title: Sunitinib causes macrocytosis in patients with advanced renal cell carcinoma.
abstract: BACKGROUND
  Sunitinib is approved for treatment of advanced renal cell carcinoma (RCC). Based on a clinical observation that patients receiving sunitinib developed macrocytosis, we undertook a study to further define this observation.
  
  
  METHODS
  In a retrospective review of RCC patients treated at a single centre, data on treatment duration, hematology parameters, concomitant medications, vitamin B₁₂and folate levels, and thyroid function were recorded.
  
  
  RESULTS
  The 43 patients reviewed had received a median of 5 cycles of sunitinib. Overall, 21 patients (49%) developed macrocytosis after a median of 3 cycles. Of the 9 patients that received 2 or fewer cycles, none developed macrocytosis. Among patients with macrocytosis, 9 (43%) had anemia at the time macrocytosis was first documented. In patients who did not develop macrocytosis, 82% showed a trend of increasing mean corpuscular volume.
  
  
  CONCLUSIONS
  Treatment with sunitinib in patients with RCC can cause macrocytosis. The frequency of macrocytosis increases with duration of treatment. The mechanism of sunitinib-associated macrocytosis remains to be elucidated.
authors.affiliation: Department of Oncology, Cross Cancer Institute, 11560 University Avenue, Edmonton, AB.
authors.forename: J
authors.initials: J
authors.lastname: Price
authors.forename: R
authors.initials: R
authors.lastname: Shaarbaf
authors.forename: L
authors.initials: L
authors.lastname: Wood
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