Is FDG maximum standardized uptake value (SUV max) of primary breast cancer can predict axillary lymph node metastasis?

Background: Functional imaging with 18F-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography(PET/CT) is increasingly used for diagnosis and staging and restaging of breast cancer (BC) patients.

Purpose: To evaluate the validity of 18F-FDG PET/CT metabolic activity parameter maximum standardized uptake value of the primary tumor (SUVmax-T) to predict locoregional axillary lymph node metastasis (ALNM) in initial staging of BC patients. Materials and Methods: We prospectively studied 40 female patients with different stages pathologically proven breast cancer. All patients were submitted to 18F-FDG PET/CT imaging for their initial tumor staging. The SUVmax-T and SUVmax ALN on 18F-FDGPET/CT were assessed. The patients were categorized into two groups; group I, with positive ALN uptake, and groupII with negative ALN uptake, according to the presence of locoregional 18F-FDG ALN uptake on visual &quantitative analysis of 18F-FDG PET/CT. The correlations and differences between two groups were statistically evaluated. The optimal cut-off value of SUVmax-T was determined.

Results: Forty female patients with newly diagnosed BC were included in our study, age range from 31-78 (mean 50.5 +/- SD11.7). All the 1ry tumors were detected with mean SUVmax 10.8(+/-SD 7.9). In the Twenty-Three patients who underwent nodal staging (axillary dissection in 7/23 patients and SLNBs in 16/23 patients.), 13/23 and 10/23 patients were positive and negative for metastases respectively.PET/CT was positive in 27 patients with ALNs; out of them 13 proved true positive, 4 were false positive by histopathology and in the remaining 10 cases no pathology report was available. PET/CT negative axillary cases were 13 out of them 6 were true negative by histopathology and in the remaining 7 cases no pathology report were available. The mean tumor size in group I was significantly greater than that in group II (3.1+/- SD 1 , P value 0.011). The mean SUVmax-T value in group A was significantly higher than that in group B ((Mean 12.7+/- SD 8.6 ,Pvalue 0.016). Tumor stage &nuclear grade in group A was higher than that in group B (P value 0.372, 0.252 respectively). SUVmax -T were significantly moderately positively correlated with the size of the 1ry tumor (rho= 0.328, P value=0.019 . SUVmax -T was predictive of axillary nodal involvement AUC= 0.735(95% CI: 0.577-0.893). The optimal cut-off of SUVmax-T for detecting ALNM was>1.9 gives sensitivity 100% and specificity 92%. with overall sensitivity and specificity of PET/CT for axillary staging was 100 % and 60 %, respectively (P value= 0.006).

Conclusions: BC patients with higher FDG SUVmax of primary tumor are at greater risk of concurrent ALNM. Keywords: Breast cancer. FDG PET/CT . SUVmax. Initial staging. Axillary lymph nodal metastasis, prognosis.