Flare hypercalcemia after letrozole in a patient with liver metastasis from breast cancer: a case report

Abstract

IntroductionTamoxifen may occasionally precipitate serious and potentially life-threatening hypercalcemia. However, to date, this has not been documented with aromatase inhibitors.Case presentationA 65-year-old Japanese woman with liver metastasis from breast cancer was admitted to our hospital with vomiting, anorexia, fatigue, arthralgia, muscle pain and dehydration. She had started a course of letrozole five weeks earlier. Our patient's calcium level was 11.6 mg/dL. She was rehydrated and elcatonin was administered. Our patient's parathyroid hormone and parathyroid hormone-related protein levels were not increased and a bone scintigram revealed no evidence of skeletal metastasis. After our patient's serum calcium level returned to within the normal range, letrozole was restarted at one-half of the previous dose (1.25 mg). There were no episodes of hypercalcemia. However, 84 days after restarting letrozole, our patient again complained of arthralgia and treatment was changed to toremifene. During these periods, repeated ultrasonograms revealed no progression of liver metastasis.ConclusionTo the best of our knowledge, this is the first case report of flare hypercalcemia after treatment with letrozole in a patient with metastatic breast cancer.

Letrozole Induced Hypercalcemia in a Patient with Breast Cancer

“…To our knowledge, the association of hypercalcemia and letrozole has been previously reported one time [4]. If this occurs, letrozole might be restarted cautiously with therapeutic benefit.…”

“…Malignancy-related hypercalcemia is due to increased osteoclast activities and bone resorption caused by the increased release of various mediators from the tumor or nontumoral host cells [ 1 – 4 ].…”

“…Clinical trials have found that the AIs, unlike the hormone therapy tamoxifen, increase bone fracture risk [ 14 ]. Moreover, flare hypercalcemia has a rapid onset that characteristically occurs within several days of starting therapy; symptoms are usually short-lived and serum calcium levels return to normal when the offering agent is withdrawn [ 4 ]. However, the temporal relation of the onset of hypercalcemia and administration of letrozole may suggest a possible role for the drug.…”

“…We report a case of hypercalcemia that occurred after initiation of letrozole in a patient with breast cancer. To our knowledge, the association of hypercalcemia and letrozole has been previously reported one time [ 4 ]. If this occurs, letrozole might be restarted cautiously with therapeutic benefit.…”

Two cases of treatment with aromatase inhibitors and development of miliary osteoma cutis—Is there an association?

“…Additionally, reports of hypercalcemia have been identified after initiation of the drug. 6 , 7 , 8 In the literature, there are no reports of AIs resulting in development of miliary osteoma cutis.…”