Nearly two-thirds of older women receiving trastuzumab for breast cancer do not get adequate cardiac monitoring, despite the known risks for cardiotoxicity, investigators reported.

Only 36% of 2,203 patients with a median age of 72 years who received trastuzumab (Herceptin)-based adjuvant therapy had adequate cardiac monitoring, based on a review (J. Clin. Oncol 2015 May 11 [doi:10.1200/JCO.2014.58.9465]).

“Our study shows that cardiac monitoring is an area that requires improvement. Actions to increase the rates of cardiac monitoring in this vulnerable population are needed, and adequate cardiac monitoring among trastuzumab-treated patients should be considered a marker of quality of care. Efforts to further disseminate current guidelines should be a priority for our hospitals, training programs, and medical societies,” wrote Dr. Mariana Chavez-MacGregor and colleagues from the University of Texas MD Anderson Cancer Center in Houston.

The authors reviewed Medicare data on patients aged 66 years and older with stage I-III breast cancer treated with trastuzumab-based therapy. They found that 79% of the patients had a baseline cardiac evaluation and that 68% had cardiac tests within 4 months of starting on therapy. Only 43% of patients, however, received subsequent monitoring once every 4 months as recommended in treatment guidelines, and only 36% received optimal monitoring with baseline exam and scheduled follow-up evaluations, the researchers reported.

In multivariable models controlling for demographic/socioeconomic factors (age, race, marital status, education, income, urban/rural residence), clinical stage, comorbidities, and anthracycline and taxane use, factors associated with the likelihood of getting optimal monitoring included more recent year of diagnosis, anthracycline exposure, female prescribing physician, and physician age. Physicians who graduated from medical school after 1990 were significantly more likely to recommend monitoring.

“We estimated the relative contributions of physician and patient-level effects to the variance of the observation; 15.3% of the variance in the adequacy of cardiac monitoring was attributable to physician factors, and only 5.2% of the variance was attributable to measured patient factors,” the authors wrote.

Dr. Chavez-MacGregor disclosed financial relationships with Genomic Health, Roche, and Novartis.