prognostication model, the 7-year survival rates, for patients with 0, 1, 2, or 3 risk factors, were 0.80, 0.59, 0.42, and 0.13, respectively. Hence, it is possible to identify subgroups of high grade osteosarcoma patients with different prognosis. In a study of 166 primary bone tumors, the applicability of DNA analysis for differential diagnostic purposes was investigated. The series included high grade osteosarcomas, parosteal osteosarcomas and benign bone tumors, which may be mixed up histologically with osteosarcoma. Out of 166 tumors, 149 (90%) were histologically noncontroversial, whereas 17 (10%) posed diagnostic difficulties. In the diagnostically noncontroversial group, all benign tumors and parosteal osteosarcomas were diploid, whereas 97 of 102 osteosarcomas were hyperploid. Hence, hyperploidy seems to be a characteristic feature of high grade osteosarcoma.(ABSTRACT TRUNCATED AT 400 WORDS)