PARANEOPLASTIC ELEVATION OF SERUM ALKALINE-PHOSPHATASE IN RENAL-CELL CARCINOMA - INCIDENCE AND IMPLICATION ON PROGNOSIS

Purpose: We investigated the incidence and. prognostic significance of paraneoplastic elevation of serum alkaline phosphatase in patients wi th renal cell carcinoma. Materials and Methods: Clinical data of 365 p athologically proved renal cell carcinoma cases were reviewed. Serum a lkaline phosphatase level greater than 100 units per 1., but without o bvious conditions that may cause phosphatase elevation, including meta stasis to or disease of liver or bone and pregnancy, was regarded as p araneoplastic serum alkaline phosphatase elevation. Survival was evalu ated using the Kaplan-Meier method. Results: Of 365 patients 77 (21.1% ) had paraneoplastic serum alkaline phosphatase elevation. The respect ive incidence from stage I to TV cases was 9.9% (16 of 161), 31,9% (15 of 47), 34.3% (23 of 67) and 25.6% (23 of 90). Patients with stage I disease had the lowest incidence but there were no statistically signi ficant differences among stages II, III and IV disease. Of 77 patients with elevated serum alkaline phosphatase 48 had additional paraneopla stic manifestations. The disease specific 5-year survival rate in pati ents with normal serum alkaline phosphatase was significantly better t han in patients with isolated phosphatase elevation, which in turn was better than in patients with multiple paraneoplastic syndromes (70.7 versus 50.5 versus 30.8%). Patients with persistent or recurrent eleva tion of serum alkaline phosphatase after radical nephrectomy had metas tatic lesion or local recurrence. In some patients serum alkaline phos phatase returned to normal after nephrectomy but metastasis developed later without recurrent phosphatase elevation, Conclusions: Paraneopla stic serum alkaline phosphatase elevation in renal cell carcinoma pati ents implies an unfavorable prognosis, and additional paraneoplastic s yndromes further worsen the prognosis. Recurrent or persistent serum a lkaline phosphatase elevation after-radical nephrectomy suggests dista nt metastasis or residual tumor. However, the return of serum alkaline phosphatase to normal does not guarantee cure of the disease. Identif ication of paraneoplastic serum alkaline phosphatase elevation is valu able in the prediction of outcome and postoperative followup of renal cell carcinoma patients.