Incidence of heart disease and functional significance of changes in the electrocardiogram 10 years after radiotherapy for breast cancer

Abstract

Late cardiac complications after radiotherapy for breast cancer was studied in 197 patients examined before, 6 months after, and 10 years after treatment. The 10-year follow-up was done by survey of the files of patients who had died and re-examination of patients who were alive and free of cancer. Among 95 patients who died, 3 died of cardiopulmonary diseases. Autopsy in 32 patients showed serious cardiac abnormalities in 3. Of 102 patients alive at follow-up, 3 reported heart symptoms. Sixty-nine patients participated in the re-examination. Electrocardiogram (ECG) abnormalities were found in 19% of these patients before treatment; in 45% at 6 months, essentially due to T-wave changes in patients who had received left-sided irradiation; and in 45% at 10 years, with fewer T-wave abnormalities but more ST depression and ectopic beats. Average working capacity was 83 W before, 81 W at 6 months, and 84 W at ten years. Average heart volume was 680 ml before, 689 ml at 6 months, and 718 ml (P < 0.01) 10 years after treatment. In conclusion, there was a high incidence of ECG T-wave changes, but they were reversible, and the perimyoeardil damage indicated was functionally insignificant. The incidence of serious cardiac complications was low.Cancer 57:929-934,1986EVERAL CASE REPORTS on late cardiovascular com-S plications after radiotherapy for various thoracic tumors have been published. Pericardial effusion, constrictive pericarditis, and myocardial fibrosis are most often encountered,' but coronary heart disease has also been reported.2 Reviews of the subject have been p~blished.~" However, there are few reports as to the incidence of longterm cardiac complications in prospective studies of patients given irradiation for breast cancer. Changes in the electrocardiogram (ECG) appearing in connection with radiotherapy for thoracic tumors also have been repeatedlyIn a major series treated for breast cancer, the incidence of T-wave changes was 4% with right-sided and 70% with left-sided treatment.' The prognostic significance of this sign of perimyocardial damage has been studied in small patient groups only, and only for fairly short follow-up periods.'oJ'Radiotherapy reduces the rate of local recurrence in breast cancer,'* and its application is increasing in combination with local excision of small t~m o r s . '~

The potential cardioprotective effects of amifostine in irradiated rats

“…After irradiation, the cardiac rhythm changes are probably due to ischemic fibrosis affecting the conduction system (43). Signs of myocardial cell death appear in the ECG too late to be clinically useful (8,13).…”

Adjuvant Radiotherapy in Breast Cancer: The Treatment of Lymph Node Areas

“…Symptomatic acute pneumonitis is unusual in breast cancer; the occurrence rate should be kept below 1% if an adequate technique is used (77) Moderate radiation doses should be given to a limited part of the heart to decrease complications (80)(81)(82). In the 1980s, it was reported that the use of postoperative radiotherapy was related to electrocardiographic changes (83). In the Oslo trial (47), a direct Co60 beam was used to irradiate the internal mammary chain and the supraclavicular area.…”

The effect of radiotherapy on cardiac function

“…Strender et al found T-wave abnormalities after 6 months. Ten years later, not only were T-waves seen to be normalized but ST segment depression and ectopic beats had disappeared as well [25].…”