ABSTRACT: Background/Aims Chemotherapy-related toxicity, while a major focus of randomized clinical trials, has been understudied in population-based research. Eight Cancer Research Network (CRN) sites used Virtual Data Warehouse (VDW) data to examine the risk of cardiotoxicity following chemotherapy for invasive breast cancer. However, information on VDW chemotherapy data validity is limited. This study assessed the validity of VDW data related to the reception and dosages of cardiotoxic chemotherapeutic agents among breast cancer (BC) patients. Methods This was a retrospective, cohort study of women =18 years diagnosed with incident, invasive BC between January 1999 and December 2007. Pharmacy and procedure chemotherapy data were extracted from each site's administrative databases for up to one year following cancer diagnosis date. Random samples of 50 patients stratified on trastuzumab, anthracyclines, and no chemotherapy exposure were selected from each CRN site for detailed medical chart abstraction. We calculated weighted sensitivities and specificities (and 95% confidence intervals [CI]) of using administrative data to accurately capture chemotherapy treatment compared to medical records. Median cumulative doses calculated from administrative data were compared to median doses obtained from the medical chart using the Spearman's correlation coefficient. Results The total cohort included 13,497 BC patients. Patients in the random sample (n=400) had a mean age of 65 (±14) years and were primarily white with most tumors diagnosed at AJCC stage 1 or 2. From the sample, 20% (80/400), 38% (152/400), and 40% (158/400) of patients had VDW exposure to trastuzumab, an anthracycline, and any type chemotherapy, respectively. Trastuzumab, anthracycline, and any chemotherapy sensitivities were 97% (CI=94%-98%), 97% (CI=93%-98%), and 99% (CI=97%-99%), respectively; and specificities were 99% (CI=98%-100%), 99% (CI=96%-99%), and 86% (CI=79%-91%), respectively. Median doses for trastuzumab and anthracyclines from administrative data were 227 mgs and 420 mgs, respectively, while median doses from the medical chart were 2370 mgs and 416 mgs, respectively (r=0.60, p<0.001 and r=0.23, p=0.030, respectively). Conclusions Sensitivities and specificities for CRN chemotherapy administrative data were high and dosages were correlated moderately with chart information. These findings support the use of CRN data in evaluating chemotherapy exposures and related outcomes.
Clinical Medicine & Research 11/2011; 9(3-4):146.