Rac1 activation in oral squamous cell carcinoma as a predictive factor associated with lymph node metastasis.

OBJECTIVES: Secondary lymph node metastasis (SLNM) indicates a poor prognosis, and limiting it can improve the survival rate in early-stage tongue squamous cell carcinoma (TSCC). Many factors have been identified as predictors of SLNM; however, there is no unified view. Ras-related C3 botulinum toxin substrate 1 (Rac1) was found to be a promoter of the epithelial-mesenchymal transition (EMT) and is also attracting attention as a new therapeutic target. This study aims to investigate the role of Rac1 in metastasis and its relationship with pathological findings in early-stage TSCC. MATERIALS AND METHODS: Rac1 expression levels of 69 cases of stage I/II TSCC specimens and their association with clinicopathological characteristics were evaluated by immunohistochemical staining. The role of Rac1 in oral squamous cell carcinoma (OSCC) was examined after Rac1 in OSCC cell lines was silenced in vitro. RESULTS: High Rac1 expression was significantly associated with the depth of invasion (DOI), tumor budding (TB), vascular invasion, and SLNM (p < 0.05). Univariate analyses revealed that Rac1 expression, DOI, and TB were factors significantly associated with SLNM (p < 0.05). Moreover, our multivariate analysis suggested that Rac1 expression was the only independent determinant of SLNM. An in vitro study revealed that Rac1 downregulation tended to decrease cell migration and proliferation. CONCLUSION: Rac1 was suggested to be an important factor in the metastasis of OSCC, and it could be useful as a predictor of SLNM.

Assessment of squamous cell carcinoma of the floor of the mouth with magnetic resonance imaging.

PURPOSE: We aimed to use magnetic resonance imaging (MRI) to determine the relationship between the pathological depth of invasion (DOI), undetectability, and tumor thickness of squamous cell carcinoma of the floor of the mouth. MATERIALS AND METHODS: We retrospectively evaluated the relationship between pathological DOI and MRI detectability, as well as the relationship between pathological DOI and tumor thickness on coronal fat-suppressed contrast-enhanced T1-weighted imaging or coronal T2-weighted imaging. RESULTS: We analyzed 30 patients with squamous cell carcinoma of the floor of the mouth; MRI revealed that the pathological DOI of the 11 undetectable lesions (median 2 mm) was smaller than that of the 19 detectable lesions (median 14 mm) (p < 0.001), and the cut-off value was 3 mm (sensitivity, 0.84; specificity, 0.91; area under the curve, 0.89). Tumor thickness on coronal fat-suppressed contrast-enhanced T1-weighted imaging was assessed in all 19 detectable lesions; however, tumor thickness on coronal T2-weighted imaging could not be assessed in eight cases. Tumor thickness on coronal fat-suppressed contrast-enhanced T1-weighted imaging was found to be significantly associated with the pathological DOI. CONCLUSIONS: Undetectability on MRI indicates superficial lesions with a pathological DOI value that is less than 3 mm. In detectable lesions, tumor thickness on coronal fat-suppressed contrast-enhanced T1-weighted imaging is associated with pathological DOI.

Correlation between the magnetic resonance imaging features of squamous cell carcinoma of the buccal mucosa and pathologic depth of invasion.

OBJECTIVE: The objective of this study was to determine correlations between magnetic resonance imaging (MRI) features including radiologic depth of invasion (r-DOI) and pathologic DOI (p-DOI) of squamous cell carcinoma of the buccal mucosa. STUDY DESIGN: In total, 31 lesions were retrospectively evaluated. MRI findings included detectability, buccinator muscle invasion (positive: BMI+, negative: BMI-), buccal fat pad invasion (positive: BFPI+, negative: BFPI-), and r-DOI measured on T2-weighted images (T2-DOI) and contrast-enhanced T1-weighted images (CET1-DOI). These findings were compared to the p-DOI of the tumors. RESULTS: The p-DOI values of undetectable lesions were smaller than those of detectable lesions (P < .001), and the cutoff value was 1 mm. BMI+ and BFPI+ lesions had significantly larger p-DOI values than the corresponding BMI- and BFPI- lesions (P < .001), with cutoff values of 5 and 6 mm, respectively. The correlation coefficient between CET1-DOI and p-DOI was 0.68 (P < .001). CET1-DOI values were larger than p-DOI (P < .001) and the average difference between them was 3.4 mm. T2-DOI was inconclusive in 50% of cases. Interobserver agreements of MRI evaluation were good to very good. CONCLUSION: MRI-derived parameters were useful in estimating p-DOI and may be helpful in predicting the depth of invasion of tumors and the risk of lymph node metastasis.

Effect of postoperative radiotherapy for free flap volume changing after tongue reconstruction.

OBJECTIVE: The purpose of this study was to evaluate the effect of postoperative radiotherapy (RT) on temporal volume changes with a cutaneous free flap (CF) and a myocutaneous free flap (MCF). METHODS: The subjects were 24 men and 11 women (mean age, 50.5 ± 15.5 years) with tongue or floor of mouth cancer. Twenty-seven cases of CF and eight cases of MCF were selected. The flap volume change of the reconstructed tongue was calculated using computed tomography (CT) images taken immediately and at one year postoperatively using the DICOM image processing software OsiriX®. RESULTS: The reduction rate in flap volume at one year postoperatively was 82.0 ± 15% in CF without RT, 70.3 ± 26.1% in CF with RT, 88.5 ± 14.7% in MCF without RT, and 99.5 ± 16% in MCF with RT. The MCF volume was significantly higher compared to the CF volume. Although postoperative RT reduced the CF volume by 30%, there was only a slight reduction in the MCF volume. CONCLUSIONS: We evaluated the effect of postoperative RT on volume reduction in 35 cases of the reconstructed tongue with CF and MCF using a computer-assisted volume rendering technique. In this study, the effect of RT on volume reduction was different between the CF and MCF.