Etiology of oral squamous cell carcinoma

A Case of Syphilis Suspected Preoperatively as a Case of Tongue Cancer

Syphilis is a sexually transmitted disease caused by Treponema pallidum (TP). We report a case of syphilis that was initially suspected as tongue cancer. An 86-year-old man consulted a neighborhood clinic with an approximately one-month history of pain in the right tongue. The result of scraping cytology of the tongue performed at the clinic was classified as class V, squamous cell carcinoma, and the patient was referred to our hospital. Physical examination revealed a mass on the right side of the tongue and a firm cervical mass. Biopsy revealed no evidence of malignancy; however, the imaging findings led to the suspicion of tongue cancer and lymph node metastasis. The results of blood examination revealed that the patient had syphilis, but since the patient showed few other symptoms, we decided to treat the infection after the planned surgery. We performed right partial glossectomy and neck dissection; however, the postoperative histopathology revealed no evidence of malignancy but nonspecific inflammatory changes with TP spirochetes. The incidence of syphilis has increased dramatically around the world, including Japan, during the last 20 years, and it no longer remains a rare disease. Therefore, syphilis should be included in the differential diagnosis of oral or cervical masses.

Comparison of five-year survival rates among patients with oral squamous cell carcinoma with and without association with syphilis: a retrospective case-control study

BACKGROUND

Syphilis is an infectious disease that is at least discussed to be premalignant. This potential, combined with its general pathological impact, raises the question if syphilis increases mortality in oral cancer patients. The aim of the study was to assess if the five-year survival rates among patients suffering from oral squamous cell carcinoma (OSCC) with (cohort I) and without association with syphilis (cohort II) differ.

METHODS

Retrospective clinical data of patients diagnosed with OSCC (International Classification of Diseases [ICD]-10 codes C01-06) within the past 20 years from the access date September 25, 2021 were retrieved from the TriNetX network (TriNetX, Cambridge, Massachusetts, USA) to gain initial cohort 0. Subjects also diagnosed with syphilis (ICD-10 codes A51-53) were assigned to cohort I. Cohort II was comprised of the remaining individuals of cohort 0 by creating a group with the same number of patients as cohort I, and by matching for age and gender. Subsequently, Kaplan-Meier analysis and Cox proportional hazards regression were performed, and risk, odds and hazard ratios were calculated.

RESULTS

Of a total of 73,736 patients in cohort 0, 199 individuals were each assigned to cohort I and II. During the five-year period after tumor diagnosis, 39 and 30 patients in cohort I and II died. The five-year survival probabilities did not significantly differ between the cohorts (I vs. II = 74.19% vs. 75.01%; p = 0.52; Log-Rank test), nor the risk of dying (I vs. II = 19.6% vs. 15.08%; risk difference = 4.52%; p = 0.23). The calculated risk, odds and hazard ratios were 1.3 (95% confidence interval [CI] = 0.84; 2.00), 1.37 (95% CI = 0.81; 2.31) and 1.17 (95% CI = 0.73; 1.88), respectively.

CONCLUSIONS

The obtained results indicate that the survival rate of individuals with OSCC might not be negatively influenced if syphilis is present/associated. However, the results need to be interpreted cautiously due to limitations related to the retrospective approach, especially as data on the tumor staging were not accessible.

TRIAL REGISTRATION

Due to the retrospective nature of the study, no registration was necessary.

Chronic Mucocutaneous Candidiasis in Autoimmune Polyendocrine Syndrome Type 1

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is an autosomal recessive disease caused by mutations in the autoimmune regulator (AIRE) gene, characterized by the clinical triad of chronic mucocutaneous candidiasis (CMC), hypoparathyroidism, and adrenal insufficiency. CMC can be complicated by systemic candidiasis or oral squamous cell carcinoma (SCC), and may lead to death. The role of chronic Candida infection in the etiopathogenesis of oral SCC is unclear. Long-term use of fluconazole has led to the emergence of Candida albicans strains with decreased susceptibility to azoles. CMC is associated with an impaired Th17 cell response; however, it remains unclear whether decreased serum IL-17 and IL-22 levels are related to a defect in cytokine production or to neutralizing autoantibodies resulting from mutations in the AIRE gene.

Screening pathogenic genes in oral squamous cell carcinoma based on the mRNA expression microarray data

Oral squamous cell carcinoma (OSCC) is one of the most common malignancies and its survival rate has barely improved over the past few decades. The purpose of this study was to screen pathogenic genes of OSCC via microarray analysis. The mRNA expression microarray datasets (GSE2280 and GSE3524) were downloaded from the Gene Expression Omnibus (GEO) database. In GSE2280, there were 22 OSCC samples without metastasis and 5 OSCC samples with lymph node metastasis. In GSE3524, there were 16 OSCC samples and 4 normal tissue samples. The differentially expressed genes (DEGs) in OSCC samples with lymph node metastasis compared with those without metastasis (named as DEGs-1), and the DEGs in OSCC samples compared with normal tissue samples (named as DEGs-2), were obtained via limma package. The Database for Annotation, Visualization and Integrated Discovery (DAVID) was used to perform the functional enrichment analyses of DEGs-1 and DEGs-2. The miRNA-gene pairs of overlaps among DEGs were screened out with the TargetScan database, and the miRNA-gene regulated network was constructed by Cytoscape software. A total of 233 and 410 DEGs were identified in the sets of DEGs-1 and DEGs-2, respectively. DEGs-1 were enriched in 188 Gene Ontology (GO) terms and 8 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and DEGs-2 were enriched in 228 GO terms and 6 KEGG pathways. In total, 126 nodes and 135 regulated pairs were involved in the miRNA-gene regulated network. Our study indicated that transglutaminase 2 (TGM2) and Islet 1 (ISL1) may be biomarkers of OSCC and their metastases. Moreover, it provided some potential pathogenic genes (e.g. P2RY2 and RAPGEFL1) in OSCC.

Gene expression profiling signatures for the diagnosis and prevention of oral cavity carcinogenesis-genome-wide analysis using RNA-seq technology

We compared the changes in global gene expression between an early stage (the termination of the carcinogen treatment and prior to the appearance of frank tumors) and a late stage (frank squamous cell carcinoma (SCC)) of tongue carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide (4-NQO) in a mouse model of human oral cavity and esophageal squamous cell carcinoma. Gene ontology and pathway analyses show that increases in “cell cycle progression” and “degradation of basement membrane and ECM pathways” are early events during SCC carcinogenesis and that changes in these pathways are even greater in the actual tumors. Myc, NFκB complex (NFKB1/RELA), and FOS transcription networks are the major transcriptional networks induced in early stage tongue carcinogenesis. Decreases in metabolism pathways, such as in “tricarboxylic acid cycle” and “oxidative phosphorylation”, occurred only in the squamous cell carcinomas and not in the early stages of carcinogenesis. We detected increases in ALDH1A3, PTGS2, and KRT1 transcripts in both the early and late stages of carcinogenesis. The identification of the transcripts and pathways that change at an early stage of carcinogenesis provides potentially useful information for early diagnosis and for prevention strategies for human tongue squamous cell carcinomas.

Thymosin β4 induces proliferation, invasion, and epithelial-to-mesenchymal transition of oral squamous cell carcinoma

The epithelial-to-mesenchymal transition (EMT) plays a vital role in carcinogenesis, invasion, and metastasis of many epithelial tumors including oral squamous cell carcinoma (OSCC), a common malignancy of the head and neck. However, the functional role of the actin-sequestering protein thymosin β4 (Tβ4) in the EMT in OSCCs remains unclear. Thus, we investigated whether overexpression of Tβ4 could induce in vitro tumorigenesis such as cell proliferation and anchorage independency and an EMT-like phenotype in OSCCs. Also, we examined whether it affects invasiveness and cell motility-associated signaling molecules. Tβ4-overexpressing OSCCs, SCC-15_Tβ4 and SCC-25_Tβ4, enhanced cell proliferation and colony formation. In addition, we observed that Tβ4 overexpression induced an EMT-like phenotype, accompanied by a decrease in expression of the epithelial cell marker E-cadherin and an increase in expression of mesenchymal cell markers vimentin and N-cadherin. Also, the expression level of Twist1, an EMT-inducing transcription factor, was significantly enhanced in SCC-15_Tβ4 and SCC-25_Tβ4 cells. Tβ4 overexpression augmented in vitro invasion and MMP-2 activity and enhanced the phosphorylation of paxillin and cortactin and expression of LIMK1. Taken together, these results suggest that Tβ4 overexpression could be one of the causes of tumorigenesis and progression in OSCCs. Further investigation on the Tβ4 molecule would encourage the development of specific targets for cancer treatment.

Nanotechnology-based drug delivery systems for treatment of oral cancer: a review

Oral cancer (oral cavity and oropharynx) is a common and aggressive cancer that invades local tissue, can cause metastasis, and has a high mortality rate. Conventional treatment strategies, such as surgery and chemoradiotherapy, have improved over the past few decades; however, they remain far from optimal. Currently, cancer research is focused on improving cancer diagnosis and treatment methods (oral cavity and oropharynx) nanotechnology, which involves the design, characterization, production, and application of nanoscale drug delivery systems. In medicine, nanotechnologies, such as polymeric nanoparticles, solid lipid nanoparticles, nanostructured lipid carriers, gold nanoparticles, hydrogels, cyclodextrin complexes, and liquid crystals, are promising tools for diagnostic probes and therapeutic devices. The objective of this study is to present a systematic review of nanotechnology-based drug delivery systems for oral cancers.

Combination of bexarotene and the retinoid CD1530 reduces murine oral-cavity carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide

We investigated the effects of bexarotene (a retinoid X receptor agonist), CD1530 (a retinoic acid receptor γ selective agonist), and the combination of these two drugs for the prevention of oral carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide (4-NQO) in a mouse model of human oral-cavity and esophageal squamous-cell carcinoma previously generated in our laboratory. We observed decreased numbers of neoplastic tongue lesions and reduced lesion severity in the 4-NQO plus CD1530 (4N+C) and 4-NQO plus bexarotene plus CD1530 (4N+B+C) groups compared with the 4-NQO group. RNA-Seq analyses showed increases in transcripts in cell proliferation/cell cycle progression pathways in the 4-NQO vs. the untreated group. In addition, β-catenin and matrix metallopeptidase 9 (MMP9) protein levels and reactive oxygen species (ROS), as assessed by 4-hydroxynonenal (4-HNE) staining, were elevated in tongue tissues 17 wk after the termination of the 4-NQO treatment. The 4N+B, 4N+C, and 4N+B+C groups showed dramatically lower levels of β-catenin, MMP9, and 4-HNE staining compared with the 4-NQO group. The major reduction in 4-HNE staining in the retinoid treatment groups suggests a novel mechanism of action, reduction of ROS, by which bexarotene and CD1530 inhibit carcinogenesis.

High concentrations of hexavalent chromium in drinking water alter iron homeostasis in F344 rats and B6C3F1 mice

Hexavalent chromium [Cr(VI)] induces hematological signs of microcytic anemia in rodents. Considering that Cr(VI) can oxidize ferrous (Fe(2+)) to ferric (Fe(3+)) iron, and that only the former is transported across the duodenum, we hypothesize that, at high concentrations, Cr(VI) oxidizes Fe(2+) in the lumen of the small intestine and perturbs iron absorption. Herein we report that 90-day exposure to Cr(VI) in drinking water resulted in dose-dependent decreases in Fe levels in the duodenum, liver, serum, and bone marrow. Toxicogenomic analyses from the duodenum indicate responses consistent with Fe deficiency, including significant induction of divalent metal transporter 1 (DMT1, Slc11a2) and transferrin receptor 1 (TFR1, Tfr1). In addition, at ⩾20mg Cr(VI)/L in drinking water, Cr RBC:plasma ratios in rats were increased and exceeded unity, indicating saturation of reductive capacity and intracellular absorption of Cr(VI) into red blood cells (RBCs). These effects occurred in both species but were generally more severe in rats. These data suggest that high concentrations of Cr(VI) in drinking limit Fe absorption and alter iron homeostasis. Furthermore, some effects observed at high doses in recent Cr(VI) chronic and subchronic bioassays may be explained, at least in part, by iron deficiency and disruption of homeostasis.

Basal stem cells contribute to squamous cell carcinomas in the oral cavity

The cells of origin of oral cavity squamous cell carcinoma (OCSCC) are unknown. We used a cell lineage tracing approach (adult K14-CreER(TAM); ROSA26 mice transiently treated with tamoxifen) to identify and track normal epithelial stem cells (SCs) in mouse tongues by X-gal staining and to determine if these cells become neoplastically transformed by treatment with a carcinogen, 4-nitroquinoline 1-oxide (4-NQO). Here, we show that in normal tongue epithelia, X-gal(+) cells formed thin columns throughout the entire epithelium 12 weeks after tamoxifen treatment, indicating that the basal layer contains long-lived SCs that produce progeny by asymmetric division to maintain homeostasis. Carcinogen treatment results in a ~10-fold reduction in the total number of X-gal(+) clonal cell populations and horizontal expansion of X-gal(+) clonal cell columns, a pattern consistent with symmetric division of some SCs. Finally, X-gal(+) SCs are present in papillomas and invasive OCSCCs, and these long-lived X-gal(+) SCs are the cells of origin of these tumors. Moreover, the resulting 4-NQO-induced tumors are multiclonal. These findings provide insights into the identity of the initiating cells of oral cancer.

Oral cancer diagnostics based on infrared spectral markers and wax physisorption kinetics

Infrared microspectroscopy is an emerging approach for disease analysis owing to its capability for in situ chemical characterization of pathological processes. Synchrotron-based infrared microspectroscopy (SR-IMS) provides ultra-high spatial resolution for profiling biochemical events associated with disease progression. Spectral alterations were observed in cultured oral cells derived from healthy, precancerous, primary, and metastatic cancers. An innovative wax-physisorption-based kinetic FTIR imaging method for the detection of oral precancer and cancer was demonstrated successfully. The approach is based on determining the residual amount of paraffin wax (C(25)H(52)) or beeswax (C(46)H(92)O(2)) on a sample surface after xylene washing. This amount is used as a signpost of the degree of physisorption that altered during malignant transformation. The results of linear discriminant analysis (LDA) of oral cell lines indicated that the methylene (CH(2)) and methyl group (CH(3)) stretching vibrations in the range of 3,000-2,800 cm(-1) have the highest accuracy rate (89.6 %) to discriminate the healthy keratinocytes (NHOK) from cancer cells. The results of wax-physisorption-based FTIR imaging showed a stronger physisorption with beeswax in oral precancerous and cancer cells as compared with that of NHOK, which showed a strong capability with paraffin wax. The infrared kinetic study of oral cavity tissue showed a consistency in the wax physisorption of the cell lines. On the basis of our findings, these results show the potential use of wax-physisorption-based kinetic FTIR imaging for the early screening of oral cancer lesions and the chemical changes during oral carcinogenesis.

Cytotoxicity and chromosome aberrations in normal human oral keratinocytes induced by chemical carcinogens: Comparison of inter-individual variations

Normal human keratinocytes from the oral cavity were cultured in vitro in serum-free medium. Cultures from different individuals were established, and the responses of the cells to different chemicals were compared. The cells, grown at clonal densities, were treated separately with an alkylating agent (N-methyl-N'-nitro-N-nitrosoguanidine; MNNG), two arsenical salts (sodium arsenate or sodium arsenite), sodium fluoride or two polyaromatic hydrocarbons (benzo[a]pyrene or 7,12-dimethylbenz[a]-anthracene). There were no significant differences in the colony-forming efficiencies (22.8 +/- 4.2%) of control (untreated) cells from five different individuals. At selected doses, each of the chemicals reduced the colony-forming efficiencies of the treated cells. The cytotoxicity of most of the chemicals did not differ significantly among cells derived from different individuals, with the exception of sodium arsenate at two doses and sodium fluoride at the highest dose tested. Induction of chromosome aberrations by MNNG, sodium arsenite, sodium arsenate and sodium flouride was analysed with cells derived from up to nine individuals. There was little difference in the inducibilities of chromosome aberrations among cultured keratinocytes from different donors. Treatment of cells from nine donors with one dose of sodium fluoride revealed a statistically significant inter-individual variation. These findings provide a model system to study the effects of carcinogens on the target cells for oral cancers. The results can be compared with findings for cells from other epithelial tissues, since the culture conditions support the growth of keratinocytes regardless of origin. Little inter-individual variation was observed in the response of oral keratinocytes to the chemicals examined.

Overexpression of lecithin:retinol acyltransferase in the epithelial basal layer makes mice more sensitive to oral cavity carcinogenesis induced by a carcinogen

Lecithin:retinol acyltransferase (LRAT) is an enzyme that converts retinol (vitamin A) to retinyl esters. Its expression is often reduced in human cancers, including oral cavity cancers. We investigated the effects of ectopic expression of human lecithin:retinol acyltransferase (LRAT) on murine oral cavity carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide (4-NQO). We targeted human LRAT expression specifically to the basal layer of mouse skin and oral cavity epithelia by using a portion of the human cytokeratin 14 (K14) promoter. High levels of human LRAT transgene transcripts were detected in the tongues and skin of adult transgenic positive (TG+) mice, but not in transgenic negative (TG-) mice. The retinyl ester levels in skin of LRAT TG+ mice were 32% +/- 5.4% greater than those in TG- mice, and topical treatment of the back skin with retinol resulted in greater increases in retinyl esters (from 6.9- to 14.3-fold in different TG+ mice) in TG+ mouse skin than in TG- mouse skin (1.3 fold). While carcinogen (4-NQO) treatment induced multifocal precancerous and cancer lesions in the tongues of both TG positive (n=16) and negative mice (n=22), higher percentages of transgenic positive mice (62.5%) developed more severe tongue lesions (grades 3 and 4) than transgenic negative mice (24.8%) after 4-NQO treatment (p < 0.05). Carcinogen treatment also resulted in greater percentages of transgenic positive mouse tongues with hyperplasia (71.4%), dysplasia (85.7%, p < 0.05), and carcinoma (28.6%) than transgenic negative mouse tongues (53.3%, 46.7%, and 20%, respectively). Moreover, we observed higher cyclooxygenase-2 (Cox-2) and lower RARbeta(2) mRNA levels in TG+ mouse tongues as compared to TG- mouse tongues after 4-NQO treatment (p < 0.05). Taken together, these data show that overexpression of human LRAT specifically in oral basal epithelial cells makes these cells more sensitive to carcinogen induced tumorigenesis.

Oral cancer: a prosthodontic diagnosis

The prosthodontic literature is replete with articles addressing the reconstruction, psychological adaptation, prosthesis success, quality of life, need for careful follow-up, and many other issues related to the patient who has undergone surgery, radiation, and/or chemotherapy for oral malignant neoplasms. However, in the prosthodontic professional literature, there is a paucity of information related to the early diagnosis and referral of lesions that may represent premalignant or malignant neoplasia. This article will describe the rationale, epidemiology, and appearance of oral premalignant and malignant mucosal lesions as well as the state-of-the-art diagnostic tools currently available to prosthodontists to ensure that their patients are diagnosed at the earliest possible time.

Immortalization of normal human gingival keratinocytes and cytological and cytogenetic characterization of the cells

Most in vitro studies of oral carcinogenesis in human cells are carried out with oral keratinocytes immortalized by human papillomavirus type 16 DNA. However, because various etiological factors for oral cancer are known, it is important to establish new human keratinocyte cell lines useful for studying the mechanism of oral carcinogenesis. Normal human gingival keratinocytes in secondary cultures grown in serum-free medium were either transfected with origin (-) SV40 DNA or sequentially transfected with origin (-) SV40 DNA and human c-fos. The transfected cells were continually passaged and analyzed for cytological and cytogenetic characterizations. Four immortal cell lines were grown for over 1100 days in culture and maintained a vigorous growth for over 250 population doublings. They expressed SV40 T antigen, cytokeratins 8 and 18, and E-cadherin, and overexpressed the c-Fos protein. The immortal cell lines had telomerase activity but lacked transformed phenotypes on soft agar or in nude mice. Each cell line had nonrandom chromosomal abnormalities and minisatellite alterations. One of the immortal cell lines, NDUSD-1, retained the capability to deposit calcium, which was also demonstrated in normal human gingival keratinocytes by alizarin red staining, indicating the possibility that NDUSD-1 cells may retain some natural characteristics of normal gingival keratinocytes. Because the oral ectoderm plays an important role in tooth development, these immortal cell lines may be useful in various experimental models for investigations of oral biology and oral carcinogenesis.

Induction of focal epithelial hyperplasia in tongue of young bk6-E6/E7 HPV16 transgenic mice

Squamous cell carcinoma (SCC) of the oral cavity is one of the most common neoplasms in the world. During the past 2 decades, the role of high-risk human papilloma virus (HR-HPV) has been studied and the data supporting HPV as a one of the causative agents in the development and progression of a sub-set of head and neck squamous cell carcinomas (HNSCC) has accumulated. In order to investigate the role of HR-HPV oncogene expression in early epithelial alterations in vivo, we produced transgenic mice expressing HPV16 early region genes from the promoter of the bovine keratin 6 gene (Tg[bK6-E6/E7]). In this article, we demonstrate that E6/E7 transgene was abundantly expressed and cellular proliferation was increased in the middle tongue epithelia of transgenic mice, and that in the same region young (27 weeks old) Tg[bK6-E6/E7] mice spontaneously developed histological alterations, mainly focal epithelial hyperplasia (FEH).

Oral cavity and esophageal carcinogenesis modeled in carcinogen-treated mice

PURPOSE

Squamous cell carcinoma of the oral cavity is one of the most common human neoplasms, and prevention of these carcinomas requires a better understanding of the carcinogenesis process and a model system in which cancer chemoprevention agents can be tested. We have developed a mouse model using the carcinogen 4-nitroquinoline 1-oxide (4-NQO) in the drinking water to induce tumorigenesis in the mouse oral cavity.

EXPERIMENTAL DESIGN

4-NQO was delivered by tongue painting or drinking water to two mouse strains, CBA and C57Bl/6. The incidences of oral cavity carcinogenesis were then compared. In addition, we examined the expression of some of the molecular markers associated with the process of human oral cavity and esophageal carcinogenesis, such as keratin (K) 1, K14, p16, and epidermal growth factor receptor, by immunohistochemistry.

RESULTS

After treatment with 4-NQO in the drinking water, massive tumors were observed on the tongues of both CBA and C57Bl/6 female mice. Pathological analyses indicated that flat squamous dysplasias, exophytic papillary squamous tumors (papillomas), and invasive squamous cell carcinomas were present. Immunohistochemistry analyses showed that 4-NQO changed the expression patterns of the intermediate filament proteins K14 and K1. K14 was expressed in the epithelial suprabasal layers, in addition to the basal layer, in tongues from carcinogen-treated animals. In contrast, control animals expressed K14 only in the basal layer. Moreover, we observed more bromodeoxyuridine staining in the tongue epithelia of 4-NQO-treated mice. Reduced expression of the cell cycle inhibitor, p16, was observed, whereas 4-NQO treatment caused an increase in epidermal growth factor receptor expression in the mouse tongues. Interestingly, similar features of carcinogenesis, including multiple, large (up to 0.5 cm) exophytic papillary squamous tumors and invasive squamous cell carcinomas, increased bromodeoxyuridine staining, and increased K14 expression, were also observed in the esophagi of 4-NQO-treated mice. However, no tumors were observed in the remainder of digestive tract (including the forestomach, intestine, and colon) or in the lungs or livers of 4-NQO-treated mice. These results indicate that this murine 4-NQO-induced oral and esophageal carcinogenesis model simulates many aspects of human oral cavity and esophageal carcinogenesis.

CONCLUSIONS

The availability of this mouse model should permit analysis of oral cavity and esophageal cancer development in various mutant and transgenic mouse strains. This model will also allow testing of cancer chemopreventive drugs in various transgenic mouse strains.

Mutagenicity of the oral carcinogen 4-nitroquinoline-1-oxide in cultured BigBlue rat tongue epithelial cells and fibroblasts

Environmental carcinogen exposures contribute to the development of oral cancer and improved test systems for the analysis of such carcinogens are needed. We have previously isolated and characterized an epithelial cell line from the tongue of a BigBlue rat. Now, we have established an immortalized fibroblast cell line from the same organ. We exposed these cells to 4-nitroquinoline-1-oxide (NQO), a well-known experimental oral carcinogen in the rat and other species, and measured its cytotoxic and genotoxic (cII transgene mutagenesis) effects. Both cell lines were very sensitive to NQO toxicity and showed dose-dependent mutant frequency responses. At the highest NQO dose tested, 70 ng/ml, the mutant frequency was elevated more than eight-fold above background for the epithelial cells and more than 25-fold for the fibroblast cells. We examined cellular parameters which could affect glutathione-dependent detoxication of mutagens. Glutathione (GSH) contents of the two cell lines were similar. Glutathione transferase (GST) activities were measured with several substrates and were generally higher in the epithelial cells. Although multiple biochemical and biological characteristics of individual cell lines are likely to determine responses to mutagens, the greater sensitivity of the fibroblast cells to NQO mutagenicity is in accord with the lower GST activity and the lower DNA content of these cells. These new cell lines are suitable for in vitro testing of chemicals as possible oral mutagens and for studies of their biochemical mechanisms of action.

Nodal metastases from laryngeal carcinoma and their correlation with certain characteristics of the primary tumor

5O cases of carcinoma larynx were included in a prospective study to detect the incidence and pattern of nodal metastases (both clinical and occult) and to study the influence of certain characteristics of the primary tumor on the incidence of nodal metastases. In our study 66% (33 cases) of the lesions were transglottic as compared to 24% (12 cases) supraglottic and 10% (5 cases) glottic lesions. The most common age group affected in our study was 51-60 years comprising 50% of the cases. The most common symptoms were hoarseness, breathlessness and difficulty in swallowing. The incidence of clinically positive neck at the time of presentation was 42% while the incidence of occult nodal metastases was found to be 27.6%. The most common levels of lymph nodes involved in our study were levels II and III (87.5% cases). Multiple level lymph node involvement was seen in 71.4% of the eases at the time of presentation. A high incidence of cervical nodal metastases was associated with the following characteristics of the primary lesion-extralaryngeal spread, infiltrating or endophytic peripheral growth pattern, poor cellular differentiation and advanced T stage. In view of the high incidence of occult nodal metastases, use of selective lateral neck dissection is advocated in patients with a clinically negative neck at the-time of presentation (early glottic carcinomas being excluded).

Loss of heterozygosity on chromosome 7q in in vitro-immortalized human oral keratinocyte cell lines

Loss of heterozygosity in two in vitro-immortalized human oral keratinocyte cell lines was analysed by polymerase chain reaction using 42 polymorphic microsatellite markers on chromosomes 4, 6, 7 and 15. These chromosomes are regarded as candidates for harbouring genes involved in the immortalization of human cells or tumour-suppressor genes in several tumours, including oral cancers, and karyotypic analysis has revealed that both cell lines have non-random alterations in these chromosomes. No allele losses were detected at any informative loci on chromosomes 4 and 6 in the cell lines, including genomic regions adjacent to putative human tumour-suppressor genes and putative senescence genes. When analysed for loss of heterozygosity on chromosomes 7 and 15, allele losses common to both cell lines were detected in the regions at 7q11.2, 7q21.1-21.3 and 7q31.1. High frequencies of loss of heterozygosity on chromosome 7q in at least two distinct regions, particularly centred around 7q31, are observed in a variety of tumours, including oral squamous-cell carcinoma, suggesting that multiple genes involved in immortalization of these cell lines might be present on chromosome 7q.

Potentially malignant and malignant lesions of the lip. Role of silver staining nucleolar organizer regions, proliferating cell nuclear antigen, p53, and c-myc in differentiation and prognosis

The cellular changes leading to carcinoma of the lip are still not completely understood. This study was carried out on 44 malignant and potentially malignant lesions of the lower lip [30 squamous cell carcinomas (SCC), 7 actinic cheilitis, 3 leukoplakias, and 4 nodal metastases from lower lip SCC]. Silver-stained nucleolar organizer regions (AgNORs) and the immunohistochemical expression of proliferating cell nuclear antigen (PCNA), p53, and c-myc were evaluated on formalin-fixed, paraffin-embedded sections. The results indicate that the size and numbers of AgNORs and the percentage of PCNA-positive cells are sensitive parameters for discriminating between potentially malignant lesions and SCC, and for the prognostic sub-typing of lower lip SCC. Furthermore, while p53 positivity was found more frequently in high-grade carcinomas, p53-positive cellular clones were also found in some potentially malignant lesions, a finding probably related to ultraviolet-related cellular damage. These p53-positive lesions could be considered at higher risk of progression to malignancy than the p53-negative ones, although there is no evidence for this as yet. c-myc positivity was found only in some high-grade carcinomas and metastases, and appeared correlated with the later phases of lip carcinogenesis. The combined evaluation of the proliferation status, together with the changes in p53 and c-myc oncoproteins, might constitute useful markers for the prognostic evaluation of potentially malignant, as well as malignant, lesions of the lip.

Dental factors in the genesis of squamous cell carcinoma of the oral cavity

This study investigated the role of dental factors in the genesis of squamous cell carcinomas of the oral cavity. 99 newly diagnosed patients with advanced head and neck cancer were evaluated for potential demographic, dental and prosthetic risk factors. Patients with extra-oral malignancies were used as controls in the analysis of dental factors in patients with intra-oral cancers. We performed multiple comparisons of these factors against the primary tumour sites. An analysis of dental and prosthetic factors and patients with intra-oral versus extra-oral tumours revealed no significant differences. However, all 28 intra-oral malignancies arose in areas in contact with teeth and/or appliances. For example, all 10 oral tongue lesions arose on the lateral borders and all six floor of (drop) mouth primary tumours developed at the flange extension of a lower denture. Patients with partial or full dentures had significantly lower node (N) scores than patients without a prosthesis. Although this paper suggests a relationship between dental factors and the genesis of oral squamous cell malignancies, a larger prospective study would be required to achieve definitive data. Patients at risk should be followed carefully for the development of chronic irritation from teeth and appliances.

Immunohistochemical detection of p53 in non-malignant and malignant oral lesions associated with snuff dipping in the Sudan and Sweden

Immunohistochemistry was used to examine the expression of p53 in pre-malignant oral lesions and oral squamous-cell carcinomas (SCCs) from Swedish and Sudanese snuff-dippers, as well as in pre-malignant oral lesions and oral SCCs from non-snuff-dippers from the Sudan, Sweden and Norway. Of the 14 SCCs from Sudanese snuff-dippers, 21% (3/14) expressed p53. Of the 14, 60 and 41 SCCs from non-snuff-dippers from the Sudan, Sweden and Norway, 64% (9/14), 65% (39/60) and 68% (28/41) expressed p53, respectively. A statistically significant difference in expression of p53 was found in SCCs from Sudanese snuff-dippers compared to those from non-snuff-dippers from all/or any of the 3 countries. None of the suspected pre-malignant oral lesions from Sudanese snuff dippers or non-snuff-dippers expressed p53. Only 2 out of the 15 oral fibro-epithelial hyperplastic lesions from Swedish snuff-dippers expressed p53. Some of the oral epithelial dysplastic lesions, as well as the carcinoma in situ lesions from Norwegian non-snuff-dippers, expressed p53, while the oral fibro-epithelial hyperplastic lesions did not. The low relative frequency of p53 expression found in oral SCCs from snuff-dippers compared to those from non-snuff-dippers might suggest differences in mechanisms of oncogenic action induced by snuff. Alternatively, the pathogenesis of malignant oral lesions from snuff-dippers may follow a p53-independent pathway. In view of the unusually high levels of the tobacco-specific nitrosamines (TSNA) found in the type of snuff used in the Sudan, investigations of p53 mutations or oncogenes are needed.

Prevalence and related risk factors of betel quid chewing by adolescent students in southern Taiwan

The prevalence and related risk factors of betel quid chewing among adolescent students were studied in a junior high school (group 1) and in a vocational school (group 2) in southern Taiwan. Group 1 consisted of 3548 participants (89.7% response rate) and group 2 of 1358 (97.6% response rate). The students were asked to complete a questionnaire anonymously. In the junior high school 1.9% of students including all grades (13-15 years old) and both sexes was found to be a current betel quid chewer and 14% was an ex-chewer, whereas 10.2% of vocational school students (16-18 years old) was a current chewer and 31% was an ex-chewer. The prevalence of betel chewing was significantly higher among boys than girls. A high proportion of chewers was also a smoker and alcohol drinker. A statistical analysis of sociodemographic factors showed that male students who smoked tobacco, consumed alcohol and were friends or classmates of students who were betel quid chewers, were the likeliest adolescents to chew betel quid.

Screening for syphilis in patients with carcinoma of the tongue

The oral signs of syphilis have been comprehensively described and can be identified at each stage of the infection. Despite the historical recognition that inadequately treated or untreated syphilitic leukoplakia may undergo malignant transformation, many surgical units no longer routinely screen patients presenting with malignant or premalignant lesions. In this study, five of the 63 patients (8%) who presented with neoplasms of the tongue reacted to syphilis antibodies. These results indicate that syphilis is still prevalent in this group of patients and suggest that serological investigations may be warranted in the initial assessment of all patients with oral cancer.

Preliminary assessment of the epithelial nuclear-cytoplasmic ratio and nuclear volume density in human palatal lesions

We have analysed both the nuclear-cytoplasmic (N/C) ratio and nuclear volume densities (VVN) in defined strata from human hard palate lesions with and without malignant potential to determine the prognostic reliability and/or validity of this parameter. Measurements of cellular and nuclear areas of basal and spinous cells from normal (N) and pathological palatal epithelium were made on histological sections using an image analyser. The lesions comprised fibrous hyperplasia (FH), traumatic inflammation (INF), benign hyperkeratosis (HK), squamous cell papilloma (PP), dysplastic epithelium adjacent to invasive carcinoma (CE) and islands of invasive squamous cell carcinoma (CI). In basal cells, no significant differences were detected in comparisons of N/C and VVN between all pathological groups and the N control group. The mean value for CE was lower than that obtained for N. In spinous cells, the only statistically significant comparison was between IF and FH for both N/C and VVN. Both parameters were lower in CE than in N. Of all groups analysed except CI, the CE group is the only one likely to possess an increased malignant potential. The N/C ratio therefore seems to be of no value as a predictor of malignancy in palatal epithelial lesions.

Case-control study of squamous cell cancer of the oral cavity in Denmark

A population-based case-control study was designed to examine if the risk of developing intra-oral squamous-cell carcinoma in Denmark was associated with occupation, marital status, residence, dental status, and exposure to coffee, tea, tobacco, and alcohol. Cases consisted of 161 consecutively-admitted incident patients with histologically verified, primary, intra-oral squamous-cell carcinoma treated at the Aarhus University Hospital from January 1986 to November 1990. For each case, three controls of the same gender and age were selected randomly from among nonhospitalized residents in the hospital's catchment area (some 1.4 m inhabitants). Four hundred of the selected 483 controls participated in the study. Risk was associated significantly with marital status, residence, dental status, alcohol consumption, and exposure to tobacco. When correcting for tobacco and alcohol consumption, only marital status and dental status remained significant. The association between risk and marital status was particularly prominent among divorced compared with married persons (odds ratio [OR] = 2.3, 95 percent confidence interval [CI] = 1.1-4.6). Persons with less than five teeth had an OR of 2.4 (CI 1.3-4.1) compared with persons with 15 or more teeth. Tobacco and alcohol exposure were the strongest individual risk-indicators in both lifetime and current consumption estimates, and their composite effect was particularly strong. Compared with nonusers, OR for tobacco (> 20 g/d) adjusted for alcohol = 5.8 (CI = 3.1-10.9); OR for alcohol (> 5 drinks/d) adjusted for tobacco = 8.4 (CI = 4.0-17.6). The OR for heavy users of tobacco and alcohol (> 20 g tobacco/d and > 5 drinks/d) was 80.7 (CI = 21.8-298.8). These results confirm that tobacco and alcohol contribute significantly to the risk of developing oral cancer. There were no significant differences between the risk estimates for the two genders or young and old persons. Two simulation studies indicate that the observed risk associated with tobacco and alcohol consumption cannot be explained reasonably by a high consumption among the 83 nonrespondents.

Prognostic factors in oral cavity carcinomas

This retrospective study of 176 patients with oral cavity carcinoma showed that nearly 60% of the patients presented with an advanced stage of disease. The duration of symptoms was shorter in patients with a large tumour than with a small (p less than 0.001) and in patients with metastases than in those without (p less than 0.01). Lymph node metastases were more common in large tumours (p less than 0.01), in tumours with high malignancy grading (p less than 0.05) and in non-diploid tumours (p less than 0.001). The presence of lymph node metastases (p less than 0.001), tumour size (p less than 0.01) and tumour DNA ploidy (p less than 0.005) were the only parameters that significantly influenced survival (Cox regression analysis).

Candidal infection in oral lichen planus

The prevalence of candidal infection in lichen planus (LP) and its possible association with ulceration were independently examined in two archived series of 108 and 77 cases derived from two separate populations. To ensure that similar material was being compared, each case was histopathologically reassessed and confirmed as LP or reclassified as nonspecific lichenoid stomatitis (NSLS), lichenoid dysplasia (LD), or other (O). Three further sections, cut at 25 microns intervals, were stained with periodic acid-Schiff reagent for the identification of intraepithelial candidal pseudohyphae. As control specimens, 61 normal and 59 hyperkeratotic mucosal samples were similarly processed and examined. Candidal infection was found in 17.4% and 16.4% of ulcerated and nonulcerated LP cases, respectively, and in 40.0% and 16.7% of ulcerated and nonulcerated NSLS cases, respectively. One case of LD was infected. Each control series contained one infected case. The results indicate that candidal infection occurs more readily in LP and NSLS, with no apparent association with ulceration in LP. The comparatively marked increase in the infection prevalence of ulcerated NSLS cannot be statistically confirmed, and its significance remains uncertain.

A relationship found between intra-oral sites of 4NQO reductase activity and chemical carcinogenesis

Topical application on rat oral mucosa of the chemical 4-nitroquinoline 1-oxide (4NQO) has been shown to produce squamous cell carcinomas on the posterior tongue and/or the posterior hard palate. 4NQO is broken down in vivo by a diaphorase, 4NQO reductase (E.C.1.6.99.2), to produce an active molecule believed to be responsible for carcinogenesis. It has been shown that there are higher concentrations of 4NQO reductase in oesophageal mucosa compared with elsewhere in the gastrointestinal tract. The purpose of these experiments was to compare the distribution of certain diaphorases in the oral mucosa. Samples of rat tongue and cheek epithelia were homogenized, then ultracentrifuged to provide mixed cytosol and microsome fractions from the epithelial cells. A spectrophotometer was used to measure the variation in absorbance at 340 nm of NADH consumed by reduction of 4NQO by enzymes present in the tissue extracts. A histochemical technique was used to compare the activity of NADH diaphorase, NADP diaphorase and glucose-6-phosphate dehydrogenase at different sites of the oral mucosa. Statistical analysis showed that there were significant (P less than 0.01) differences between the activities of all three enzymes at different sites of the oral mucosa. In each case, a higher activity was found at the sites of high incidence of squamous cell carcinoma. A lower activity was found at sites where carcinomas did not occur.

Oral cancer

In the U.S. oral cancer accounts for 2.1% of all cancers and 1% of cancer deaths. Two to three times as many males as females are affected. Blacks have more intra-oral cancer than whites, and their incidence and mortality rates have increased in recent years. The etiologic process very likely involves several factors. The major etiologic agents are tobacco (all types) and alcoholic beverages. Herpes simplex virus, human papilloma virus, and Candida have been implicated. Host factors include poor state of dentition, nutritional aberrations, cirrhosis of liver, lichen planus, and immunologic impairmant. Cellular changes include amplification of some oncogenes, alterations in antigen expression, production of gamma-glutamyl transpeptidase, and disturbance of keratin and involucrin production. Experimentally, cancer is readily produced on the hamster cheek pouch and rat oral mucosa. Unlike oral cancer in humans, most experimental lesions are exophytic, and they rarely metastasize.

Squamous cell carcinoma of the oral cavity. A review of 176 cases with application of malignancy grading and DNA measurements

This retrospective study comprised 176 patients with squamous cell carcinoma of the oral cavity treated at The Linköping University Hospital over a 19-year period. Clinical parameters, microscopic malignancy grading (according to Jakobsson et al. and Glanz and Eichhorn), DNA cytofluorometry, analysis of therapeutic modalities and statistics regarding survival and prognosis are reported. The mean age was 70 years with a male: female ratio of 1.3:1 One hundred and four patients had T1 or T2 tumours and 109 an N0 neck. Cervical lymph node metastases were more frequent in patients with larger tumours (T3 + T4) than in those with smaller (T1 + T2) (P less than 0.01), in tumours with a high malignancy grading compared to those with a low (P less than 0.05) and in DNA non-diploid tumours compared to diploid ones (P less than 0.001). The aneuploid tumours responded better to preoperative radiotherapy than did diploid (P less than 0.01) or polyploid (P less than 0.05) tumours. Eighty-nine per cent of the recurrences occurred within 1 year of initial therapy. Secondary treatment was successful in 15 of 37 (41%) patients in whom the tumour recurred either at the primary site or in regional lymph nodes, but only in 1 of 8 (12%) with recurrences in both locations. Surgery alone or combined with radiotherapy resulted in equivalent survival rates for tumours in stages I and II. In advanced stages combined radiotherapy and surgery gave better survival figures than either modality alone (P less than 0.01; Kaplan-Meier). The presence of lymph node metastases (P less than 0.001), tumour size (P less than 0.01) and tumour ploidy (P less than 0.005) were the only clinical and histological parameters that significantly influenced survival (Cox regression analysis). Twenty-four patients developed a secondary primary malignancy; 21 of these were located in the aerodigestive tract.

Environmental diseases of the digestive system

Environmental factors are important mediators of many diseases of the digestive system, defined as the alimentary tract and the accessory organs of digestion, the liver and pancreas. In this review, we principally focus on the action of chemical agents which are classified as (1) naturally occurring compounds, (2) occupational hazards, (3) therapeutic drugs, and (4) constituents of substances of abuse. In addition, the putative role of dietary habits in the pathogenesis of malignant diseases of the digestive system is discussed.

Induction of oral cancer by 7,12-dimethylbenz[a]anthracene in rats with liver cirrhosis

The effects of carbon tetrachloride-induced liver cirrhosis and xerostomia on oral carcinogenesis were studied in rats given the lipid-soluble carcinogen 7,12-dimethylbenz-[a]anthracene (DMBA). The first carcinoma was detected after only 1 month of DMBA applications. After a further 8 months 85% of the animals had developed one or more squamous cell carcinomas. The latency period for DMBA-induced oral cancer in cirrhotic rats with xerostomia was markedly reduced in comparison with previous findings from xerostomic rats without liver cirrhosis. The results support earlier epidemiologic studies indicating a relationship between liver cirrhosis and oral cancer.

Human papilloma virus (HPV) and carcinomas of the head and neck

Increasing evidence for a causal link between human papilloma virus and carcinomas of the cervix has emerged in recent research. This group of species-specific, epitheliotropic viruses has also been associated with tumours of the head and neck, but the individual reports deal only with relatively small sample numbers. In the present review these reports are considered in relation to the methods employed, and it is concluded that HPV is associated with more than 50% of oral and nasal carcinomas, as well as with carcinomas of the larynx and oesophagus. The clinical relevance and strategies for future work are outlined.

Squamous cell carcinoma of the upper aero-digestive tract in women

Between 1970 and 1985, 95 women presenting carcinomas of the oral cavity, pharynx or larynx, were treated at the Institut Jean-Godinot. Classification of these patients according to age shows a bimodal curve and the existence of two different populations. The main difference between groups appears to be the existence or not of tobacco intoxication. According to this criteria, the two groups of patients are statistically different in mean age (nonusers 16 years older than users, p less than 0.01) and in the site of the primary, with an excess of carcinomas of the oral cavity in the nonusers group (p less than 0.01). In contrast, no difference was found in the locoregional extension of the tumor (TNM), in the modalities and result of treatment or in the evolution and survival of patients.

Oral cancer after surgery for peptic ulcer

Oral cancer was studied in a population of 3435 which constituted all persons who were operated upon because of peptic ulcer in Gothenburg 1952-61. This population formed a data base which was coordinated with the National Cancer Register and the Register of Causes of Deaths in Sweden. The expected number of oral cancers was 7.7 and the observed number was 17 (P less than 0.01). In gerontologic population studies of the elderly in Gothenburg it was shown that 70-yr-old men with a history of peptic ulcer surgery more often were tobacco smokers, edentulous and more often had sideropenic and megaloblastic anemia and also had a lower bone mineral content.

An interpretative review of smokeless tobacco research in the United States: Part I

The first part of a two-part series reviewing the published literature of smokeless tobacco in the United States and concomitant health effects associated with its use. This article delineates the current status of its prevalence, behavioral psychosocial factors associated with use, and review of the negative health effects associated with regular use.

Precancerous and other oral mucosal lesions related to chewing, smoking and drinking habits in Thailand

In a field study (1979-1984) four out of six major hilltribes of Northern Thailand, namely the Lahu, Karen, Lisu and Meo, as well as a group of rural Thai, were examined. Chewing, smoking and drinking habits and lesions of the oral mucosa (leukoedema, preleukoplakia, leukoplakia and chewer's mucosa) were recorded. 1866 individuals were examined. Considerable differences in the chewing and smoking habits among the various tribes were recorded and some of them were considered tribe-specific. Chewing of betel and miang was more prevalent among older people; these habits seem to have lost their attraction for the younger people. Cigarette smoking was more prevalent among middle-aged individuals. Leukoedema was observed in 12.4%, preleukoplakia in 1.8%, leukoplakia in 1.1% and chewer's mucosa in 13.1%. Men and the older generation were affected more often, except that more women (Karen and Thai) revealed chewer's mucosa. A positive correlation could be demonstrated between some mucosal lesions (leukoedema, chewer's mucosa) and some smoking and chewing habits.

Implications of Smokeless Tobacco Use Among Athletes

In brief: This literature review delineates the current status of smokeless tobacco. It discusses the prevalence and terminology as well as periodontal effects, buccal mucosal and soft-tissue alterations, leukoplakia, cancer, carcinogenic components, hemodynamic alterations, and potential addiction. It is clear that physicians and dentists should discourage their patients from using smokeless tobacco. Young people particularly may be influenced by popular sports figures and celebrities who convey the erroneous impression that smokeless tobacco is harmless.

Oral cancer detection. The importance of routine screening for prolongation of survival

The incidence of oral cancer has increased in the past ten years. Early diagnosis and treatment are essential to long-term survival; however, patients at highest risk visit the dentist infrequently. The reddish, velvety or erythroplakial lesion at the base of the tongue or floor of the mouth is highly suspicious in any patient and requires further evaluation. High-risk patients with less suspicious appearing lesions must be reevaluated on close recall. Prognosis improves vastly when the lesion is detected and treated early. One study demonstrated a 64% five-year survival rate for patients with oral cancer that was diagnosed before regional lymph node involvement versus a 15% five-year survival for patients whose lesions were diagnosed after regional lymph node involvement. By including an oral cancer examination in routine physical examination of patients, the physician and public health nurse can increase the likelihood of early detection of oral cancer.

Detection of papillomavirus DNA in oral papillomas and carcinomas: application of in situ hybridization with biotinylated HPV 16 probes

Four oral papillomas and 7 carcinomas were studied for the presence of HPV DNA by means of in situ hybridization. Hybridization was carried out with a HPV 16 probe labelled with biotin under different conditions (nick translation/photobiotin). Subsequently, a modified biotin-avidin-alkaline phosphatase procedure was used to visualize virus infected cells. Four/4 papillomas and 4/7 carcinomas were seen to contain HPV harbouring cells. Positive cells were located at intermediate and superficial cell layers in papillomas and in keratinized zones in carcinomas. Analogous results were found with nick translated and photobiotinylated probes. DNA-biotinylation in conjunction with the biotin-avidin-alkaline phosphatase detection system proved to be a sensitive, convenient and rapid modification of in situ hybridization.

Changing trends of tobacco use in a teenage population in western Pennsylvania

Information on tobacco use was obtained from an anonymous questionnaire distributed to 609 8th, 9th, and 10th grade students in the Pittsburgh area. The data disclosed that 22 per cent of the girls and 11 per cent of the boys were smoking. However, 35 per cent of the young men reported using smokeless tobacco; snuff dipping (6 per cent), tobacco chewing (10 per cent), and snuff and/or tobacco chewing (19 per cent).

Patterns of smokeless tobacco use in a population of high school students

We assessed the prevalence of smokeless tobacco use by 901 high school students in two Arkansas communities, and identified factors associated with initiation and maintenance. Results showed that 36.7 per cent of males and 2.2 per cent of females currently used smokeless tobacco. Modal responses indicated that if smokeless tobacco was used at all, it was used with frequency on an almost daily basis. Health professionals need to monitor this phenomenon closely and take appropriate preventive actions.