Koos Boeve

133 Molecular biomarkers in SLNB staged early oral cancer Numberwofwpatients 0 10 20 30 40 Nowusewofwcortactinwexpression 9onlywSLNB-procedure5 Lowwcortactinwexpression 9watchfulwwaiting5 Highwcortactinwexpression 9SLNB-procedure5 Neckwstagingwwithoutwcortactin Neckwstagingwwusingwcortactin 188wpositive 828wnegative 88wpositive 928wnegative 578wpositive 438wnegative pw=w0.011 Figure 2. Differences between neck staging using only the sentinel lymph node biopsy procedure or combined with cortactin expression levels. The differences in selection of neck staging procedures in 33 patients with a pT1cN0 OSCC and a tumor infiltration depth <4 mm with and without using cortactin expression. These 33 patients had neck staging using SLNB while 82% had no neck lymph node involvement (negative true N-status). If these patients were selected for a watchful waiting procedure using cortactin expression, 8% out of 26 patients with a low cortactin expression would have been false negatives (positive true N-status) and 43% out of 7 patients with a high cortactin expression and without lymph node involvement (negative true N-status) would have had neck staging using SLNB procedure. To investigate whether patients with a low risk of occult metastasis could be identified for a watchful waiting strategy of the neck instead of a SLNB, we analyzed the additional value of these same molecular biomarkers in a subgroup of 33 patients with a pT1cN0 OSCC and a tumor infiltration depth <4 mm. Of these 33 low risk patients, 18% had a positive true N-status whereas 44% positive true N-status cases were observed within the 54 patients with pT1 or pT2 tumors and a tumor infiltration depth ≥4 mm (p = 0.019). In the 33 low risk patients, cortactin (OR 16.0, 95% CI 2.0-127.9) and FADD (OR 8.8, 95% CI 1.2-62.2) expression were strongly associated with true N-status. Cortactin and FADD showed overexpression in the same four patients with a positive true N-status. Cortactin expression as predictive marker for true N-status in these 33 low risk patients resulted in a sensitivity of 67% and NPV of 92% (Table 3). If these 33 pT1cN0 patients with tumor infiltration depth <4 mm