title: Trastuzumab therapy in Australia: which patients with HER2+ metastatic breast cancer are assessed for cardiac function?
abstract: OBJECTIVE
  To manage the potential trastuzumab mediated cardiotoxicity, clinical guidelines recommend pre-treatment cardiac function assessment and 3-monthly reassessment during therapy. This study examined rates of cardiac function assessment and predictors of assessment among patients receiving trastuzumab for HER2+ metastatic breast cancer treatment in routine clinical care.
  
  
  METHODS
  Our cohort comprised 3418 women receiving trastuzumab for HER2+ metastatic breast cancer under Australia's nationally funded Herceptin Program (2001-2010). We examined rates of pre-treatment and during-treatment assessment. We used logistic regression and zero-inflated Poisson regression to examine predictors of pre-treatment and during-treatment assessment respectively.
  
  
  RESULTS
  37.7% of patients were assessed pre-treatment, 50.4% during therapy, and 26.4% both before and during therapy. Among patients assessed for cardiac function, reassessment occurred regularly (median of 3.9 months). History of cardiovascular conditions and prior anthracycline use predicted pre-treatment assessment (OR = 1.32, 95% CI: 1.08-1.61; OR = 1.23, 95% CI: 1.05-1.44 respectively). Concurrent trastuzumab and taxane use, exposure to anthracyclines, and older age predicted during-treatment assessment (IRR = 1.17, 95% CI: 1.06-1.29; IRR = 1.12, 95% CI: 1.02-1.23; and IRR = 1.05, 95% CI: 1.01-1.09 respectively). Patients with multi-morbidities were less likely to receive during-treatment assessment.
  
  
  CONCLUSIONS
  Over the last decade, cardiac function assessment in a large cohort of patients receiving trastuzumab was not consistent with guideline recommendations. The association between cardiac monitoring and risk factors for cardiac dysfunction suggest clinicians are triaging patients prior to implementing cardiac assessment. Efforts are needed to identify barriers to implementing current guidelines for cardiac monitoring in metastatic breast cancer patients undergoing trastuzumab treatment, particularly those with multi-morbidities.
authors.affiliation: Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA 02215, USA. christine_lu@harvardpilgrim.org
authors.forename: Christine Y
authors.initials: CY
authors.lastname: Lu
authors.forename: Preeyaporn
authors.initials: P
authors.lastname: Srasuebkul
authors.forename: Anna K
authors.initials: AK
authors.lastname: Drew
authors.forename: Katie
authors.initials: K
authors.lastname: Chen
authors.forename: Robyn L
authors.initials: RL
authors.lastname: Ward
authors.forename: Sallie-Anne
authors.initials: SA
authors.lastname: Pearson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018943:Anthracyclines / Q000009:adverse effects; D061067:Antibodies, Monoclonal, Humanized / Q000009:adverse effects* / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D001315:Australia; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D015331:Cohort Studies; D005260:Female; D006331:Heart Diseases / Q000139:chemically induced / Q000175:diagnosis*; D006334:Heart Function Tests / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D012959:Socioeconomic Factors; D043823:Taxoids / Q000009:adverse effects; D000068878:Trastuzumab; D055815:Young Adult
chemical_list: D018943:Anthracyclines; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D018719:Erb-b2 Receptor Tyrosine Kinases; D043823:Taxoids; D000068878:Trastuzumab; C508053:ERBB2 protein, human