Change of creatinine clearance rate in accordance with aging in Japanese patients with head and neck cancer

: Most of the head and neck tumors are squamous cell carcinomas (SCCs), which are relatively sensitive to chemotherapeutic agents. Cis-platinum (CDDP), 5-fluorouracil and taxanes are widely used worldwide for SCCs, and CDDP is the most common agent. Renal toxicity is a well-known adverse effect of CDDP, and adequate pre and post-hydration or combined administration of neutralizing agents is performed during CDDP injection. Before the CDDP administration, we have to evaluate renal function of the patients using creatinine clearance rate (Ccr). In Japan, CDDP at the dose of 60-70 mg/m(2)/day is administered in cases with over 65 ml/min/1.73 m(2) of Ccr, whereas in cases under 60 ml/min/1.73 m(2), we use other drugs, e.g., carboplatin, to prevent the renal dysfunction followed by chemotherapy. In other countries, the dose of CDDP is 70-100 mg/m(2)/day, and the discrepancy is based on the poor renal function of Japanese. We calculated Ccrs of 107 head and neck cancer patients since January, 2004 to August, 2005, and evaluated renal function before any treatment. Ccr was decreased in proportion to aging. At the age of fifties, 43.5% of the patients indicated lower Ccr than 65 ml/min/1.73 m(2): sixties, 45.7%; seventies, 50.0%; and eighties, 85.7%. In the United States, the average glomerular filtration rate of over 70 year-old healthy people is estimated as 75 ml/min/ 1.73 m(2), and it is considered sufficient kidney function for the administration of CDDP at the dose of 70-100 mg/ m(2)/day. The incident rate of end-stage renal disease is 1.3 times higher in the United States than in Japan. The incident rate of diabetes, which is the main cause of renal dysfunction, is almost the same in both countries. Though the reason is unclear, it is the fact that the renal function of Japanese decreases quickly in accordance with aging.