Cholesterol Is a Regulator of CAV1 Localization and Cell Migration in Oral Squamous Cell Carcinoma.

Cholesterol plays an important role in cancer progression, as it is utilized in membrane biogenesis and cell signaling. Cholesterol-lowering drugs have exhibited tumor-suppressive effects in oral squamous cell carcinoma (OSCC), suggesting that cholesterol is also essential in OSCC pathogenesis. However, the direct effects of cholesterol on OSCC cells remain unclear. Here, we investigated the role of cholesterol in OSCC with respect to caveolin-1 (CAV1), a cholesterol-binding protein involved in intracellular cholesterol transport. Cholesterol levels in OSCC cell lines were depleted using methyl-ß-cyclodextrin and increased using the methyl-ß-cyclodextrin-cholesterol complex. Functional analysis was performed using timelapse imaging, and CAV1 expression in cholesterol-manipulated cells was investigated using immunofluorescence and immunoblotting assays. CAV1 immunohistochemistry was performed on surgical OSCC samples. We observed that cholesterol addition induced polarized cell morphology, along with CAV1 localization at the trailing edge, and promoted cell migration. Moreover, CAV1 was upregulated in the lipid rafts and formed aggregates in the plasma membrane in cholesterol-added cells. High membranous CAV1 expression in tissue specimens was associated with OSCC recurrence. Therefore, cholesterol promotes the migration of OSCC cells by regulating cell polarity and CAV1 localization to the lipid raft. Furthermore, membranous CAV1 expression is a potential prognostic marker for OSCC patients.

Clinicopathologic factors influencing the screening accuracy of oral cytology: A retrospective cohort study.

Cytology is a simple and non-invasive screening method for oral cancer. However, this method is not yet routinely used by clinicians because of its high false negative rate (FNR) and due to lack of sufficient studies examining the factors for high FNRs. The present retrospective study aimed to compare the screening performance of conventional cytology (CC) and liquid-based cytology (LBC) through histological validation, and to elucidate factors inducing false negative screening in oral cytology. Cytological specimens with histological examination and intraoral digital images of the lesion were retrospectively collected between January 2017 and December 2018 for CC and between October 2019 and September 2021 for LBC. Oral cytological screening was conducted based on the oral Bethesda system for oral cytology. Clinical subtypes were re-evaluated using intraoral digital images. The screening accuracy of oral cytology was calculated considering the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for detecting the malignant transformation of oral lesions. No statistically significant difference was noted in the inadequate rate between CC and LBC groups. For CC and LBC, the sensitivities were 60.9 and 59.2%, the specificities were 87.3 and 79.1%, the PPVs were 85.8 and 76.2%, and the NPVs were 63.9 and 63.2%, respectively. Thus, the screening accuracy was similar between methodologies. Among the clinicopathological factors investigated, histological diagnosis and cellularity contributed to false negative results. Homogeneous findings of oral epithelial dysplasia and the superficial growth of carcinoma in situ/squamous cell carcinoma resulted in false negative findings for CC and LBC. Furthermore, LBC samples with a lower cell number (<2,000 squamous cells) exhibited statistically significantly increased FNRs. The present study found that the cytological methods did not affect the inadequate rate and screening accuracy, whereas clinical subtype and cellularity decreased screening accuracy. Therefore, cytological screening and subsequent follow-up should be performed while considering clinical findings and the cellularity of cytology smears.

Novel cytological model for the identification of early oral cancer diagnostic markers: The carcinoma sequence model.

Most oral squamous cell carcinomas (OSCCs) arise from a premalignant lesion, oral epithelial dysplasia; however, useful markers for the early detection of OSCC are lacking. The present study aimed to establish a novel experimental model to observe changes in the sequential expression patterns of mRNAs and proteins in a rat model of tongue cancer using liquid-based cytology techniques. Cytology specimens were collected at 2, 5, 8, 11, 14, 17 and 21 weeks from rats treated with 4-nitroquinoline 1-oxide to induce tongue cancer. The expression of candidate biomarkers was examined by performing immunocytochemistry and reverse transcription-quantitative PCR. The percentage of positively stained nuclei was calculated as the labeling index (LI). All rats developed OSCC of the tongue at 21 weeks. The mRNA expression levels of bromodomain protein 4 (Brd4), c-Myc and Tp53 were upregulated during the progression from negative for intraepithelial lesion or malignancy to squamous cell carcinoma (SCC). Brd4- and c-Myc-LI increased in low-grade squamous intraepithelial lesion, high-grade squamous intraepithelial lesion and SCC specimens. p53-LI was significantly increased in SCC specimens. This novel experimental model allowed the observation of sequential morphological changes and the expression patterns of mRNAs and proteins during carcinogenesis. Combining immunocytochemistry with cytology-based diagnoses may potentially improve the diagnostic accuracy of OSCC.

Oriental freshwater mussels arose in East Gondwana and arrived to Asia on the Indian Plate and Burma Terrane.

Freshwater mussels cannot spread through oceanic barriers and represent a suitable model to test the continental drift patterns. Here, we reconstruct the diversification of Oriental freshwater mussels (Unionidae) and revise their taxonomy. We show that the Indian Subcontinent harbors a rather taxonomically poor fauna, containing 25 freshwater mussel species from one subfamily (Parreysiinae). This subfamily most likely originated in East Gondwana in the Jurassic and its representatives arrived to Asia on two Gondwanan fragments (Indian Plate and Burma Terrane). We propose that the Burma Terrane was connected with the Indian Plate through the Greater India up to the terminal Cretaceous. Later on, during the entire Paleogene epoch, these blocks have served as isolated evolutionary hotspots for freshwater mussels. The Burma Terrane collided with mainland Asia in the Late Eocene, leading to the origin of the Mekong's Indochinellini radiation. Our findings indicate that the Burma Terrane had played a major role as a Gondwanan "biotic ferry" alongside with the Indian Plate.

Crosstalk between oral squamous cell carcinoma cells and cancer-associated fibroblasts via the TGF-ß/SOX9 axis in cancer progression.

Cancer-associated fibroblasts (CAFs) have important roles in promoting cancer development and progression. We previously reported that high expression of sex-determining region Y (SRY)-box9 (SOX9) in oral squamous cell carcinoma (OSCC) cells was positively correlated with poor prognosis. This study developed three-dimensional (3D) in vitro models co-cultured with OSCC cells and CAFs to examine CAF-mediated cancer migration and invasion in vitro and in vivo. Moreover, we performed an immunohistochemical analysis of alpha-smooth muscle actin and SOX9 expression in surgical specimens from 65 OSCC patients. The results indicated that CAFs promote cancer migration and invasion in migration assays and 3D in vitro models. The invading OSCC cells exhibited significant SOX9 expression and changes in the expression of epithelial-mesenchymal transition (EMT) markers, suggesting that SOX9 promotes EMT. TGF-ß1 signalling inhibition reduced SOX9 expression and cancer invasion in vitro and in vivo, indicating that TGF-ß1-mediated invasion is dependent on SOX9. In surgical specimens, the presence of CAFs was correlated with SOX9 expression in the invasive cancer nests and had a significant impact on regional recurrence. These findings demonstrate that CAFs promote cancer migration and invasion via the TGF-ß/SOX9 axis.

Is the South African leech Barbronia gwalagwalensis Westergren amp; Siddall, 2004 (Hirudinida: Erpobdelliformes: Salifidae) a Paleotropical species?

The freshwater leech family Salifidae Johansson has a Paleotropical range, with a hotspot of species richness in the Oriental Region, and a few species endemic to Africa, Madagascar, and Reunion. Barbronia gwalagwalensis Westergren Siddall, 2004 was thought to be a characteristic example of the latter group being a lineage endemic to South Africa. However, we found that this species also occurs in Asia (Myanmar and Korea). Our time-calibrated phylogeny based on the mitochondrial cytochrome c oxidase subunit I (COI) gene reveals that the split between the African and Asian populations of this species occurred in the mid-Pleistocene, approximately 1.3 Ma ago (95% HPD 0.7-2.1 Ma). The statistical biogeographic modeling indicates that a B. gwalagwalensis population in South Africa most likely originated due a long-distance dispersal event with a subsequent vicariance (probability = 88.9%). A Late Quaternary range extension towards South Africa is known to occur in some other freshwater taxa (e.g. the freshwater mussel Unio caffer Krauss species group), which agrees with our hypothesis on the ancient origin of the South African B. gwalagwalensis population. Conversely, we can assume that the African population of this species was recently introduced from Asia. If so, the high levels of genetic divergence between African and Asian populations could be a part of a more general phylogeographic pattern historically originated within the Asian subcontinent due to the isolation by orographic or marine barriers. These two alternative hypotheses need further research efforts, i.e. sampling and sequencing of other Barbronia taxa, the ranges of which are situated between South Africa and Southeast Asia, as well as of topotypes of B. weberi (Blanchard, 1897) from Indonesia. Finally, our results highlight that the salifid genus Barbronia Johansson originated in the Oriental Region and that these leeches share both recently and historically high potential for long-distance dispersal events.

New freshwater mussel taxa discoveries clarify biogeographic division of Southeast Asia.

While a growing body of modern phylogenetic research reveals that the Western Indochina represents a separate biogeographic subregion having a largely endemic freshwater fauna, the boundaries of this subregion are still unclear. We use freshwater mussels (Unionidae) as a model to reconstruct spatial patterns of freshwater biogeographic divides throughout Asia. Here, we present an updated freshwater biogeographic division of mainland Southeast Asia and describe 12 species and 4 genera of freshwater mussels new to science. We show that the Isthmus of Kra represents a significant southern biogeographic barrier between freshwater mussel faunas of the Western Indochina and Sundaland subregions, while the Indian and Western Indochina subregions are separated by the Naga Hills, Chin Hills, and Rakhine Yoma mountain ranges. Our findings highlight that the freshwater bivalve fauna of Southeast Asia primarily originated within three evolutionary hotspots (Western Indochina, Sundaland, and East Asian) supplemented by ancient immigrants from the Indian Subcontinent.

Freshwater mussels house a diverse mussel-associated leech assemblage.

Freshwater mussels (Unionida) are one of the most imperiled animal groups worldwide, revealing the fastest rates of extinction. Habitat degradation, river pollution and climate change are the primary causes of global decline. However, biological threats for freshwater mussels are still poorly known. Here, we describe a diverse ecological group of leeches (Hirudinea: Glossiphoniidae) inhabiting the mantle cavity of freshwater mussels. So far, examples of mussel-associated leech species are recorded from East Asia, Southeast Asia, India and Nepal, Africa, and North America. This group comprises a dozen glossiphoniid species with a hidden life style inside the mantle cavity of their hosts largely overlooked by researchers. We show that the association with freshwater mussels evolved independently in three leech clades, i.e. Batracobdelloides, Hemiclepsis, and Placobdella, at least since the Miocene. Seven mussel-associated leech species and two additional free-living taxa are described here as new to science.

Eight new freshwater mussels (Unionidae) from tropical Asia.

Freshwater mussels are sensitive to habitat and water quality, revealing the fastest rates of human-mediated global extinction among aquatic animals. These animals are especially diverse in tropical Asia, the faunas of which are characterized by high levels of endemism. Here we describe four new species and four new subspecies of freshwater mussels from Myanmar. Leoparreysia whitteni sp. nov., the smallest representative of this genus, was discovered from the Ayeyarwady and Chindwin rivers. Radiatula myitthanensis sp. nov. and R. chindwinensis sp. nov. were recorded from the Chindwin Basin, and R. mouhoti haungthayawensis ssp. nov. has been discovered from the Haungthayaw River. Indochinella pugio has been revised with a description of three subspecies: I. pugio viridissima ssp. nov. from the Sittaung, Bilin and Bago rivers, I. pugio daweiensis ssp. nov. from the Dawei River, and I. pugio paradoxa ssp. nov. from the Haungthayaw River. Yaukthwa elongatula sp. nov., a peculiar species, conchologically resembling representatives of the genus Solenaia (Gonideinae) with ultra-elongated shell was found in the Chindwin Basin. Our records highlight that tropical Asia harbors numerous, but still overlooked local endemic lineages of freshwater bivalves, which may be on the brink of extinction due to the high anthropogenic and climate change impacts.

Indonaiarectangularis (Tapparone-Canefri, 1889), comb. nov., a forgotten freshwater mussel species from Myanmar (Bivalvia, Unionidae).

Uniorectangularis Tapparone-Canefri, 1889 is a little-known nominal species of freshwater mussels described from a tributary of the Ayeyarwady River in Myanmar. This taxon was considered a synonym of Gibbosulalaosensis (Lea, 1863), a margaritiferid species. However, the range of Gibbosulalaosensis does not encompass the Ayeyarwady River watershed. Here we re-examine the holotype of Uniorectangularis and provide a conchological re-description of this species. Based on conchological features such as the shell shape, elevated umbo, and the structure of lateral and pseudocardinal teeth, we transfer this taxon to the genus Indonaia Prashad, 1918 and propose I.rectangularis (Tapparone-Canefri, 1889), comb. nov. It appears to be a rare freshwater mussel species with a restricted range, because it has not been found since the original description. Two additional species in this genus are known from Myanmar, i.e. Indonaiaandersoniana (Nevill, 1877) and I.subclathrata (Martens, 1899).

A new genus and two new species of freshwater mussels (Unionidae) from western Indochina.

The systematics of Oriental freshwater mussels (Bivalvia: Unionidae) is poorly known. Here, we present an integrative revision of the genus Trapezoideus Simpson, 1900 to further understanding of freshwater mussel diversity in the region. We demonstrate that Trapezoideus as currently circumscribed is non-monophyletic, with its former species belonging to six other genera, one of which is new to science and described here. We recognize Trapezoideus as a monotypic genus, comprised of the type species, T. foliaceus. Trapezoideus comptus, T. misellus, T. pallegoixi, and T. peninsularis are transferred to the genus Contradens, T. subclathratus is moved to Indonaia, and T. theca is transferred to Lamellidens. Trapezoideus prashadi is found to be a junior synonym of Arcidopsis footei. Trapezoideus dallianus, T. nesemanni, T. panhai, T. peguensis, and two species new to science are placed in Yaukthwa gen. nov. This genus appears to be endemic of the Western Indochina Subregion. The two new species, Yaukthwa paiensis sp. nov. and Y. inlenensis sp. nov., are both endemic to the Salween River basin. Our results highlight that Southeast Asia is a species-rich freshwater mussel diversity hotspot with numerous local endemic species, which are in need of special conservation efforts.

Intraoperative Optical Coherence Tomography-Guided Femtosecond Laser-Assisted Deep Anterior Lamellar Keratoplasty.

PURPOSE: To describe the feasibility and outcomes of intraoperative optical coherence tomography (OCT)-guided, femtosecond laser-assisted deep anterior lamellar keratoplasty in which the lamellar and tunnel cuts were completed by laser. METHODS: The Ziemer Z8 system was used to scan the corneas intraoperatively and guide the stromal lamellar and tunnel cuts created by the laser. Thirty porcine eyes and 3 human cadaver globes were used to evaluate the accuracy of laser-created intrastromal tunnels and the feasibility of achieving big-bubble pneumatic dissection. The tunnel distance above the Descemet membrane (Dt-dm) was set at 100 and 130 µm, and the accuracy of laser cut was assessed by anterior segment OCT and histological sections. Fourteen patients with keratoconus or corneal scars were then included to evaluate the clinical outcomes. RESULTS: The deviation from the targeted Dt-dm was 5.5% to 8.6% and 0.7% to 9.8% for the 100 and 130 µm groups, respectively. The achieved thickness had a significantly and positively strong correlation with the targeted thickness (r = 0.86; P < 0.001). In all cases, the anterior stromal lamella was removed without difficulty, except in the patients with corneal scars in whom some remaining stromal fiber attachments were observed. A type 1 big bubble was successfully achieved in all patients. CONCLUSIONS: We present the accuracy and clinical outcomes of femtosecond laser-assisted, intraoperative OCT-guided deep anterior lamellar keratoplasty, in which controlled lamellar and tunnel cuts at desired depths were performed by laser in one step, and a successful big bubble was achieved.

Discovery of Novaculina myanmarensis sp. nov. (Bivalvia: Pharidae: Pharellinae) closes the freshwater razor clams range disjunction in Southeast Asia.

The razor clam genus Novaculina represents an example of a marine-derived, secondary freshwater group. It was thought to comprise three species: N. gangetica (Ganges and smaller basins in Bangladesh and northwestern Myanmar), N. siamensis (Bang Pakong and Pasak rivers in Thailand and Mekong River in Vietnam), and N. chinensis (lower Yangtze River, China). Here we describe Novaculina myanmarensis sp. nov., an additional species from the Ayeyarwady and Salween basins representing a divergent lineage that appears to be sister to N. gangetica. This new record closes a Novaculina range disjunction between northwestern Myanmar and Thailand. The populations of this novel species share a shallow molecular divergence from each other indicating potential dispersal events between the two distant freshwater basins during the Late Pleistocene. Our ancestral area modeling suggests that the MRCA of Novaculina crown group was a salt-tolerant freshwater species. The recent Novaculina species most likely originated via allopatric speciation. Our findings highlight that generalist estuarine species could have played the role as a source for bivalve expansions into freshwater and that western Indochina is a separate biogeographic subregion, which is clearly distinct from India. A new synonymy is proposed as follows: Pharellinae Stoliczka, 1870 = Novaculininae Ghosh, 1920 syn. nov.

Gender-specific differences in high-risk sexual behaviors among methamphetamine users in Myanmar-China border city, Muse, Myanmar: who is at risk?

BACKGROUND: Methamphetamine (MA) use is a significant public health concern due to its negative effects on health. However, to date, no epidemiological research has examined high-risk sexual behaviors (inconsistent condom use, having multiple sexual partners and having a history of sexually transmitted infections) among MA users. This topic is particularly important in Myanmar, which is recognized as one of the key MA production countries in the Southeast Asia region. Therefore, this study examined factors associated with high-risk sexual behaviors among MA users in Muse city, Myanmar. METHODS: A community-based cross-sectional study was conducted from January to March 2013 in Muse city, Northern Shan State, Myanmar. In total, 1183 MA users (772 male; 411 female) were recruited using respondent-driven sampling and a computer assisted self-interviewing method. Generalized estimating equation models were used to examine factors associated with high-risk sexual behaviors. RESULTS: A large proportion of MA users engaged in high-risk sexual behaviors (inconsistent condom use: males, 90.7%, females, 85.2%; multiple sexual partners: males, 94.2%, females, 47.2%; and history of STIs: males, 55.7%, females, 56.0%). Among males, being a multiple stimulants drug user (adjusted odds ratio [AOR] =1.77; 95% confidence interval [CI] =1.30-2.41) and being a client of sex workers (AOR = 1.41; 95% CI = 1.08-1.83) were risk factors for engaging in high-risk sexual behaviors. Among females, being a migrant worker (AOR = 2.70; 95% CI = 1.86-3.93) and being employed (AOR = 1.57; 95% CI = 1.13-2.18) were risk factors for engaging in high-risk sexual behaviors as well. CONCLUSIONS: High-risk sexual behaviors were particularly pronounced among both male and female MA users. MA prevention programs that reflect gender considerations should be developed to pay more attention to vulnerable populations such as migrants, clients of sex workers, and less educated female MA users.

Promoting community malaria control in rural Myanmar through an active community participation program using the participatory learning approach.

INTRODUCTION: Malaria is prevalent in more than 80% of townships in Myanmar. The National Malaria Control Programme (NMCP) has been implementing community-based malaria control programs nationwide. However, these programs are mostly developed and directed by health authorities, while communities are passively involved. This study aimed to increase community participation in malaria control and promote community malaria control knowledge and practice in rural Myanmar. METHODS: A community-based study, which employed a mixed method approach, collecting data quantitatively and qualitatively, was conducted in two rural villages. The study implemented an active community participation program (ACPP) using the participatory learning approach in a village (ACPP village) but only routine malaria control was given in another village (non-ACPP village). All households with 142 and 96 household representatives from ACPP and non-ACPP villages participated in baseline and endline surveys. The ACPP was evaluated by process and outcome indicators. A spider gram analysis using five process indicators was applied to evaluate the process of the ACPP. Community participation status in malaria control activities and level of community malaria knowledge and practice were determined as outcomes of the ACPP. RESULTS: The spider gram analysis showed that three indicators (needs assessment and planning, leadership and resource mobilization) gained a score of 4, the organization indicator a score of 5 and the management and evaluation indicator a score of 3. The outcome indicators of the program at 6 months showed that the community participation in malaria control activities in the ACPP village had significantly increased (6.9% to 49.3%) (p<0.001). The program promoted community malaria control knowledge and practice in the ACPP village. The mean scores of knowledge, perception, preventive behavior and treatment-seeking behavior were increased significantly, from 3.0 to 5.9 (p<0.001), 20.1 to 21.0 (p<0.001), 3.4 to 4.2 (p<0.001) and 3.1 to 5.6 (p<0.001), respectively. However, no significant change of outcome indicators was found in the non-ACPP village. CONCLUSIONS: The ACPP implemented by community volunteers using the participatory learning approach was feasible in community-based malaria control. This study suggests several features in the ACPP model that may be useful strategies for the implementation of the current NMCP programs in similar rural settings; however, the effect of the ACPP over a longer period to ascertain the impact of such community participation has yet to be further studied.

Gender difference in early initiation of methamphetamine use among current methamphetamine users in Muse, Northern Shan State, Myanmar.

BACKGROUND: Globally, methamphetamine (MA) use is a significant public health concern due to unprecedented health effects of its use. However, gender similarities and differences in early age of MA initiation and its risk factors among current MA users have been understudied in a developing country setting. METHODS: A community-based, cross-sectional study was conducted using a computer assisted self-interviewing program from January to March 2013 in Muse, Northern Shan State, Myanmar. A total of 1362 (775 male and 587 female) self-reported current MA users aged between 18 and 35 years were recruited using respondent-driven sampling. Two gender-stratified multiple logistic regression models (models I and II) were done for analysis. RESULTS: For similarities, 73.0% of males and 60.5% of females initiated MA before their 18th birthday. The early age of MA initiation was positively associated with the reasons and places of the first time MA use among both genders. For differences, males [hazard ratio 1.35; 95% confidence interval, 1.18-1.54] had a significantly higher risk than females to initiate MA at earlier age. Among male users, participants who had bisexual/homosexual preferences were more likely to initiate MA use earlier. In contrast, female users who exchanged sex for money and/or drugs were more likely to initiate MA in earlier age. CONCLUSIONS: More than 60.0% of male and female participants initiated MA use early; however, males initiated use earlier than females. Although similarities were found among both genders, differences found in key risk factors for early age MA initiation suggest that gender-specific, MA prevention programs are urgently needed in Myanmar.

Assessment of HIV testing among young methamphetamine users in Muse, Northern Shan State, Myanmar.

BACKGROUND: Methamphetamine (MA) use has a strong correlation with risky sexual behaviors, and thus may be triggering the growing HIV epidemic in Myanmar. Although methamphetamine use is a serious public health concern, only a few studies have examined HIV testing among young drug users. This study aimed to examine how predisposing, enabling and need factors affect HIV testing among young MA users. METHODS: A cross-sectional study was conducted from January to March 2013 in Muse city in the Northern Shan State of Myanmar. Using a respondent-driven sampling method, 776 MA users aged 18-24 years were recruited. The main outcome of interest was whether participants had ever been tested for HIV. Descriptive statistics and multivariate logistic regression were applied in this study. RESULTS: Approximately 14.7% of young MA users had ever been tested for HIV. Significant positive predictors of HIV testing included predisposing factors such as being a female MA user, having had higher education, and currently living with one's spouse/sexual partner. Significant enabling factors included being employed and having ever visited NGO clinics or met NGO workers. Significant need factors were having ever been diagnosed with an STI and having ever wanted to receive help to stop drug use. CONCLUSIONS: Predisposing, enabling and need factors were significant contributors affecting uptake of HIV testing among young MA users. Integrating HIV testing into STI treatment programs, alongside general expansion of HIV testing services may be effective in increasing HIV testing uptake among young MA users.

Oral cancer in Myanmar: a preliminary survey based on hospital-based cancer registries.

The occurrence of oral cancer is not clearly known in Myanmar, where betel quid chewing habits are widely spread. Since betel quid chewing has been considered to be one of the important causative factors for oral cancer, the circumstantial situation for oral cancer should be investigated in this country. We surveyed oral cancer cases as well as whole body cancers from two cancer registries from Yangon and Mandalay cities, both of which have representative referral hospitals in Myanmar, and we showed that oral cancer stood at the 6th position in males and 10th in females, contributing to 3.5% of whole body cancers. There was a male predominance with a ratio of 2.1:1. Their most frequent site was the tongue, followed by the palate, which was different from that in other countries with betel quid chewing habits. About 90% of male and 44% of female patients had habitual backgrounds of chewing and smoking for more than 15 years. The results revealed for the first time reliable oral cancer frequencies in Myanmar, suggesting that longstanding chewing and smoking habits are etiological backgrounds for oral cancer patients.