Unsuspected abnormalities noted on CT treatment-planning scans obtained for breast and chest wall irradiation

Abstract

Purpose: Three-dimensional treatment planning and CT simulation is widely used for the treatment of a variety of cancers. At the Stanford University Medical Center, a treatment-planning CT scan is obtained before breast irradiation to optimize the dose distribution to the treated breast and to limit radiation to the opposite breast, heart, and lung. In this paper, we review the incidental findings discovered on a careful review of these scans. Methods and Materials: Between 1997 and 1999, 153 patients referred for breast or chest wall radiation therapy underwent a treatment-planning CT scan in our department. The planning scans were extended to include not only the breast, but also the neck, thorax, and liver. A resident and attending radiation oncologist carefully reviewed each scan before approving the treatment plan. Any abnormal findings were reviewed by an attending in the department of radiology, and additional diagnostic imaging or other evaluation was obtained as necessary. Results: One hundred and fifty-three sequential scans were reviewed, and 17 unsuspected abnormalities were noted (11%). The abnormalities involved the lung ( n = 4), the liver ( n = 3), the gallbladder ( n = 4), the esophagus ( n = 2), lymph nodes ( n = 3), and the breast. All abnormalities were evaluated with additional imaging studies and/or appropriate consultations. Four of these abnormalities represented additional cancer foci (3%) and altered the treatment plan. Conclusions: Three-dimensional treatment-planning CT scans for breast cancer should be carefully reviewed. In our institution, 11% of these planning studies contained abnormalities, and 3% demonstrated additional unanticipated sites of involvement by breast cancer.