Tumor 'flare' hypercalcemia - An additional indication for bisphosphonates?

The most serious, potentially life-threatening manifestation of 'flare' is hypercalcemia, registered in 4-5% of breast cancer patients with bone metas tases, usually during the first few weeks of tamoxifen treatment. There are no specific treatment recommendations for flare hypercalcemia, except tamo xifen withdrawal. There are no reports on the use of bisphosphonates in the treatment of flare hypercalcemia. Among 87 hypercalcemic patients with met astatic breast cancer observed during a 7-year period, 10 patients had tamo xifen-induced hypercalcemia. Diagnosis of flare hypercalcemia was based on the normal pretreatment values of serum calcium and the development of hype rcalcemia within a maximum of 6 weeks of hormonal drug initiation. The medi an time from hormonal drug initiation to flare hypercalcemia was 14 days, t he median duration 8.5 days, and the median calcium level was 3.09 mmol/l ( range 2.79-4.46 mmol/l). All patients were treated with hydration, and 7 pa tients with calcium levels above 3.0 mmol/l were also treated with disodium pamidronate in various single doses (30-90 mg/24 h). Normocalcemia was ach ieved in all patients, and tamoxifen was continued without relapse of hyper calcemia. Median survival was 177 days ys (range 12-570 days). It seems tha t the use of bisphosphonates in the treatment of flare hypercalcemia could allow safe readministration of tamoxifen and prevent premature and unjustif ied tamoxifen discontinuation. Flare hypercalcemia might represent one more indication for the use of bisphosphonates. Copyright (C) 2001 S. Karger AG , Basel.