Abstract and Introduction
Aims: Trastuzumab, one of the best known examples of personalized medicine, requires regular cardiac monitoring because it can cause heart failure. We aimed to assess the utilization of cardiac monitoring in women with nonmetastatic breast cancer receiving trastuzumab-based chemotherapy in routine clinical practice.
Patients & methods: The medical records of women continuously enrolled in a large national health insurance plan who were diagnosed with nonmetastatic breast cancer and treated with trastuzumab from 2006 to 2008 were reviewed (n = 109). The primary outcome variables were the use and type of cardiac monitoring testing before and during trastuzumab therapy. An exploratory multivariable logistic regression analysis was performed to identify predictors for receiving cardiac monitoring both at baseline and during trastuzumab treatment.
Results: Monitoring both before and during therapy was less common (62%), although 74% had cardiac monitoring before therapy and 80% had at least one test during therapy. Radionuclide ventriculogram was utilized more often than echocardiography (48 vs 42%). Only the use of anthracycline (odds ratio: 2.39; 95% CI: 1.01–5.71) was significantly associated with use of a cardiac monitoring both at baseline and during trastuzumab treatment.
Conclusion: The use of cardiac monitoring testing was variable and opportunities to improve quality and reduce cost are evident. These results have clinical implications for other personalized medicine interventions requiring regular laboratory monitoring.
Trastuzumab is one of the best known examples of personalized medicine. It targets HER-2-positive breast cancer and significantly reduces breast-cancer mortality in women who are HER-2 positive.[1–4] However, this drug can cause left ventricular dysfunction, a potentially serious side effect, by interfering with EGF receptor-2-mediated cell signaling, an important pathway for growth and protection of cardiomyocytes.[1–5] About 10% of trastuzumab recipients show a decline in left ventricular ejection fraction (LVEF) and 1–4% develop symptoms of systolic heart failure.[1–3] While trastuzumab-related left ventricular dysfunction can be reversible or treatable, some patients experience long-term adverse effects from the drug.
Trastuzumab product labeling and professional guidelines recommend monitoring cardiac function before trastuzumab-based therapy in order to avoid use of the drug among patients at elevated cardiac risk, and regularly every 3–4 months during therapy to detect left ventricular dysfunction early with the hope of stopping therapy before it becomes symptomatic.[7,8,101] Both radionuclide ventriculography (RVG; also known as multigated acquisition scan or MUGA scan) and echocardiography are commonly used to monitor left ventricular function. RVG has a high reproducibility and low intra- and inter-observer variability, but it exposes the patient to radiation and is expensive.[9,10] Echocardiography is easy to perform and does not expose the patient to radiation, but often requires the involvement of a cardiologist. Neither the product labeling nor professional guidelines recommend a specific cardiac monitoring test.
Little is known about the use of cardiac monitoring in routine clinical practice, and more specifically about whether patient, diagnosis or health system factors are associated with the frequency or type of testing. Our objective was to use linked administrative claims and chart review data from a large national health plan to assess the utilization and predictors of cardiac monitoring among women with nonmetastatic breast cancer receiving trastuzumab-based chemotherapy.
Personalized Medicine. 2013;10(7):703-708. © 2013 Future Medicine Ltd.