Incidental Findings on Simulation CT Images for Adjuvant Radiotherapy in Breast Cancer Patients

We designed this study to evaluate the incidence of incidental findings on computed tomography (CT) scan implemented as simulation for adjuvant radiotherapy in breast cancer patients and to emphasize the need for careful review of simulation CT images before planning radiotherapy. A Resident and attending radiation oncologists retrospectively reviewed the medical records and simulation CT images of 776 patients treated with adjuvant radiotherapy at Samsung Medical Center during 2008. Previously undetected abnormal findings on simulation CT images were defined as incidental findings and interpreted by diagnostic radiologist. If the incidental findings required further evaluation or follow-up, they were defined as indeterminate findings. If subsequent cancers were diagnosed according incidental findings, they were defined as malignancy-related findings. There were 81 indeterminate findings (10.8%) including thyroid nodule, solitary pulmonary nodule, mediastinal lymph node, supraclavicular or axillary lymph node. Among them, there were nine malignancy-related findings (1.3%), including four thyroid cancers, three lung metastases, one primary lung cancer, and one axillary lymph node recurrence. The incidence of incidental findings in this study was low, but some of the findings were related to malignancy. Radiation oncologists should be alert to incidental findings on simulation CT, and incidental findings should be evaluated by diagnostic radiologists.