Salivary gland polymorphous adenocarcinoma: Clinicopathological features and gene alterations in 36 Japanese patients.

BACKGROUND: Polymorphous adenocarcinoma is a common intraoral minor salivary gland carcinoma in Western countries but is extremely rare in Japan. The current study aimed to characterize the clinicopathological features and status of molecular alterations of polymorphous adenocarcinoma-associated genes, such as PRKD1/2/3, ARID1A, and DDX3X, in a large cohort of Japanese patients with polymorphous adenocarcinoma. METHODS: We examined the cases of 36 Japanese patients with salivary gland polymorphous adenocarcinoma and 26 cases involving histopathological mimics. To detect gene splits, fluorescence in situ hybridization was carried out for polymorphous adenocarcinoma-associated genes. Additionally, we applied a SNaPshot multiplex assay to identify PRKD1 hotspot mutations. RESULTS: This study revealed the indolent clinical course of polymorphous adenocarcinoma with a high 10-year overall survival rate (92.9%), accompanied by occasional local recurrences and cervical lymph node metastasis (23.3%). Twenty cases (55.6%) of polymorphous adenocarcinoma (but none of the mimics) exhibited alterations in at least one polymorphous adenocarcinoma-associated gene. Rearrangement of polymorphous adenocarcinoma-associated genes and PRKD1 E710D were identified in 17 (47.2%) and 4 (11.1%) cases, respectively; one case showed coexisting PRKD3 split and PRKD1 E710D. In the multivariate analysis, high clinical stage (p = 0.0005), the presence of prominent nucleoli (p = 0.0003), and ARID1A split positivity (p = 0.004) were independent risk factors for disease-free survival. CONCLUSION: Japanese patients with polymorphous adenocarcinoma showed clinicopathological features similar to those reported in Western countries. This study disclosed that polymorphous adenocarcinoma-associated genetic alterations were common and specific findings in polymorphous adenocarcinomas. The diagnostic role and possible prognostic significance of polymorphous adenocarcinoma-associated genetic alterations in polymorphous adenocarcinomas were suggested.

The prognostic significance of intratumoral heterogeneity of 18F-FDG uptake in patients with oral cavity squamous cell carcinoma.

PURPOSE: This study aimed to evaluate the prognostic significance of two major indices of intratumoral heterogeneity of 18F-fluorodeoxyglucose uptake by positron emission tomography (PET)/computed tomography (CT), namely heterogeneity index (HI) and heterogeneity factor (HF), in patients with oral squamous cell carcinoma. METHODS: We performed a retrospective analysis of 62 patients who underwent resective surgery. HI, HF, maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were obtained from pretreatment PET. HI was obtained by dividing SUVmax by SUVmean for the primary lesion; HF was obtained by taking the derivative (dV/dT) of the volume-threshold function from 30 to 70%. Univariate and multivariate analyses for the overall survival (OS) and disease-free survival (DFS) were performed using PET and clinicopathological parameters. RESULTS: Univariate and multivariate analyses of OS revealed that higher HI levels (threshold for the SUVmean is 30% of the SUVmax) were associated with poorer OS [hazard ratio (HR) = 11.57; 95% confidence interval (CI) = 1.45-92.28; P = 0.021]. Moreover, univariate and multivariate analyses of DFS revealed that higher TLG levels (threshold for the MTV and SUVmean is 4.0 of the SUV) were associated with poorer DFS (HR = 14.48; 95% CI = 1.27-164.78; P = 0.031). CONCLUSIONS: HI and TLG may be statistically significant prognostic factors for OS and DFS, respectively.