title: Evaluation of vitamin D deficiency in breast cancer patients on bisphosphonates.
abstract: BACKGROUND
  Bisphosphonates are very effective in treating osteoporosis and metastatic bone disease; however, unfavorable outcomes can occur when they are given to patients with occult vitamin D deficiency. No clear consensus exists on the assessment of vitamin D status in cancer patients undergoing bisphosphonate therapy. This study examines the prevalence of vitamin D deficiency among breast cancer patients treated with bisphosphonates for osteoporosis or metastatic bone disease, and observes the use of calcium and vitamin D supplementation in these patients.
  
  
  METHODS
  This retrospective study reviewed the electronic records of 321 breast cancer patients treated with bisphosphonates. Information on age, race, and serum levels of 25-hydroxyvitamin D (25-OHD), parathyroid hormone, and calcium were collected, and intakes of calcium and vitamin D supplements were queried in an outpatient pharmacy database.
  
  
  RESULTS
  Of the 321 patients treated with bisphosphonates, 209 (65.1%) had their 25-OHD levels checked at least once. Of these patients, 57 (27.3%) had a serum 25-OHD level <20 ng/ml. Of the 209 patients with a known 25-OHD level, only eight (3.8%) received >600 IU of vitamin D per day, and 41 (19.6%) patients received 400-600 IU of vitamin D daily.
  
  
  CONCLUSIONS
  Especially in the setting of metastatic bone disease in breast cancer patients, we advocate routine 25-OHD concentration screening for vitamin D deficiency in general. Clear guidelines for the diagnosis of vitamin D deficiency in cancer patients would be extremely beneficial to have, as would identification of the proper dose of vitamin D supplementation. We recommend 1,000 IU daily to our metastatic cancer patients.
authors.affiliation: Division of Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Wang-Gillam
authors.forename: Dorothy A
authors.initials: DA
authors.lastname: Miles
authors.forename: Laura F
authors.initials: LF
authors.lastname: Hutchins
mesh_terms: D050071:Bone Density Conservation Agents / Q000009:adverse effects*; D001943:Breast Neoplasms / Q000150:complications*; D015331:Cohort Studies; D004164:Diphosphonates / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006996:Hypocalcemia / Q000139:chemically induced / Q000517:prevention & control*; D012189:Retrospective Studies; D014807:Vitamin D / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology*
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D014807:Vitamin D