Prediction of Sentinel Lymph Node Biopsy Status in Breast Cancers with PET/CT Negative Axilla

Background and Aim  Prior knowledge of axillary node status can spare a lot of patients with early breast cancer morbidity due to an unnecessary axillary dissection. Our study compared various metabolic and pathological features that can predict the sentinel lymph node biopsy (SLNB) status in patients with positron emission tomography/computed tomography (PET/CT) negative axilla. Patients and Methods  All consecutive patients with early breast cancers (< 5 cm) with PET/CT negative axilla who underwent breast surgery and SLNB from November 2016 to February 2020 were included. Various primary tumor (PT) pathological variables and metabolic variables on PET/CT such as maximum standardized uptake value (PT-SUV _max ), metabolic tumor volume (PT-MTV), and total lesion glycolysis (PT-TLG) were compared using univariate and multivariate analyses for prediction of SLNB status. Results  Overall 70 patients, all female, with mean age 55.6 years (range: 33-77) and mean tumor size 2.2 cm (range: 0.7-4.5), were included. SLNB was positive in 20% of patients ( n  = 14) with nonsentinel nodes positive in 4% ( n  = 3) patients. Comparing SLNB positive and negative groups, univariate analysis showed significant association of SLNB with low tumor grade, positive lymphovascular invasion (LVI), positive estrogen receptor (ER) status with lower mean K _i -67 index (34.41 vs. 52.02%; p  = 0.02), PT-SUV _max (5.40 vs. 8.68; p  = 0.036), PT-MTV (4.71 cc vs. 7.46 cc; p  = 0.05), and PT-TLG (15.12 g/mL.cc vs. 37.10 g/mL.cc; p  = 0.006). On multivariate analysis, only LVI status was a significant independent predictor of SLNB status (odds ratio = 6.23; 95% confidence interval: 1.15-33.6; p  = 0.033). Conclusion  SLNB is positive in approximately 20% of early breast cancers with PET/CT negative axilla and SLNB status appears to be independent of PT size. SLNB+ PTs were more likely to be LVI+ and ER + ve, with lower grade/K _i -67/metabolic activity (SUV _max /MTV/TLG) compared with SLNB-ve tumors. Logistic regression analysis revealed LVI status as the only significant independent predictor of sentinel lymph node status.