Cohort Study of Pioglitazone and Cancer Incidence in Patients With Diabetes

  1. Laurel A. Habel, PHD1
  1. 1Division of Research, Kaiser Permanente Northern California, Oakland, California
  2. 2Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, Pennsylvania
  3. 3Center for Education and Research in Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania
  4. 4Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, Pennsylvania
  5. 5Department of Medicine, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania
  1. Corresponding author: Assiamira Ferrara, assiamira.ferrara{at}kp.org.

Abstract

OBJECTIVE To explore whether treatment with pioglitazone was associated with risk of incident cancer at the 10 most common sites (prostate, female breast, lung/bronchus, endometrial, colon, non-Hodgkin lymphoma [NHL], pancreas, kidney/renal pelvis, rectal, and melanoma).

RESEARCH DESIGN AND METHODS A cohort study of 252,467 patients aged ≥40 years from the Kaiser Permanente Northern California Diabetes Registry was conducted. All prescriptions for diabetes medications were identified by pharmacy records. Cox proportional hazards models were used to examine the association between risk of incident cancer and ever use, duration, dose, and time since initiation of pioglitazone (modeled as time-dependent variables).

RESULTS In models adjusted for age, sex, year of cohort entry, race/ethnicity, income, smoking, glycemic control, diabetes duration, creatinine levels, congestive heart failure, and use of other diabetes medications, the hazard ratio (HR) for each cancer associated with ever use of pioglitazone ranged from 0.7 to 1.3, with all 95% CIs including 1.0. There was a suggestion of an increased risk of melanoma (HR 1.3 [95% CI 0.9–2.0]) and NHL (1.3 [1.0–1.8]) and a decreased risk of kidney/renal pelvis cancers (0.7 [0.4–1.1]) associated with ever use of pioglitazone. These associations were unaltered with increasing dose, duration, or time since first use.

CONCLUSIONS We found no clear evidence of an association between use of pioglitazone and risk of the incident cancers examined. Because the maximum duration of follow-up was fewer than 6 years after the initiation of pioglitazone, longer-term studies are needed.

  • Received June 4, 2010.
  • Accepted January 27, 2011.

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