Tumor depth of invasion versus tumor thickness in guiding regional nodal treatment in early oral tongue squamous cell carcinoma.

OBJECTIVES: Tumor thickness (TT) and tumor depth of invasion (DOI) correlate with the risk of regional lymph node metastases in early oral tongue squamous cell carcinoma (OTSCC). We aimed to determine optimal cutoff points to guide elective nodal treatment in early OTSCC. STUDY DESIGN: This retrospective study included 145 patients treated between 1995 and 2012 for histologically proven OTSCC (<4 cm). The minimum P value method was used to calculate the cut-point values of TT and DOI that predicted for nodal disease. The utility of the DOI cut-point value and the 5-mm DOI currently used for staging were then compared. RESULTS: Logistic regression analysis demonstrated that DOI (P = .00036) and TT (P = .0001) were highly correlated with nodal disease and each other. The cut-points that best predicted for nodal disease were 4.5 mm for DOI and 8 mm for TT. There was no difference in utility between DOIs of 4.5 mm and 5 mm. CONCLUSIONS: TT and DOI were highly correlated with nodal risk but had different cut-points for prediction. Our findings highlight the need to recognize these parameters as discrete entities and to report them appropriately. This study's findings support the use of the 5-mm DOI, currently used for staging, as also the threshold value to guide elective nodal treatment.

Humidity-Dependent Surface Structure and Hydroxide Conductance of a Model Quaternary Ammonium Anion Exchange Membrane.

Anion exchange membrane (AEM) fuel cells (AEMFCs) are a promising cost-effective alternative energy conversion technology because of the potential implementation of earth-abundant catalysts, obviating the need for precious metals. AEMs, however, have low conductivity and suffer from poor stability. The conductivity of the AEM is inherently tied to the complex phase-separated morphology, as its dependence on the hydration level is not well understood. In this report, we employ phase-contrast tapping mode and conductive-probe atomic force microscopy (cp-AFM) to study the nanoscale surface morphology and hydroxide conductance of a commercially available quaternary ammonium (QA) AEM by FuMA-Tech GmbH (Fumapem FAA-3). The chemical structure of FAA-3 consists of a poly(phenylene oxide) backbone with QA functionality. The morphology of FAA-3 was observed in the bromide (FAA-3-Br-) and hydroxide form (FAA-3-OH-) in dehydrated and hydrated conditions. Under dehydrated conditions, both membranes showed no phase contrast, indicating the absence of phase-separated hydrophilic domains at the surface. At hydrated conditions, FAA-3-Br- shows randomly dispersed isolated clusters, while FAA-3-OH- shows elongated fibrillar structures extending microns in length. cp-AFM of hydrated FAA-3-OH- showed that these elongated regions were insulating. These results provide morphological evidence for the conduction of hydroxide at the surface and its dependence on the hydration level.