title: Flare hypercalcemia after letrozole in a patient with liver metastasis from breast cancer: a case report.
abstract: BACKGROUND
  Tamoxifen may occasionally precipitate serious and potentially life-threatening hypercalcemia. However, to date, this has not been documented with aromatase inhibitors.
  
  
  METHODS
  A 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.
  
  
  CONCLUSIONS
  To 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.
authors.affiliation: Department of Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan. kurochan@dd.iij4u.or.jp.
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Kuroi
authors.forename: Toshinari
authors.initials: T
authors.lastname: Yamashita
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Aruga
authors.forename: Kazumi
authors.initials: K
authors.lastname: Horiguchi
authors.forename: Dai
authors.initials: D
authors.lastname: Kitagawa
authors.forename: Susumu
authors.initials: S
authors.lastname: Sekine
authors.forename: Hiromi
authors.initials: H
authors.lastname: Tokita
authors.forename: Yuka
authors.initials: Y
authors.lastname: Hirashima