Summary In a phase I study of weekly administered cisplatin combined with oral etoposide, we observed a partial response in 4 out of 11 patients with metastatic colorectal cancer. Subsequently, we performed a phase II study to investigate the activity of this combination as first-line treatment in this disease. Fourteen patients with metastatic colorectal cancer were enrolled in this study. The poor prognosis for numerous patients with metastatic colorectal cancer is an incentive for oncologists to explore new treatments for this disease. The combination of fluorouracil with leucovorin is nowadays the more or less accepted standard treatment, but the optimum treatment schedule still has to be defined (Moertel, 1994). Cisplatin as a single agent at standard doses is inactive in colorectal cancer (DeSimone et al., 1986) but in combination with fluorouracil a modest activity has been reported (Posner et al., 1987; LoRuss et al., 1989;Kemeny et al., 1990). Etoposide as a single agent given intravenously is inactive in colorectal cancer (Perry et al., 1976;Douglass et al., 1979). As colorectal tumours are in general slow growing, a more prolonged administration of cytotoxic drugs may be advantageous. Oral etoposide can be given over a long period of time with acceptable toxicity (Greco et al., 1990). Activity of oral etoposide has been shown in small-cell and non-small-cell lung cancer, germ cell tumours and breast cancer. In a phase I study of weekly cisplatin combined with oral etoposide a partial response was observed in 4 out of 11 patients with metastatic colorectal cancer, most of them pretreated with fluorouracil (Planting et al., 1995 During treatment patients had weekly physical examinations and assessment of toxicity, weekly full blood counts and estimation of electrolytes, calcium and magnesium and creatinine clearance. Neurological examination including VPT was repeated after the cisplatin treatment period. Response to treatment was assessed 2 weeks after the last cisplatin administration. The standard WHO criteria were used for evaluation of response and toxicity (WHO, 1979).
Treatment ScheduleCisplatin was administered at a dose of 70 mg m-2 on days 1, 8 and 15 and days 29, 36 and 43; oral etoposide was administered at a dose of 50 mg daily on days 1 -15 and days 29 -43. During cisplatin administration patients were hospitalised for 24 h. The treatment regimen consisted of prehydration with 1000 ml dextrose saline + 20 mmol potassium chloride + 1 g magnesium sulphate over 4 h; cisplatin powder was dissolved in 250 ml 3% sodium chloride and administered over 3 h followed by post-hydration with 2 1 of dextrose saline + 40 mmol potassium chloride + 2 g magnesium sulphate over 8 h. The anti-emetic regimen consisted of 8 mg ondansetron slow i.v. bolus directly before the start of the cisplatin infusion and was repeated if necessary.In this study dose reductions were not allowed. If at the day of planned cisplatin administration WBC was <2.5 x 109 1-1 and/or platelets were <75 x 109 -1 treatment was postpone...