Circulating atrial natriuretic peptide plasma levels as a marker for cardiac damage after radiotherapy

To investigate whether plasma concentrations of atrial natriuretic peptide (ANP) could be used to identify patients with radiation mediated cardiac dysfunction.

Circulating levels of ANP were measured in patients who have been irradiated on a large part of the heart (50-80%; Hodgkin's disease) or smaller part of the heart (20-30%; primary breast cancer). C-terminal ANP was determined by radioimmunoassay (RIA) using a commercial kit.

In this study ANP plasma levels of 121 patients (Hodgkin's disease, 73 patients; breast cancer, 48 patients) and 67 controls were examined. ANP plasma levels of both Hodgkin patients (28.8+/-2.2, P=0.003) and breast cancer patients (20.4+/-2.8 ng/l, P=0.01) were significantly elevated when compared to age-matched controls (13.5+/-1.2 ng/l). Both for the Hodgkin (R=0.42, P=0.05) and breast cancer group (R=0.50, P=0.09) a positive relation between ANP plasma values and age was found. However, no clear relation between ANP plasma levels and time post treatment could be demonstrated. Patients with clinical symptoms of cardiovascular disease (n=25) had significantly higher ANP plasma levels (P<0.001) compared to patients in the same treatment group without evidence of cardiac disease (50.2+/-7.5 vs. 23.3+/-1.3 ng/l, P<0.001, and 38.2+/-12.4 vs. 16.3+/-1.6 ng/l, P<0.001, for Hodgkin's disease and breast cancer, respectively). Eight patients suffered from essential hypertension (n=8), whereas the remaining group of 17 patients showed a variety of cardiac disorders (i.e. myocardial infarction, decreasing ventricular function, and atrial fibrillations). In 11 patients cardiac problems were manifest either before or within a few years after mediastinal therapy. In two patients treated for Hodgkin's disease, and in four patients treated for breast cancer cardiac problems became manifest a long time (>10 years) after radiotherapy. Probably in this group of patients cardiac problems are related to the therapy.

The present study indicates that ANP plasma levels could be used to identify patients with radiation induced cardiac dysfunction.