Survival in breast cancer patients after the first episode of hypercalcaemia

Abstract

Objectives. To investigate hypercalcaemia (serum ionized calcium (S- Ca2+) > 1.35 mmol L-1) in breast cancer patients before and after the introduction of bisphosphonates and the effect of disease- and treatment- related factors on survival. Design. Prospective and retrospective registration of covariates. Setting. A department of oncology in a university hospital. Subjects. A consecutive cohort of 212 hypercalcaemic patients never treated with bisphosphonate was identified prospectively (period 1) and 193 patients with metastases were classified into three groups: mild (S-Ca2+ < 1.48; n = 102), moderate (1.48 ≤ S-Ca2+ ≤ 1.60; n = 41), and severe hypercalcaemia (S-Ca2+ > 1.60 mmol L-1; n = 50). Fifty-one patients with severe hypercalcaemia all treated with bisphosphonate except one were identified retrospectively (period 2). Results. For period 1 median survival was 6.7 months. Survival was significantly decreased in the two groups with the highest initial S-Ca2+ (P < 0.0001). Median survival tunes in severely hypercalcaemic patients from periods 1 and 2 were 1.4 (95% confidence interval 0.8-2.1) and 2.2 (95% confidence interval 1.3-3.1) months, respectively. In a Cox model for period 1 significant covariates were: WHO performance, extent of metastases, whether systemic anticancer treatment could be given, and haemoglobin, but not S-Ca2+. Conclusion. Prognosis is poor in hypercalcaemic breast cancer patients with WHO performance 3-4 and advanced metastatic disease when effective systemic treatment can no longer be offered. Bisphosphonate treatment does not seem to improve survival in severe hypercalcaemia. Antihypercalcaemic treatment of mild malignancy- associated hypercalcaemia appears not to be vital. Therapeutic efforts should be aiming at patients with moderate hypercalcaemia.