Hypercalcemia-leukocytosis syndrome associated with lung cancer

Hypercalcemia and leukocytosis are two of the most common paraneoplastic syndromes associated with various malignancies. Of note, concomitant manifestation of hypercalcemia and leukocytosis are occasionally observed in the same cancer patients. However, the relationship between these two paraneoplastic syndromes and clinical outcome is unclear. In the present study, we retrospectively investigated the occurrence of hypercalcemia (> or = 10.2 mg/dl after adjustment for serum albumin concentration), leukocytosis (> or = 14,000/mm3 with no evidence of infection) or both in lung cancer patients (1149 cases). There were 65 cases (5.7%) of hypercalcemia, 16 cases (1.4%) of leukocytosis and six cases (0.5%) of both hypercalcemia and leukocytosis at the time of first presentation. The occurrence of these two distinct paraneoplastic syndromes in the same patients was more frequent than could have been expected by chance alone (P < 0.001). There was a significant correlation between the hypercalcemia-leukocytosis syndrome and performance status (P = 0.002). Survivals of patients with hypercalcemia alone (median survival time: MST 3.8 months, n = 59), leukocytosis alone (MST 1.9 months, n = 10), and the hypercalcemia-leukocytosis syndrome (MST 1.5 months, n = 6) were significantly shorter than those without them (MST 9.5 months, n = 1074; P < 0.001). Moreover, survival of patients with the hypercalcemia-leukocytosis syndrome was significantly shorter than that of patients with hypercalcemia alone (P = 0.013). On the other hand, there was no significant difference in survival between the hypercalcemia-leukocytosis syndrome and leukocytosis alone (P = 0.47). Multivariate analysis of prognostic factors using the Cox proportional hazards model could not demonstrate that the hypercalcemia-leukocytosis syndrome had independent prognostic significance. In conclusion, our results suggest that the hypercalcemia-leukocytosis syndrome is an additional clinical entity of paraneoplastic syndrome and is an indicator for poorer outcome in lung cancer patients, although the frequency of the combined syndrome is very rare (0.5% of cases over a 10 year interval.