Parathyroid hormone-related protein and serum calcium in patients with renal cell carcinoma.

OBJECTIVE: To evaluate serum parathyroid hormone-related protein (PTHrP) in relation to serum calcium and clinical outcome of patients with renal cell carcinoma.

METHODS: Sera from 243 patients with renal cell carcinoma were collected prior to therapy. Serum PTHrP was analyzed using an immunoradiometric assay. Tumour stage, nuclear grade, corrected serum calcium, and survival were assessed.

RESULTS: Serum PTHrP was detectable in 37/243 sera (15%) and hypercalcaemia (> or =2.60 mmol/l) in 32/220 (15%). A positive correlation between serum PTHrP and serum calcium was found (r = 0.326; p < 0.01). Following subdivision of the material, based on storage time, the frequency of detectable serum PTHrP seemed to decrease with time. Serum calcium, but not serum PTHrP, was correlated to tumour stage (p < 0.001). Survival was similar for patients with detectable and undetectable PTHrP, but those with hypercalcaemia had a significantly shorter survival time compared to those with normal serum calcium (p < 0.001). A multivariate analysis showed that tumour stage and serum calcium were independent prognostic factors, but not grade or PTHrP.

CONCLUSIONS: A positive relation of serum PTHrP to serum calcium was demonstrated in patients with renal cell carcinoma. Hypercalcaemia but not serum PTHrP predicted a worse prognosis.