Koos Boeve

58 Chapter 3 Table 1. Continued Demographic Characteristics Overall, n (%) Histopathological status of SLNB p-value pN0, n (%) pN+ (%) Tumour border configuration Pushing 54 (59) 45 (68) 9 (36) 0.008 Infiltrative 37 (41) 21 (32) 16 (64) Differentiation grade Well 29 (32) 21 (32) 8 (32) 1.000 Moderate 62 (68) 45 (68) 17 (68) Follow up data Time in months median (IQR) 32 (21-47) 37 (22-49) 25 (19-33) 0.014 total range 2-104 Recurrence Local / 2nd primary 9 (10) 5 (8) 4 (16) ** Isolated regional rec. 5 (5) 2 (3) 3 (12) Dead Dead of disease 3 (3) 0 (0) 3 (12) ** Dead not of disease 7 (8) 6 (9) 1 (4) Abbreviations: SLNB: sentinel lymph node biopsy. pN0: SLNs negative for metastases. pN+: SLNs positive for metastases. NA: not applicable. IQR: interquartile range. FOM: floor of mouth. Rec: recurrence *: Tongue vs floor of mouth, other subgroups too small to analyse. **: Group too small to analyse Surgical procedure SLNswereharvestedwith a small incision in theneck after gammaprobe assisted localization. The neck side of the SLNB was indicated by the results of the lymphoscintigraphy. In 28 (31%) patients, non-SLNs were harvested due to location of the SLN in a conglomerate of lymph nodes or the impossibility to remove the SLNs without harvesting these non-SLNs. SLNs were separated from the non-SLNs ex vivo using the gamma-probe in the operation theatre. Finally, the neck background radioactivity was checked with the gamma-probe to make sure that no SLN was left behind. Blue-dye was used intra-operatively in fourteen patients but not on regular base in both hospitals. Histopathological procedure SLNswere histopathologically examinatedby step serial sectioning of the entire SLNswith an interval of 500 µm, conventional staining with hematoxyline-eosine (H&E) and an additional pan-cytokeratin antibody (AE 1/3) immunohistochemistry staining. The non-SLNs were