Diet and prevention of oral cancer: strategies for clinical practice

Low vitamin D and high cholesterol facilitate oral carcinogenesis in 4NQO-induced rat models via regulating glycolysis

OBJECTIVES

Diets and nutritional habits are critical during carcinogenic processes, where a diet poor in fruits and vegetables and rich in meat and other foods of animal origin facilitates carcinogenesis. In this study, we aimed at investigating the possible involvement of vitamin D deficiency (VDD) and high cholesterol (HC) together in oral squamous cell carcinoma (OSCC) through modulating glycolysis.

SUBJECTS AND METHODS

We compared total cholesterol, LDL, HDL, triglycerides, LDH, and vitamin D levels of OSCC patients and control individuals. We used GEO datasets for gene set enrichment and 4-nitroquinoline-1-oxide induced in vivo oral carcinogenesis models to investigate contribution of VDD and HC during carcinogenesis via possible modulation of glycolysis.

RESULTS

We found that VDD and HC co-exist in OSCC patients, and deregulation of cholesterol and vitamin D levels results in enrichment of genes related to glycolysis. We, then, demonstrated that VDD and HC on their own and together facilitated the formation of larger tumors in 4NQO-induced in vivo cancer models, which are suppressed by glycolysis inhibition.

CONCLUSION

We reported collaborative contribution of HC and VDD during oral carcinogenesis, which is mainly carried out via altering energy metabolism in tumor cells.

Association between dietary inflammatory index and oral cancer risk: A systematic review and dose–response meta-analysis

Background

Dietary inflammatory index (DII) has been suggested to be associated with oral cancer risk. However, a quantitative comprehensive assessment of the dose–response relationship has not been reported. We performed a meta-analysis to clarify the risk of oral cancer with DII.

Methods

We searched PubMed, Embase, Cochrane Library, and Web of Science databases for relevant articles published up to 1 March 2022. Fixed- or random-effects models were utilized to estimate the pooled odds ratio (OR) of oral cancer with DII, as appropriate. Restricted cubic splines were used to model the dose–response relationship.

Results

We included five case–control studies involving 1,278 cases and 5,137 controls in the meta-analysis. Risk of oral cancer was increased by 135% with the highest versus lowest DII level [OR: 2.35, 95% confidence interval (CI): 1.88–2.94], and 79% with higher versus lower DII level (OR: 1.79, 95% CI: 1.49–2.15). We found no evidence of a nonlinear dose–response association of DII with oral cancer (p_{non-linearity} = 0.752), and the risk was increased by 17% (OR: 1.17, 95% CI: 1.05–1.30) with 1 unit increment in DII score.

Conclusion

This meta-analysis suggested that a higher DII score was associated with increased risk of oral cancer. Therefore, reducing pro-inflammatory components and promoting anti-inflammatory components of diet may be effective in the prevention of oral cancer.

Awareness on oral cancer among patients attending dental school clinics in Brazil

Background

Oral cancer is considered a public health problem worldwide. Dental schools may play an important role in educating patients about oral cancer. This study aimed at evaluating the knowledge of patients attending clinics at two dental schools in Brazil.

Material and Methods

From March 2017 to April 2017, 251 patients who were attending clinics at two dental schools in Recife, Brazil, were included in the study. Patients were contacted in the waiting rooms of the clinic. Each participant completed a self-administered questionnaire, which consists of 21 questions, including socio-demographic and specific information on the disease. Data were analyzed using descriptive statistics, and a chi-square test (with a 5% significance level) was used to assess the correlation between the variables, education and family income and other variables.

Results

Most participants were women (64.9%) with a mean age of 42.72 years. Most participants were knowledgeable about oral cancer and identified tobacco use (48.6%), alcohol consumption (25.1%), and solar radiation (12%) as the primary risk factors for the disease. Only 36.7% of the participants reported having received counselling on oral cancer, of which 18.3% received the information from a dentist. All patients with an income higher than six minimum wages were aware about oral cancer (p = 0.001).

Conclusions

These findings emphasize the importance of educational programs in dental schools as well providing integrated services for patients seeking care at school clinics, including population’s awareness on oral cancer.

Key words:Dental school, knowledge, oral cancer, oral health education, patient education.

Partial Substitution of Glucose with Xylitol Suppressed the Glycolysis and Selectively Inhibited the Proliferation of Oral Cancer Cells

Suitable diet for cancer survivors remains an unresolved challenge. Increased glucose utilization is a hallmark of various cancers. Therefore, alternative carbohydrate supplying normal tissue but retarding cancer growth is needed. This study investigated the effect of sugar alcohols on the proliferation of oral cancer cells compared to nontransformed cells and explored the mechanism. Six oral squamous cell carcinoma (CAL-27, FaDu, SCC4, SCC9, SCC15, and SCC25) and one nontransformed oral keratinocyte (OKF6/TERT2) lines were cultured in media containing 1 mg/ml glucose and 5.8 mg/ml xylitol or sorbitol, yielding equal energy input to control group (4.5 mg/ml glucose). Partial substitution of glucose with sugar alcohols especially xylitol significantly suppressed proliferation of oral cancer but not nontransformed cells. Despite the addition of isocaloric quantities of the sugars, cancer cells exposed to low glucose plus xylitol had retarded ATP generation and decreased activity of phosphofructokinase (PFK), the rate-limiting enzyme in glycolysis. Furthermore, D-xylulose, its key metabolic intermediate, enhanced the anticancer effect of xylitol. These findings suggested a selective anticancer activity of xylitol and the potential mechanism involving inhibition of glucose utilization. Partial substitution of glucose with xylitol may be a proper nutrient for oral cancer survivors, deserving further investigation in animal and clinical settings.

Assessing Oral Cancer Knowledge Among Undergraduate Dental Students in Kuwait University

Lack of general dental practitioner oral cancer knowledge has been shown to be a major factor to delays in referral and treatment. Dentists' competence and confidence in detecting oral cancer may be strongly influenced by their dental school training. Therefore, the aim of this study was to assess dental student's awareness and knowledge of prevention and early detection of oral cancer. Through the use of questionnaires, the students' knowledge of oral cancer risk factors, diagnostic concepts, and clinical care of patients was assessed. An excellent response rate (97.3 %) was observed in this study. Overall, the students' knowledge of diagnostic items was significantly higher (p ≤ 0.001) than their knowledge of risk factors. A high percentage of students identified tobacco (98.6 %) and alcohol (76.7 %) as the principal risk factors and would offer advice regarding modification of these habits (75.3 %). Also, their knowledge of non-risk factors was significantly lower than their knowledge of proven risk factors (p ≤ 0.001). Only one fifth of the students regarded visual inspection to be an effective screening method. Only 32.9 % stated that all suspicious lesions should be biopsied, and as low as 2.7 % had assisted in taking a biopsy. This study highlights the need for a more structured teaching program with greater emphasis on the early signs and risk factors of oral cancer, performing routine oral examination, referral for biopsy, and appropriate early management of suspicious oral lesions.

Association of tea consumption and the risk of oral cancer: a meta-analysis

OBJECTIVES

Epidemiological studies evaluating the association of tea consumption and the risk of oral cancer risk have produced inconsistent results. Thus, we conducted a meta-analysis to assess the relationship between tea consumption and oral cancer risk.

METHODS

Pertinent studies were identified by a search in PubMed, Web of Knowledge and Wan Fang Med Online. The fixed or random effect model was used based on heterogeneity test. Publication bias was estimated using Egger's regression asymmetry test.

RESULTS

Finally, 14 articles with 19 studies comprising 4675 oral cancer cases were included in this meta-analysis. The relative risk (95% confidence interval) of oral cancer for the highest versus the lowest category of tea consumption was 0.853 (0.779-0.934), and the association was significant between oral cancer risk and green tea consumption [0.798 (0.673-0.947)] but not in the black tea consumption [0.953 (0.792-1.146)]. The associations were also significant in Asian and Caucasian.

CONCLUSIONS

Our analysis indicated that tea consumption may have a protective effect on oral cancer, especially in green tea consumption.

Glutathione S-transferase T1 null genotype is associated with oral cancer susceptibility in Asian populations

Though there are many studies assessing the association between glutathione S-transferase T1 (GSTT1) null genotype and oral cancer risk, the association between GSTT1 null genotype and oral cancer in Asian populations is still inconclusive. We performed a meta-analysis of 19 studies including 2,845 cases and 4,295 controls to derive a more precise estimation of the relationship. The pooled odds ratio (OR) with its corresponding 95 % confidence interval (95 % CI) was used to assess the relationship. Meta-analysis of those 19 studies suggested that there was an association between GSTT1 null genotype and elevated risk of oral cancer risk (OR = 1.25, 95 % CI = 1.00-1.56, P = 0.047). Sensitivity analysis by omitting one study at a time showed that the significance of the corresponding pooled ORs was materially altered frequently, indicating that the pooled ORs were not statistically stable. In addition, there was no obvious risk of publication bias in the meta-analysis. Therefore, the present meta-analysis suggests that the GSTT1 null genotype is a risk allele for oral cancer development in Asian populations, but more studies with large sample and well-matched controls are needed to further confirm the finding from the meta-analysis.

Oral squamous cell carcinoma arising around osseointegrated dental implants

PURPOSE

This literature review investigates the occurrence of oral squamous cell carcinoma (OSCC) around osseointegrated dental implants (DI).

METHODS

Databases were searched from 1989 up to and including November 2011. The eligibility criteria were as follows: (1) original studies, (2) clinical studies and case reports, (3) reference lists of the relevant original and review articles, (4) intervention: occurrence of OSSC around osseointegrated DI, and (5) articles published only in English language.

RESULTS

Fourteen studies were included. In nine studies, the dental implant patients with diagnosed OSCC had previously been exposed to cancer. In five studies, the patients presented with a history of habitual tobacco smoking and alcohol consumption.

CONCLUSION

OSCC is more likely to arise around osseointegrated DI in patients with a previous history of cancer. However, the role of other factors including tobacco and alcohol usage cannot be disregarded.