Hypercalcemia in Cancer: Association with Malignancy Type and Effect on Mortality

Abstract

Purpose Hypercalcemia is an electrolyte disorder found in cancer patients which can complicate the disease and hasten death. It is classified by a blood serum calcium level of 2.6 mmol/l and above and its incidence is related to malignancy type. The object of this study is to explore the distribution of hypercalcemia amongst different cancer forms and to record the effects on mortality. The study investigates the same factors with regards to moderate and severe hypercalcemia. Methods Medical records for 2048 patients admitted over a five year period (2008-12) to the National Centre for Cancer Care, Qatar, were retrospectively reviewed to establish calcium levels. Results Chi-square distinguished multiple myeloma, renal cell carcinoma and lung cancer as the most common malignancies associated with hypercalcemia in our sample. The malignancies that most commonly resulted in severe hypercalcemia were multiple myeloma, head and neck and renal cell carcinoma. Univariate analysis identified hypercalcemia, age, and gender and cancer type as predictive factors for survival over the period of the study. These factors were used to build a multivariate model which revealed cancer patients with hypercalcemia were three times more likely to die than patients with normal blood calcium levels. Expiry was also more probable in those above 65 years of age and unexpectedly, females. Another unanticipated finding was that the effects of moderate and severe hypercalcemia on mortality were similar. Conclusions The present study demonstrated that in a hospitalized cancer population, age, gender, cancer type, and hypercalcemia are prognostic factors for increased mortality. The marginal differences in mortality between those with moderate or severe hypercalcemia suggest that early detection and treatment of such electrolyte imbalance is warranted regardless of calcium severity.