AMSTERDAM (FRONTLINE MEDICAL NEWS) – Breast cancer patients who underwent chemotherapy or radiotherapy had about a two-fold increased prevalence of mild systolic cardiac dysfunction a median of 10 years after treatment, compared with age-matched controls in a study that included a total of 700 people.

But even longer follow-up of treated breast cancer patients is needed to determine whether the excess mild cardiac dysfunction seen in this analysis eventually progresses to more severe cardiac impairment, Liselotte M. Boerman said at the European Breast Cancer Conference.

Data from the Breast Cancer Long-term Outcome of Cardiac Dysfunction ( BLOC ) study showed that 175 breast cancer patients who received chemotherapy (and may have also received radiotherapy) had a 2.5-fold higher prevalence of a left ventricular ejection fraction (LVEF) below 54% (95% confidence interval, 1.2-5.4) when measured by echocardiography a median of 10 years after treatment, compared with an equal number of age-matched individuals from the general population.

A separate group of 175 patients treated with radiotherapy only and evaluated by echocardiography a median of 10 years later had a 2.3-fold increased prevalence (1.1-4.7) of a LVEF below 54% when compared with an equal number of age-matched individuals, said Ms. Boerman, an epidemiology researcher at the University of Groningen (the Netherlands).

This degree of left-ventricular dysfunction was found in 15% of the chemotherapy patients and 6% of their controls, and in 16% of the radiotherapy patients and 8% of their controls.

However, the treated breast cancer patients had no long-term increase in their prevalence of more significant systolic cardiac dysfunction, defined as a LVEF of less than 45%, compared with the controls, and the overall rate of systolic dysfunction of this severity was low, affecting fewer than 1% of patients.

Also, the chemotherapy and radiotherapy patients showed no significant increase in the prevalence of diastolic cardiac dysfunction, defined as delayed cardiac relaxation beyond the age-appropriate range. Treated patients did show, after 10 years, a suggestion of an increased prevalence of diagnosed cardiovascular disease, which was 2.3-fold higher (1.0-4.9) in the chemotherapy-receiving patients, compared with their controls; and 70% higher (0.9-3.4) among the patients treated with radiotherapy, compared with their controls, Ms. Boerman said.

The study used data collected from breast cancer patients younger than 80 years old treated after 1980 and controls seen by general practice Dutch physicians. The chemotherapy patients were diagnosed at an average age of 49 years old (range 26-66 years old). About 78% had received treatment with an anthracycline agent and 7% had received trastuzumab (Herceptin). Radiotherapy had also been administered to 70%, while 62% had also received hormonal therapy, and 7% either had a recurrence or developed a tumor in their contralateral breast.

None of the radiotherapy-only patients had received chemotherapy, but 21% had also received hormonal therapy. Their average age at diagnosis was 54 years old (range 32-79 years old), and 10% had a recurrence or a contralateral tumor.

Follow-up echocardiography occurred 5-34 years after the index treatment, at a median age of 60 years old. Echocardiography follow-up occurred in 70% of the chemotherapy breast cancer patients contacted, and in 63% of those who received radiotherapy only. Among controls, about half of those selected by age matching, and contacted, agreed to participate.

Rates of cardiovascular-disease risk factors – dyslipidemia, hypertension, and diabetes – were at roughly similar levels in the cases and controls at the time of breast cancer diagnosis. But the rate of current smoking at the time of diagnosis appeared higher in the cases (30% among those who received chemotherapy and 33% among those on radiotherapy), compared with their respective control groups (22% and 30%). Ms. Boerman said that a multivariate analysis had not yet been run on the data but should occur soon.

“The prevalence of cardiac dysfunction was higher [in treated patients] than I would have expected, but there is potential bias as only 70% of invited patients actually participated,” commented Dr. Robert Mansel , a professor at the Institute of Cancer & Genetics at Cardiff University (Wales). He also noted the very low rate of patients who developed severe cardiac dysfunction.

Ms. Boerman and Dr. Mansel reported having no financial disclosures.

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