Koos Boeve

134 Chapter 7 were selected for watchful waiting without using cortactin, six (18%) would have had an incorrect neck staging strategy (Figure 2). If cortactin was used as predictive marker for N-status, 26 (79%) patients would have been selected for a watchful waiting strategy based on a low cortactin expression and only two (8%) patients would have a positive true N-status whereas 24/26 (92%) indeed would be true negative (Figure 2). None of the clinico-pathological characteristics or biomarkers were associated with true N-status in the remaining 54 patients with a pT1 or pT2 staged tumor and a tumor infiltration depth ≥4 mm. Table 3. Molecular biomarkers in pT1cN0 staged OSCC with a tumor infiltration depth <4 mm True N negative True N positive p-value n (%) n (%) Cortactin low expression 24 (89) 2 (33) 0.011 high expression 3 (11) 4 (67) Cyclin D1 low expression 13 (48) 2 (33) 0.665 high expression 14 (52) 4 (67) FADD low expression 22 (82) 2 (43) 0.034 high expression 5 (18) 4 (57) RAB25 low expression 15 (56) 4 (67) 1.000 high expression 12 (44) 2 (33) S100A9 nuclear low expression 18 (67) 4 (67) 1.000 high expression 9 (33) 2 (33) S100A9 cytoplasmic low expression 14 (52) 4 (67) 0.665 high expression 13 (48) 2 (33) True N-status is determined by the combination of postoperative pathological lymph node status (pN) combined with regional recurrence (false negatives). Patients with a negative SLNB (pN0) and diagnosed with a regional recurrence were counted as true N positives. Cortactin and FADD expression were significantly associated with true N-status in pT1cN0 staged OSCC and a tumor infiltration depth <4 mmwith the highest sensitivity of 67% (4/(4+2)) and negative predictive value of 92% (24/(24+2)) for cortactin.