Association Between Parathyroid Hormone-Related Peptide Levels and Mortality in Patients With Malignancy

Hypercalcemia of malignancy is a risk factor for mortality in patients with malignancies. Although the parathyroid hormone-related protein (PTHrP) secreted by tumor cells induces hypercalcemia, the association between serum PTHrP levels and mortality remains unclear. This study aimed to investigate the association between serum PTHrP levels and mortality in patients with malignancies.

We included patients with hypercalcemia (>10 mg/dL) and elevated PTHrP levels (>1.1 pmol/L) and analyzed mortality (overall survival after cancer diagnosis, PTHrP measurement, and 5-year survival rate). Moreover, using Cox proportional hazard model analysis, we investigated the impact of PTHrP levels on survival prognosis, assessing whether this effect varied depending on calcium concentration.

We analyzed the data of 183 patients. The median PTHrP level, corrected calcium level, and age were 5.5 (3.0-10.6) pmol/L, 12.5 (11.5-13.4) mg/dl, and 70 (61-76) years, respectively. PTHrP was significantly and linearly associated with serum calcium levels (correlation coefficient, 0.06; 95% CI: 0.039-0.081, t: 5.69; P < .001). The group with the highest PTHrP levels had significantly worse survival rates than the group with the lowest PTHrP levels (hazard ratio: 1.68, 95% CI 1.03-2.77, P = .038).

This study showed an association between PTHrP and mortality in patients with malignancy after adjusting for serum calcium levels.