THE USE OF TL-201 IN THE PREOPERATIVE DETECTION OF BREAST-CANCER - ANADJUNCT TO MAMMOGRAPHY AND ULTRASONOGRAPHY

Thallium-201 breast scans were performed preoperatively in 72 female p atients with breast abnormalities detected by mammography and/or ultra sonography (7.5-13 MHz), in order to differentiate benign from maligna nt breast disease. informed consent was obtained from each patient. Sc intigraphy consisted of anterior and oblique planar images of the affe cted breast and axilla at 10 min and 3 h following the injection of (T I)-T-201 chloride (110 MBq). All (TI)-T-201 scans were interpreted wit hout prior knowledge of surgery data. Pathological features of breast malignancies, such as tumour size, axillary lymph node metastases, tum our grading, lymphatic vascular channel invasion and receptor status, were analysed for their association with (TI)-T-201 uptake by tumour c ells. A total of 76 breast lesions were assessed in the study. On fina l histological diagnosis, there were 56 malignant tumours, 14 benign n odules (9 fibroadenomas, two cases of adenosis, two cases of focal fib rosis and one case of epitheliosis) and six atypical lesions (atypical ductal or lobular hyperplasia). Thallium scintigraphy was shown to ha ve high accuracy (92%) in detecting breast cancer, better than mammogr aphy (74%) and ultrasonography (84%). Almost all (51/56) breast cancer s showed greater (TI)-T-201 activity than surrounding normal breast ti ssue while there was no significant increase in (TI)-T-201 activity ab ove background in all but one (19/20) case of non-malignant disease. ( TI)-T-201 activity within breast tumours, calculated as tumour/backgro und (T/B) ratio, ranged between 1.2 and 2.5 with a mean value of 1.45. In our experience the concentration of thallium in the breast cancer seems to be primarily dependent on vascularity and tumour size rather than tumour grading, lymphatic/vascular invasion or receptor status. ( TI)-T-201 scan sensitivity was 97% for malignant lesions larger than 1 .5 cm (n=35) and 80% for lesions of 1.5 cm or less (n=21); however, fi ve of the eight breast cancers smaller than 1.0 cm were also detectabl e by (TI)-T-201 scintigraphy, compared with five out of seven by mammo graphy. Thallium scintigraphy would not be useful in evaluating the ax illa for lymph node metastases (sensitivity 27%, specificity 77%).