Cisplatin chemotherapy of ovarian cancer: is short-term in vitro chemosensitivity predictive of long-term patient survival?

The in vitro response to cis-diamminodichloroplatinum (cisplatin) in primary culture of tumour samples obtained at surgery was studied in 61 patients with Stage III ovarian cancer who were also treated with cisplatin. The drug-induced inhibitory effect on cell proliferation (measured by 3H-thymidine incorporation) and metabolism (by 3H-uridine incorporation) was assessed over a 3-hour incubation. At greater than or equal to 20% level of inhibition, the true prediction rate of survival by the proliferative assay was 72% among those with 'sensitive' tumours and of mortality was 66% among those with 'resistant' tumours; at greater than or equal to 50% level of inhibition, the prediction rate of survival by the proliferative assay increased to 88% but that of mortality decreased to 58%. The results with the metabolic assay were comparatively lower at all levels. When the amount of residual disease was taken into the determination of mortality rate, significant differences were found between 'sensitive' and 'resistant' tumours as defined by the proliferative assay in patients with no/minimal disease. The pattern of survival differed significantly between 3 subgroups of tumours, as defined by their responses to cisplatin in the proliferative and metabolic assays -- the best survival was obtained in patients whose tumours were 'sensitive' in both assays.