Clinical Characteristics, Causes and Survival in 115 Cancer Patients with Parathyroid Hormone Related Protein-mediated Hypercalcemia

Background The aim of this study is to determine the proportion of cancers presenting with parathyroid hormone (PTH) related protein (PTHrP)-mediated hypercalcemia, examine the clinical and biochemical characteristics, identify predictive factors for survival. And we also compared those characteristics between solid organ and hematologic malignancy groups. Methods Cancer patients with PTHrP-mediated hypercalcemia who were treated at Chonnam National University Hospital in Korea from January 2005 to January 2015 were retrospectively reviewed. Results Of all 115 patients, solid organ malignancies were the most common etiology (98 cases, 85.2%), with squamous cell carcinoma (50 cases, 43.4%), adenocarcinoma (27 cases, 23.4%). Interestingly, hepatocellular carcinoma (HCC; 18 cases, 15.7%) and cholangiocarcinoma (11 cases, 9.6%) were much more common causes than other previous reports. Hematologic malignancy was less common (17 cases, 14.8%), with multiple myeloma (9 cases, 7.8%) and non-Hodgkin's lymphoma (5 cases, 4.3%). Overall median survival was only 37 days. There was significant difference in median survival between two groups (35 days for solid organ malignancy and 72 days for hematologic malignancy; P=0.015). Cox regression analysis identified age, the type of malignancy and the time interval of developing hypercalcemia after cancer diagnosis as independent predictive factors for survival time. Conclusions PTHrP-mediated hypercalcemia was most frequently caused by solid organ malignancy. However, HCC and cholangiocarcinoma were important causes of PTHrP-mediated hypercalcemia may be due to geographic differences in cancer incidence in Korean population. Age, the type of malignancy and the time interval of developing hypercalcemia after cancer diagnosis were independent poor predictive factors for survival time.