Study: Breast Ca Patients Need Better Cardiac Monitoring

Breast cancer patients received suboptimal cardiac monitoring during treatment with trastuzumab (Herceptin), according to a large population-based study.

Among more than 2,000 patients, only 36% of evaluable participants received adequate monitoring for cardiotoxicity in accordance with current guidelines, reported Mariana Chavez-MacGregor, MD, of the MD Anderson Cancer Center in Houston, and colleagues.

Interestingly, physician characteristics had more influence than patient factors on cardiac monitoring, they wrote in the Journal of Clinical Oncology

"We suspected that the rates of cardiac monitoring were going to be low, but we were surprised on how low, particularly in this high-risk group of patients," Chavez-MacGregor, a medical oncologist, told MedPage Today in a separate interview. "Of particular concern was that even among patients with cardiac comorbidities the rates of cardiac monitoring were not higher."

Specifically, female sex and graduating with a medical degree after 1990 were associated with an increased likelihood of adequate cardiac monitoring. "It is possible that younger graduates are more familiar with the use of trastuzumab, its side effects, and the current guidelines," said Chavez-MacGregor. "It was surprising, however, to see a gender difference."

Because trastuzumab-related cardiotoxicity is reversible, efforts to improve the adequacy of cardiac monitoring are needed, particularly in a vulnerable population," the authors wrote, adding that adequate monitoring among these patients should be considered a marker of quality of care. Disseminating current guidelines should be a priority for hospitals, training programs, and medical societies, they added.

"In terms of trends, probably the more reassuring finding is that the rates of adequate cardiac monitoring are improving with time, suggesting that, as providers, we are becoming more aware of the current guidelines and recommendations," Chavez-MacGregor said. "But all changes in patterns of care take time."

They used the Surveillance, Epidemiology, and End Results, the Medicare and the Texas Cancer Registry, and Medicare-linked databases, to identify 82,751 patients, ages 66 and older, diagnosed with nonmetastatic breast cancer from 2005 to 2009. The study-eligible cohort was narrowed to a much smaller cohort of 2,203 stage I-III patients with full Medicare coverage who received adjuvant trastuzumab-based chemotherapy.

According to the manufacturer's insert, patients on trastuzumab therapy need to have baseline cardiac assessment and frequent subsequent cardiac monitoring.

Baseline cardiac evaluation was performed in 78.8% of patients, and 68.2% had a test within the first 4 months of therapy. However, subsequent monitoring -- one cardiac evaluation at least every 4 months during therapy -- was performed in only 42.6%. In the entire cohort, only 36% of the patients had guideline-adherent cardiac monitoring according to the definition and current guidelines. Older patients were less likely to receive adequate monitoring (P=0.001).

By multivariable analysis, factors associated with optimal monitoring included a more recent year of diagnosis. Using 2005 as a reference year, the hazards ratios were as follows:

• 2007: HR 1.42 (95% CI 1.07-1.88)
• 2008: HR 1.65 (95% CI 1.21-2.27)
• 2009: HR 1.83 (95% CI 1.32-2.54)

Other predisposing factors were anthracycline use (HR 1.39, 95% CI 1.14-1.71), a female treating physician (HR 1.37, 95% CI 1.10-1.70), and a physician graduating after 1990 (HR 1.66, 95% CI 1.29-2.12).

The presence of cardiac comorbidities was not a determinant. Of the variance in the adequacy of monitoring, 15.3% was attributable to physician factors and 5.2% to measured patient factors.

The study had limitations, including its retrospective nature, the challenges of research based on data from insurance claims, and the relatively small proportion of patients treated with adjuvant chemotherapy -- an example of the undertreatment that is "a well-described phenomenon among the elderly," they wrote.

From the American Heart Association:

• Long-term Cardiovascular Toxicity and Cancer Therapy

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