CARDIAC MONITORING DURING TRASTUZUMAB TREATMENT

Breast cancer patients on adjuvant trastuzumab need cardiac monitoring, but most don't get it, new research suggests.

"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).