Oral pathology and oral medicine in Latin American countries: current stage.

BACKGROUND: Oral Pathology (OP) and Oral Medicine (OM) are specialties in dentistry whose main objective is the diagnosis and treatment of oral and maxillofacial diseases, and aspects related to the academic training of professionals and fields of practice are distinct and heterogeneous around the world. This study aimed to evaluate professional training and areas of activity in OP and OM in Latin American countries. MATERIAL AND METHODS: A questionnaire was sent to 11 countries, with a professional in each country responsible for answering it. The questionnaire had 21 questions related to the process of professional training, areas of practice, the existence of scientific events in each country, and also collected demographic and population information. RESULTS: OP and OM are practiced in all the countries studied, but the specialty is not recognized in all of them. Brazil was the first to recognize both as a specialty. Postgraduate programs designed to train specialists are available in various countries. Two countries offer residency programs, 6 countries provide specialization courses, 6 offer master's programs, and 3 have doctoral programs. Brazil boasts the highest number of undergraduate courses (n=412), while Uruguay has the lowest (n=2). Professional societies representing the specialty exist in ten countries. Brazil has the highest number of OP and OM specialists (n=422 and 1,072), while Paraguay has the smallest number (n=1 and 3). CONCLUSIONS: Although both specialties are widely practiced around the globe, professional training, the number of dentists trained and the fields of professional practice are very different between the countries studied.

Perineural invasion predicts poor survival and cervical lymph node metastasis in oral squamous cell carcinoma.

BACKGROUND: Oral squamous cell carcinoma (OSCC) usually invades peripheral nerves through a process known as perineural invasion (PNI), recognized as an adverse factor considered for the administration of postoperative adjuvant therapy. The aim of this study was to assess the impact of PNI on survival and cervical lymph node metastasis in a cohort of OSCC patients. MATERIAL AND METHODS: Presence, location and extension of PNI were assessed in a cohort of 57 paraffin-embedded OSCC resections. Clinico-pathological variables were obtained from each case. Five-year overall survival (OS) and 5-year disease-specific survival (DSS) curves were constructed according to the Kaplan-Meier method and compared with log-rank test. The Cox proportional hazard model was used to assess the role of PNI as an independent risk factor related to poor survival, and a binary logistic regression was performed to estimate the predictive value of PNI for regional lymph node metastasis. RESULTS: PNI was observed in 49.1% of the cases, affecting only small nerves. Peritumoral PNI was the most common location, and multifocal PNI the most frequent extent. Most PNI positive cases had cervical metastasis (p=0.001), and PNI was more frequent in stages III-IV than in I-II (p=0.02). The five-year OS and the 5-year DSS decreased in PNI positive and peritumoral PNI cases. PNI was an independent risk factor for poor 5-year OS and poor 5-year DSS. The odds for cervical lymph node metastasis were of 6.076 (p=0.006) and 10.257 (p=0.007) for PNI and Tumor budding (TB) positive cases, respectively. CONCLUSIONS: PNI is a frequent finding in OSCC and an independent risk factor for poor OS and DSS. PNI and TB are both risk factors associated to an increased likelihood for the development of lymph node metastasis. Therefore, we suggest further investigations to test the combined PNI-TB scoring system in risk stratification models for OSCC.

Histopathological parameters reported in microinvasive oral squamous cell carcinoma: a systematic review.

BACKGROUND: Microinvasive oral squamous cell carcinoma (OSCCmi) is an incipient stage of oral cancer. Through this systematic review, we aim to assess patterns of histopathological outcomes reported in OSCCmi cases. MATERIAL AND METHODS: An online search in major databases was performed without period restriction, and 2,024 publications in English, Spanish and Portuguese were obtained. After screening and eligibility, 4 studies were selected. The risk of bias was assessed using Joanna Briggs Institute Critical Appraisal Checklist. A descriptive synthesis was conducted. RESULTS: All 4 publications included were retrospective, reporting a total of 116 OSCCmi patients, with a male predominance (1.6:1) and a mean age of 55.9 years. The main parameters considered for microinvasion were tumor thickness (TT) (range 4-10mm) and depth of invasion (DOI) (range 0,02-5mm). Definition, cut-off values, and assessment of microscopic features were not standardized. Other relevant measures such as perineural or lymphovascular invasion and pattern of invasive front were barely described, and cytological/architectural characteristics were not discussed. CONCLUSIONS: TT and DOI are currently the primary histopathological criteria used to define OSCCmi. Nonetheless, the outcomes of this systematic review showed the absence of standardized quantitative parameters to render the diagnosis of microinvasive OSCC. Therefore, additional studies aiming to standardize histopathological features to diagnose OSCCmi are paramount.

MicroRNAs and their role in the malignant transformation of oral leukoplakia: a scoping review.

BACKGROUND: MiRNAs are small non-coding RNAs that regulate gene expression at the post-transcriptional level and have been associated with malignant transformation of oral epithelial precursor lesions such as oral leukoplakia. The aim was to perform a scoping review of the contemporary literature about the different roles of miRNAs during the malignant transformation of oral leukoplakia. MATERIAL AND METHODS: We conducted a systematic search with the following MeSH terms: 'oral leukoplakia', 'carcinoma in situ', 'microRNAs', 'mouth neoplasms' and 'epithelial-mesenchymal transition' in PubMed/MEDLINE, EMBASE and SpringerLink. RESULTS: Fifteen articles were included for analysis, among which in vivo and in vitro articles were included. A total of 21 different miRNAs were found to be involved in the malignant transformation process of oral leukoplakia. Regarding their possible effects, 6 miRNAs were classified as oncogenic, 5 as tumour suppressors and 10 were related to epithelial-mesenchymal transition, invasion and migration. CONCLUSIONS: Based on the current review, we concluded that miRNAs-21, 345, 181-b and 31* seem to be potential markers of malignant transformation of oral leukoplakia. However, further clinical prospective studies are needed in order to validate their utility as prognostic biomarkers.

The impact of head and neck radiotherapy on the dentine-enamel junction: a systematic review.

BACKGROUND: Radiotherapy is widely used in contemporary head and neck cancer treatment protocols. The ability of head and neck radiotherapy (HNRT) to cause direct radiogenic destruction to the teeth is one of the most controversial topics in the field of oral oncology. Therefore, this systematic review aimed to investigate ionising radiation as an independent factor for physical and chemical changes on the dentine-enamel junction (DEJ), a pivotal dental topography for the onset and progression of radiation-related caries (RRC) and enamel delamination. MATERIAL AND METHODS: Systematic searches were conducted on three databases: Scopus, MEDLINE (Via PubMed) and Embase (Elsevier). Laboratory studies evaluating the effects of simulated or in vivo HNRT on the DEJ were included. The GRADE tool adapted for in vitro studies was used to assess the methodological quality. RESULTS: Of the 154 initially selected studies, eight met the inclusion criteria, from which five studies were graded as high quality of evidence, two studies were graded as moderate quality and one as low quality. Two studies did not demonstrate DEJ alterations following HNRT while the other six articles described several organic and inorganic changes in the DEJ of irradiated teeth samples. These radiogenic events were mostly detected through micro and nanoindentation, Raman micro-spectroscopy, confocal microscopy, Western blotting and optical coherence tomography. CONCLUSIONS: HNRT may have a negative impact on the physical and chemical aspects of the DEJ, predisposing cancer patients to RRC and enamel delamination.

Prognostic value of immunoexpression of CCR4, CCR5, CCR7 and CXCR4 in squamous cell carcinoma of tongue and floor of the mouth.

BACKGROUND: Diverse studies have evidenced that chemokines can play a critical role in pathogenesis of oral squamous cell carcinoma (SCC). The main chemokines involved in oral carcinogenesis, tumor invasion and metastasis are CCR4, CCR5, CCR7 and CXCR4, and our aim was to evaluate the prognostic value of the immunoexpression of these chemokines in SCC of tongue and floor of the mouth. MATERIAL AND METHODS: A retrospective descriptive study of the immunohistochemical expression of CCR4, CCR5, CCR7 and CXCR4 in paraffin-embedded samples of 124 patients with SCC of the tongue and floor of the mouth was performed, considering 98 cases from Brazil and 26 cases from Chile. Associations between variables were analyzed using chi-square test. Survival curves were performed using the Kaplan-Meier method and compared with long-rank test. For multivariate survival analysis, the Cox hazard model was established. The level of significance established was p≤0.05. RESULTS: The statistical analysis showed that samples with well or moderate WHO model differentiation (p=0.001) and a high expression of CCR5 (p=0.05) were significantly associated with a higher disease specific survival, which were also observed in Cox's multivariate analysis (p=0.01). A higher expression of CCR7 (p=0.01) interfered significantly in disease-free survival in univariate analysis and in Cox's multivariate analysis (p=0.05). CONCLUSIONS: These results support additional evidence, showing that chemokine receptors CCR5 and CCR7 are helpful as biomarkers of poor prognosis in patients with SCC of the tongue and floor of the mouth.

Clinicopathological significance of miR-26, miR-107, miR-125b, and miR-203 in head and neck carcinomas.

OBJECTIVES: MicroRNAs play a role in the development and progression of head and neck squamous cell carcinomas (HNSCC). Our aim was to study the expression of miR-26, miR-107, miR-125b, and miR-203 in primary HNSCC with and without lymph node metastasis and their clinicopathological significance. MATERIALS AND METHODS: The expression of microRNAs in primary HNSCC with lymph node metastasis (n = 16) and their matched lymph node, as well as primary tumors without metastasis (n = 16), were determined by quantitative RT-PCR and analyzed with clinicopathological features and survival. RESULTS: The expression levels of miR-26 (p < .05) and miR-125b (p < .01) were higher in metastatic primary HNSCC, while levels of miR-203 (p < .01) were lower. The expression of the microRNAs was associated with clinicopathological features, including miR-26 high expression and N stage (p = .04), poor differentiation (p = .005) and recurrence (p = .007), miR-125b high expression and N stage (p = .0005) and death (p = .02), and low levels of miR-203 and N stage (p = .04). The high expression of miR-26 was associated with shortened disease-free survival, and high miR-125b expression was an independent risk factor for poor disease-specific survival. CONCLUSIONS: These findings suggest that miR-26 and miR-125b may be associated with the progression and metastasis of HNSCC and that miR-203 is associated with a more favorable prognosis.