PROSPECTIVE EVALUATION OF FLUORINE-18-FDG PET IN PRESURGICAL STAGING OF THE AXILLA IN BREAST-CANCER

Methods: The presurgical, noninvasive staging of axillary nodes for me tastases was prospectively investigated in 68 patients who were diagno sed with primary breast cancer using PET with F-18-fluorodeoxyglucose (FDG). Four patients had bilateral nodules; therefore, the total numbe r of evaluable cases was 72. Visual analyses of attenuation-corrected PET images and standardized uptake values (SUVs) of FDG uptake in carc inomas were compared with histopathological surgical findings. The SUV distribution differences between carcinomas with and without axillary metastases were evaluated by means of statistical and receiver operat ing characteristics analyses. Results: PET correctly classified 64 of the 72 cases; four false-positive and four false-negative PET results were found. The overall sensitivity, specificity and accuracy of PET f or axillary metastases were 85%, 91% and 89%, respectively. With respe ct to the clinical axillary stage of the patients (TNM, or tumor-node- metastasis, classification), we obtained the following results: N-o pa tients, sensitivity = 70%, specificity = 92%, accuracy = 86%; N-1a pat ients, sensitivity = 85.5%, specificity = 100%, accuracy = 95%; and N1 b-2 patients, sensitivity = 100%, specificity = 67%, accuracy = 87%. T he median SUV in carcinomas with axillary metastases (4.6) was signifi cantly higher than that in carcinomas without metastases (2.9), but th ere was a great SUV overlap between the two groups (interquartile rang es = 2.7-7.2 and 1.4-4.5, respectively), Analysis of the receiver oper ating characteristics curve showed that a high sensitivity of SUV in p redicting axillary metastases was associated with a very low specifici ty and vice versa. With the best SUV cutoff value of 2.9, the sensitiv ity and specificity were 74% and 56%, respectively, Conclusion: PET sh owed good overall diagnostic accuracy in the detection of axillary met astases (86%). The very high accuracy (95%) in N-1a patients is of par ticular importance. False-negative PET findings, however, can be encou ntered, SUVs of breast carcinoma cannot predict the spread of the dise ase to the axilla, even if higher values are often associated with axi llary metastases. Any decision on the use of PET in the presurgical st aging of breast cancer should be incorporated into a more general deba te on axillary management, In selected patients with a very low probab ility of axillary metastases (T-1a), in whom axillary surgery can alre ady be avoided according to data from follow-up studies, F-18-FDG PET could be proposed as a noninvasive imaging modality to improve the dia gnosis of axillary relapses.