Thallium-201 perfusion scintigraphy in the evaluation of late myocardial damage in left-side breast cancer treated with adjuvant radiotherapy.

Abstract

To evaluate late myocardial damage after adjuvant radiotherapy using a mixed-beam (photons plus electrons) technique to treat the internal mammary lymph nodes in left-side breast cancer. A bicycle ergometer stress test coupled with thallium-201 perfusion scintigraphy and analysis by single-photon computed tomography (CT) was performed on 19 patients treated with left-side breast/chest wall and internal mammary radiation for breast cancer between 1987 and 1993. To be sure that we would evaluate late toxicity caused by the irradiation, patients had to fulfill the following eligibility criteria: left-side breast cancer, treatment between 1987 and 1993 and no recurrence during follow-up, age < or = 75 years, no known risk for coronary artery disease, no previous chemotherapy, internal mammary field treated with an association of photons and electrons, and CT scan-based treatment planning. Median age at scintigraphy was 59 years. Two patients did not reach optimal exercise level and were not evaluable. Among the 17 evaluable patients representing 91.6 patient years of follow-up, there were no perfusion defects by visual or quantitative analysis. The mixed-beam technique seemed to spare the heart from harmful irradiation and to protect the myocardium. Results need to be confirmed on the long-term use of this technique.