Association of long-term exposure to circulating platinum with adverse late effects in testicular cancer survivors.
4528 Background: Successful platinum(Pt)-based chemotherapy for testicular cancer (TC) comes at the price of late cardiovascular morbidity and neurotoxicity. Damage induced by circulating Pt could be an etiological mechanism. We investigated the relation between circulating Pt and late effects. Methods: In 96 consecutive TC patients (med age 29 [17-53] at chemotherapy), 3 serum samples and a 24h-urine sample were collected on several time-points med 5 yrs (1-13) after treatment. Pt concentrations ([Pt]) were measured with a sensitive voltammetric method (Lancet 2000, 355:1075). Measured [Pt] combined with cisplatin dose, age, weight and height were analyzed simultaneously to construct a population pharmacokinetic (PK) model using NONMEM. Based on the PK parameters of each patient, individual [Pt] at 1, 3, 5, 10 yrs after start and AUC were calculated. Cardiovascular status, paresthesia and markers of vascular damage were assessed after a med follow-up (FU) of 9 yrs (3-15). Results: Decay of [Pt] was best described by a two compartment model. Mean terminal T1/2 was 3.7 (±0.3) yrs. At all time-points [Pt] correlated with cisplatin dose and renal function during treatment. [Pt] at 3 yrs correlated with systolic blood pressure (BP) (r=.32, p<0.01) and creatinine clearance (CRCL) (r=-.25, p=0.02) at FU. Patients with increased BP had higher Pt AUCs than patients with normal BP (table). Pt AUCs were higher in patients with paresthesia (table). Conclusions: Known late effects of cisplatin-based chemotherapy such as hypertension and paresthesia are related to higher circulating [Pt]. Long-term exposure to Pt is involved in healthy tissue damage in TC survivors. [Table: see text]