SUN-798 Hypercalcemia of Malignancy: Hormonal Insights Across Cancer Types

Abstract Disclosure: H. Soe: None. P. Manroa: None. S. Fazeli: None. Introduction: Malignancy-related hypercalcemia has a poor prognosis, and humoral causes can be categorized mainly into parathyroid hormone-related peptide (PTHrP) related, which mimics the effects of parathyroid hormone (PTH), the active form of vitamin D (calcitriol), commonly seen in malignant lymphomas or rarely both. These mechanisms typically require different management approaches. This study evaluates the hormonal profiles of patients with hypercalcemia of malignancy, focusing on elevated PTHrP with or without 1,25-dihydroxyvitamin D (1,25 DHCC) elevation, in different cancer types. Methods: Patients presenting to a single cancer center from January 2001 to January 2025 with hypercalcemia and a confirmed cancer diagnosis were reviewed and those with elevated PTHrP, with or without elevated 1,25 DHCC, were included. Data including age, sex, corrected calcium levels, type of cancers, levels of PTHrP, 1,25 DHCC, PTH, 25 OH vitamin D, and survival information were collected. Kaplan-Meier curves and Pearson-correlation were used for statistical analysis. Results: 221 patients were reviewed, 51 (23%) had dual elevation of PTHrP and 1,25 DHCC (Group 1), while 170 (77%) had elevated PTHrP alone (Group 2). The median age was 64 in Group 1 and 65 years in Group 2, with similar gender distributions (about 52% male in both groups). Median overall survival was 309 days for Group 1 versus 100 days for Group 2, though this difference was not statistically significant (p=0.7401). The highest calcium in Group 1 was 17.48 mg/dL found in a patient with Diffuse Large B-cell lymphoma, while in Group 2 was 20.2 mg/dL in a patient with Acute lymphoblastic leukemia. The most common cancer types associated with dual elevation were hematologic malignancies including Leukemia and lymphomas (41%), followed by various subtypes of squamous cell carcinoma (14%), breast cancer (16%), renal cell carcinoma (10%), ovarian cancer (6%) and others (14%). A positive correlation was seen between PTHrP and calcium levels in Group 2 only. Discussion and conclusion : Our study shows a descriptive analysis of malignancy related hypercalcemia. Although survival differences were not significantly different, the findings underscore the importance of a comprehensive hypercalcemia workup, including PTHrP and 1,25 DHCC levels, to guide management and improve prognostic understanding in malignancy-related hypercalcemia. Presentation: Sunday, July 13, 2025