title: Cardiac Monitoring During Adjuvant Trastuzumab-Based Chemotherapy Among Older Patients With Breast Cancer.
abstract: OBJECTIVE
  Patients treated with adjuvant trastuzumab require adequate cardiac monitoring. We describe the patterns of cardiac monitoring and evaluate factors associated with adequate monitoring in a large population-based study of older patients with breast cancer.
  
  
  METHODS
  Patients age 66 years or older with full Medicare coverage, diagnosed with stage I to III breast cancer between 2005 and 2009, and treated with adjuvant trastuzumab-based chemotherapy were identified in the SEER-Medicare and the Texas Cancer Registry-Medicare databases. The adequacy of cardiac monitoring was determined. Chemotherapy, trastuzumab use, cardiac monitoring, and comorbidities were identified by using International Classification of Diseases, 9th revision and Healthcare Common Procedure Coding System codes. Prescribing physician characteristics were also evaluated. Analyses included descriptive statistics and multilevel logistic regression models.
  
  
  RESULTS
  In all, 2,203 patients were identified; median age was 72 years. Adequate monitoring was identified in only 36.0% of the patients (n = 793). In the multivariable model, factors associated with optimal cardiac monitoring included a more recent year of diagnosis (hazard ratio [HR], 1.83; 95% CI, 1.32 to 2.54), anthracycline use (HR, 1.39; 95% CI, 1.14 to 1.71), female prescribing physician (HR, 1.37; 95% CI, 1.10 to 1.70), and physician graduating after 1990 (HR, 1.66; 95% CI, 1.29 to 2.12). The presence of cardiac comorbidities was not a determinant for cardiac monitoring. Of the variance in the adequacy of cardiac monitoring, 15.3% was attributable to physician factors and 5.2% to measured patient factors.
  
  
  CONCLUSIONS
  A large proportion of patients had suboptimal cardiac monitoring. Physician characteristics had more influence than measured patient-level factors in the adequacy of cardiac monitoring. Because trastuzumab-related cardiotoxicity is reversible, efforts to improve the adequacy of cardiac monitoring are needed, particularly in vulnerable populations.
authors.affiliation: All authors: The University of Texas MD Anderson Cancer Center, Houston, TX. mchavez1@mdanderson.org.
authors.forename: Mariana
authors.initials: M
authors.lastname: Chavez-MacGregor
authors.affiliation: All authors: The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Jiangong
authors.initials: J
authors.lastname: Niu
authors.affiliation: All authors: The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Ning
authors.initials: N
authors.lastname: Zhang
authors.affiliation: All authors: The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Linda S
authors.initials: LS
authors.lastname: Elting
authors.affiliation: All authors: The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Smith
authors.affiliation: All authors: The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Jose
authors.initials: J
authors.lastname: Banchs
authors.affiliation: All authors: The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Gabriel N
authors.initials: GN
authors.lastname: Hortobagyi
authors.affiliation: All authors: The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Sharon H
authors.initials: SH
authors.lastname: Giordano
mesh_terms: D000368:Aged; D061067:Antibodies, Monoclonal, Humanized / Q000009:adverse effects*; D000970:Antineoplastic Agents / Q000009:adverse effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D017024:Chemotherapy, Adjuvant / Q000009:adverse effects*; D015897:Comorbidity; D016903:Drug Monitoring; D005260:Female; D006331:Heart Diseases / Q000139:chemically induced*; D006334:Heart Function Tests; D006801:Humans; D009367:Neoplasm Staging; D012189:Retrospective Studies; D012307:Risk Factors; D018426:SEER Program; D013781:Texas; D000068878:Trastuzumab
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D000068878:Trastuzumab