CORRELATION BETWEEN PRIMARY CHEMO-SENSITIVITY AND RADIATION SENSITIVITY IN A PANEL OF HIGHLY MALIGNANT HUMAN SOFT-TISSUE SARCOMA XENOGRAFTS

Background and purpose: Sensitivity to radiation and sensitivity to cy totoxic drugs have been proposed to be independent properties of tumou r cells. However, very few clinical or experimental studies have teste d this hypothesis. Therefore, we evaluated the response to ionizing ra diation and to four cytotoxic drugs in a panel of 12 human soft tissue sarcoma cell lines using the xenograft system. Material and methods: NMRI-nu/nu nude mice with subcutaneous tumours received at a tumour vo lume of 120-200 mm(3) either single dose, single agent chemotherapy wi th 350 mg/kg ifosfamide, 200 mg/kg dacarbazine, 10 mg/kg doxorubicin, 6.6 mg/kg cisplatin, or 24 Gy local tumour irradiation under acutely h ypoxic conditions from a cobalt-60 source. Tumour response to radiothe rapy and chemotherapy was measured as specific growth delay (SGD). Res ults: A significant correlation was found between SGD after radiothera py and SGD after dacarbazine (P < 0.001) and doxorubicin (P = 0.05), w hereas no correlation could be demonstrated for cisplatin. For ifosfam ide, the correlation reached borderline significance. The maximal resp onse to any of the four tested chemotherapeutic drugs correlated very well with the response to radiotherapy (P < 0.001). Conclusion: The re sults suggest that radiation sensitivity and chemosensitivity are not independent properties of soft tissue sarcoma cell lines. (C) 1997 Els evier Science Ireland Ltd.