Drug monitoring during FOLFOX6 therapy in a rectal cancer patient on chronic hemodialysis.

Long-term hemodialysis is considered to be a significant risk factor for cancer, but little is known about the use of oxaliplatin in patients on chronic hemodialysis. A 58-year-old man on chronic hemodialysis was treated for unresectable rectal cancer with synchronous hepatic metastasis by FOLFOX6 therapy with therapeutic drug monitoring. Plasma levels of total platinum, ultrafiltrate (free) platinum and 5-fluorouracil were monitored from the start of oxaliplatin administration to 120 h after the end of oxaliplatin infusion. Pharmacokinetic data of free platinum showed a bimodal pattern, decreased rapidly during the first dialysis and subsequently rose until 48 h after oxaliplatin infusion. The free platinum area under the curve was 15.7-18.9 microg h/ml when 40 mg/m(2) of oxaliplatin was administered, which was comparable to the area under the curve at 85 mg/m(2) in patient with normal renal function. The total platinum level reached a peak immediately before dialysis and gradually decreased. The 5-fluorouracil level decreased rapidly after the start of dialysis and remained constant during the continuous infusion of 5-fluorouracil. Tumor response was judged to be stable disease for >6 months, and no peripheral neuropathy or other toxicity was observed even after 11 courses. FOLFOX6 therapy with reduced dose of oxaliplatin had been safely performed for >6 months without any severe toxicity. The serum levels of free platinum showed bimodal pattern, and this second peak increased the area under the curve of free platinum. This pattern seems to be unique in patients on hemodialysis.