"We suspected that the rates of cardiac monitoring were going to be low,
but we were surprised at how low the rates were, particularly in this
high-risk group of patients. Of particular concern was that, even among
patients with cardiac comorbidities, the rates of cardiac monitoring
were not higher," lead author Dr. Mariana Chavez-MacGregor, assistant
professor of Cancer Prevention at the University of Texas MD Anderson
Cancer Center in Houston, told Reuters Health by email.
Physician characteristics may have greater influence than patient
factors on the adequacy of cardiac monitoring, the authors wrote online
May 11 in the Journal of Clinical Oncology.
Dr. Chavez-MacGregor and colleagues extracted Medicare-linked data from
the Surveillance, Epidemiology, and End Results (SEER) database and the
Texas Cancer Registry (TCR) to examine the patterns and adequacy of
cardiac monitoring and to evaluate factors associated with adequate
monitoring.
According to the authors, "Cardiac monitoring with echocardiogram or
radionuclide ventriculography (multiple-gated acquisition scans) is part
of the standard of care among patients receiving trastuzumab-based
chemotherapy. The National Comprehensive Cancer Network guidelines
recommend cardiac monitoring at baseline and at 3, 6, and 9 months after
initiating trastuzumab therapy."
They identified 2,203 patients age 66 or older, with a median age of 72,
who had full Medicare coverage and had been diagnosed with stage I to
III breast cancer between 2005 and 2009 and treated with trastuzumab.
Only 793 (36.0%) of the patients were adequately monitored.
Patients who received optimal cardiac monitoring were more likely to
have a more recent year of diagnosis (hazard ratio 1.83), a physician
graduating after 1990 (HR, 1.66), a female prescribing physician (HR
1.37), and anthracycline use (HR 1.39).
Patients with cardiac comorbidities were not more likely to receive adequate cardiac monitoring.
Overall, 15.3% of the variance in the adequacy of cardiac monitoring was
attributable to physician factors and 5.2% to patient factors.
"I think that our findings can create awareness among oncologists and
hopefully impact the practice of oncologists by improving the rates of
cardiac monitoring," Dr. Chavez-MacGregor wrote in an email.
Dr. Tracey O'Connor, associate professor of oncology at Roswell Park
Cancer Institute in Buffalo, New York, told Reuters Health by email, "At
36%, the rates of optimal cardiac monitoring in this interesting study
were surprisingly low, given the ready availability of guidelines to
shape medical practice, and the knowledge that older patients are
particularly likely to develop cardiac toxicity, making monitoring
critical."
"Cardiac monitoring is especially important in elderly patients, who
have more preceding cardiac history and are at higher risk for
developing cardiac problems from trastuzumab," advised Dr. O'Connor, who
was not involved in the study.
Dr. Susmita Parashar, director of the Winship at Emory Cardio-Oncology
Program of Emory University in Atlanta, Georgia, said by phone, "These
findings that only about one-third of these patients received adequate
monitoring are alarming. It is disappointing that the quality of care is
so low, but it does not surprise me because in a similar study, we
found that only about one-third of lymphoma patients had adequate
cardiac monitoring."
"Breast cancer patients taking trastuzumab may have decreased ejection
fraction. If we don't follow up with these patients, they may have heart
failure," cautioned Dr. Parashar, who was not involved in the study.
"Early detection and monitoring can prevent further progression. It's
very important to monitor these patients so we can detect early
subclinical heart disease and prevent heart failure," she added.
The authors acknowledged that they were limited by the retrospective
nature of the data and the characteristics inherent in claims-based
research.
Dr. Chavez-MacGregor called for further research "to determine what is
the optimal/needed time interval to perform tests and whether any other
tests (echocardiogram with strain for example) might be better to detect
early cardiac dysfunction.
Dr. Chavez-MacGregor has received financial support from Roche, the
parent company of Genentech, the maker of Herceptin (trastuzumab).
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