EW YORK (Reuters Health) Oct 18 - Breast cancer patients treated with trastuzumab are at high risk of congestive heart failure(CHF), particularly if they are older or have cardiac comorbidities, a new study shows.
Researchers found nearly one in three older patients taking trastuzumab developed CHF, which is higher than has been reported in clinical trials. Among non-users, the rate of CHF was less than 20%.
"We by no means want to imply that these patients should not get trastuzumab. Older patients should be getting trastuzumab, which is a wonderful treatment that has dramatically changed breast cancer outcomes," said lead author Dr. Mariana Chavez-MacGregor of the University of Texas MD Anderson Cancer Center in Houston.
"But we can use this information to identify high-risk patients and discuss the risks and benefits of therapy with our patients in a more informative way," she told Reuters Health. "The risk of cardiac problems is higher among them and we as physicians need to be aware of this, individualize our treatment, and balance the risks and benefits."
The findings were published online October 14 in the Journal of Clinical Oncology.
Dr. Chavez-MacGregor and her team used the SEER-Medicare and the Texas Cancer Registry-Medicare databases to identify patients diagnosed with stage I-III breast cancer between 2005 and 2009 and treated with chemotherapy.
"Close to 40% of breast cancer patients are older than 65, but only a fraction of them are represented in clinical trials," she noted. "Most clinical trials work with younger women who are healthier, but we paid particular attention to the high-risk women over 65 with problems including diabetes and hypertension -- the more typical patients we take care of in day-to-day practice."
Of the 9,535 patients in the study, 9,419 were female and 2,203 (23.1%) received trastuzumab; the median age was 71 years.
Among trastuzumab users, the rate of CHF was 29.4% compared to 18.9% among non- users (p<0 .001="" 1.95.="" a="" hazard="" of="" p="" ratio="" yielding="">
Trastuzumab users over 80 were significantly more likely to develop CHF than were younger patients on the drug (HR, 1.53). Other risk factors included coronary artery disease (HR, 1.82), hypertension (HR, 1.24), and weekly trastuzumab administration (HR, 1.33).
The researchers had expected cardiac toxicity rates to be higher than those seen in trials, but the magnitude was a surprise, said Dr. Chavez-MacGregor.
"With our high-risk patients we need to get our cardiology colleagues involved earlier. Most patients have asymptomatic cardiac problems we can find very easily. If we monitor patients appropriately, we can identify trastuzumab cardiac toxicity problems early and help reverse them," she said.
She cautioned that, while doctors can identify risk factors of patients at higher risk, they are still unable to predict who will develop cardiac toxicity. Also, because the study was based on insurance claims, the researchers did not have information about the disease severity and its impact on the patients' quality of life.
SOURCE: http://bit.ly/1aRk23n
J Clin Oncol 2013.
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