DRUG SENSITIVITY OF DIFFERENT TUMOR LESIONS FROM THE SAME PATIENT EVALUATED BY A SHORT-TERM ASSAY

A short-term antimetabolic assay, which considers the interference with [3H]thymidine incorporation as an indicator of drug effect, has been used to comparatively assess the chemosensitivity of different tumor lesions from the same patient. The analysis was performed on primary tumors and their synchronous metastases from 67 patients with breast, ovarian, gastrointestinal and germ cell testicular tumors. A remarkable difference in sensitivity to cytostatic drugs was observed between the two lesions. In contrast, a strong association in chemosensitivity (81.7% agreement rate; p less than 0.01) was observed between two synchronous metastases from 17 patients with breast, ovarian, germ cell testicular tumors or malignant melanoma. In addition, the predictive relevance of the antimetabolic assay on clinical response to chemotherapy was analyzed in relation to the type of tumor lesion tested in vitro in a retrospective correlative study on 57 patients with advanced ovarian and germ cell testicular tumors. The objective clinical response was significantly correlated to the in vitro sensitivity of metastases (83.7% agreement rate; p less than 0.01), but not to that of the primary tumor.