Oral Cavity Cancers: Ethnic Differences in Radiotherapy Outcomes in a Majority South Asian Leicester Community

AIMS

Squamous cell carcinoma oral cavity cancers (SCCOCCs) have a higher reported incidence in South Asian countries. We sought to compare presenting stage and outcome by ethnicity in patients with SCCOCC treated with radical radiotherapy in a single centre in the UK.

MATERIALS AND METHODS

All patients with SCCOCC treated with radical radiotherapy at an oncology department in Leicester (UK) between 2011 and 2017 were identified. Baseline demographic, clinical data and 2-year treatment outcomes were reported.

RESULTS

Of the 109 patients included, 40 were South Asian and 59 were non-South Asian. South Asians had significantly poorer 2-year disease-free survival compared with non-South Asians (54.6% versus 73%, P = 0.01).

CONCLUSION

Our analysis suggests that South Asians with SCCOCC have poorer outcomes despite a younger age and similar disease characteristics. Environmental, social factors and differing biology of disease may be responsible and further research is required to inform targeted interventions.

Chinese Oral Cancer Patients' Pain Beliefs: An Application of Leventhal's Common-Sense Model

BACKGROUND

Patients' pain beliefs are the main obstacle to effective pain management. Assessing and correcting negative perceptions is important for improving pain intensity and quality of life of patients with cancer pain.

AIMS

To explore pain beliefs among oral cancer patients using the Common-Sense Model of Self-Regulation as a theoretical framework. The primary components of the model, cognitive representations, emotional representations, and coping responses, were examined.

DESIGN

A qualitative method was used.

SETTINGS

PARTICIPANTS/SUBJECTS:   METHODS: Semi-structured, qualitative, in-depth interviews were conducted with patients newly diagnosed with oral cancer in a tertiary care hospital. The interviews were analyzed using thematic analysis.

RESULTS

Interviews with 15 patients revealed that the pain beliefs of patients with oral cancer included three themes: pain cognitive representations of oral cancer, pain emotional representations of oral cancer, and pain coping responses.

CONCLUSIONS

Negative pain beliefs are common among oral cancer patients. This novel application of the self-regulatory model demonstrates that it can be used to capture the key pain beliefs (i.e., cognitions, emotions, and coping responses) of oral cancer patients within a single, unifying framework.

Racial disparities in the choice of definitive treatment for squamous cell carcinoma of the oral cavity

BACKGROUND

Definitive surgery is recommended for oral cavity squamous cell carcinoma (SCC). The purpose of this study was to present our assessment of the disparities in treatment selection for oral cavity SCC.

METHODS

Non-Hispanic white and non-Hispanic black patients with oral cavity SCC were identified in the National Cancer Database (NCDB). Regression models were used to estimate relative risk (RR) of receiving surgery and absolute difference between non-Hispanic white and non-Hispanic black patients.

RESULTS

There were 82.3% of non-Hispanic white patients who received surgery, compared to 64.2% of non-Hispanic black patients (P < .001). The non-Hispanic black patients were less likely to receive surgery than non-Hispanic white patients (RR 0.87) with an absolute difference of 10.9%. The non-Hispanic black patients were significantly more likely to not be offered surgery (RR 1.42) and to refuse recommended surgery (RR 1.38) but not have a contraindication to surgery (RR 1.17).

CONCLUSION

The non-Hispanic black patients are less likely to receive or be recommended surgery for oral cavity SCC and are more likely to refuse surgery. Further study is needed to identify strategies to close this disparity.

Association between polymorphisms in pre-miRNA genes and risk of oral squamous cell cancer in a Chinese population

Background

MicroRNAs play important roles in the development of human cancers. This case-control study is to evaluate the roles of the polymorphisms in pre-miRNAs on risk of oral cancer in a Chinese population.

Methods

The genotypes of three polymorphisms were determined in 340 patients with oral squamous cell cancer and 340 healthy controls who were frequency matched for age and sex. Odds ratios (ORs) and 95% confidence intervals (95%CIs) were calculated to assess the association. All analyses were performed using the SPSS software. 3.154() 0.001.

Results

For miR-499 rs3746444, individuals carrying homozygous CC genotype had increased risks of oral cancer compared with the homozygous wild TT genotype (adjusted OR was 3.154, 95%CI was 1.555–6.397, P value was 0.001). The C allele of miR-499 rs3746444 was associated with a higher risk of oral cancer with significant odds ratio of 1.453. In the stratified analyses by sex, the associations between miR-499 rs3746444 and miR-146a rs2910164 polymorphisms with the susceptibility of oral squamous cell cancer were significant in males. However, with 1/4 as many subjects there were no significant associations between the three polymorphisms and oral cancer risks in females. The joint effects of miRNA polymorphisms and smoking on the risk of OSCC were analyzed and the results suggested that the association between microRNA genetic variants and OSCC risk was modified by smoking.

Conclusions

These findings suggest that miR-499 rs3746444 and miR-146a rs2910164 polymorphisms may contribute to genetic susceptibility to oral squamous cell cancer.

Oral Melanoacanthoma: A Case Report, a Review of the Literature, and a New Treatment Option

Objectives:

Oral melanoacanthoma is a rare condition that presents as a pigmented, painful lesion, most commonly on the buccal mucosa. Argon plasma coagulation is a new treatment option for benign oral lesions and is hypothesized to be efficacious for this rare mucosal disorder.

Methods:

Treatment of a case and a review of the English-language literature were performed.

Results:

One patient received a diagnosis of oral melanoacanthoma, and argon plasma coagulation treatment resulted in ablation of the lesion with excellent mucosal healing. A review of the literature demonstrated that this lesion is most commonly associated with black (90.9%), adult female (69.7%) patients and is most commonly located on the buccal mucosa (64.7%).

Conclusions:

Oral melanoacanthoma is a rare, benign mucosal lesion that may require surgical intervention for symptomatic relief. Argon plasma coagulation is a relatively safe and effective means of treating this lesion. Argon plasma coagulation treatment may be expanded to include other benign, superficial lesions of the oral mucosa.

Race and sex disparities in long-term survival of oral and oropharyngeal cancer in the United States

PURPOSE

To investigate the effect of race and sex on long-term survival of oral and oropharyngeal cancer.

METHODS

The Surveillance, Epidemiology and End Results database was queried for adult oral and oropharyngeal cancer patients with at least 25-year follow-up. Kaplan-Meier survival curves and cox proportional hazards model were used to identify differences.

RESULTS

Of the 22,162 patients identified, 70.3% were males. Only 8.9% were alive at 25 years post-diagnosis. Black males show the poorest overall and disease-specific survival rates (p < 0.001). After controlling for covariates, Blacks had a 40% higher hazard of mortality compared with Whites (HR 1.40, 95% CI 1.35-1.46), while females had a 9% reduction in mortality risk (HR 0.91, 95% CI 0.88-0.94).

CONCLUSIONS

Overall and disease-specific survival is poor for oral and oropharyngeal cancer patients, and Black men fare worst. This illustrates the need for long-term cancer survival plans incorporating disparity effects in overall cancer outcomes.

Incidence of oral cavity and pharyngeal cancers by anatomical sites in population-based registries in Puerto Rico and the United States of America

OBJECTIVE

Puerto Rico's (PR) epidemiological data on each oral cavity and pharynx cancer (OCPC) site is yet largely unexplored. Our aim was to compare OCPC incidence in PR, by anatomical site, with that of non-Hispanic whites (NHW), non-Hispanic blacks (NHB), and Hispanic (USH) individuals in the USA.

METHODS

Data from the Surveillance Epidemiology and End Results program and the PR Central Cancer Registry were collected and analyzed. Age-standardized rates, percent changes, and standardized rate ratios were estimated with 95% confidence intervals.

RESULTS

Although declining incidence rates were observed for most anatomical sites in most racial/ethnic groups and in both sexes, the incidence of oropharynx cancers slightly increased for cancers in the oropharynx among PR women, both in the base of tongue and soft palate/other oropharynx (p>0.05). The incidence of soft palate/other oropharynx cancers in PR men was about 2.8 times higher than in USH men (p<0.05) and about 1.4 times higher than in NHW men but 21% lower than in NHB men (p>0.05). Significant interactions terms formed with racial/ethnic group and age were shown in various sites. The largest differences between sexes were consistently noted in PR.

CONCLUSION

Further research in PR should assess the effect of the HPV infection, as well as of other risk factors, in OCPC incidence by anatomical site in younger populations. These data could explain more precisely the reasons for the differences observed in this study, particularly among sexes in PR.

Trends and ethnic disparities in oral and oro-pharyngeal cancers in South Africa, 1992-2001

OBJECTIVE

To describe trends in the epidemiology of oral and of oro-pharyngeal (OAP) cancers in South Africa for the atest period available.

METHODS

Data were obtained from the South African pathology-based National Cancer Registry. All new cases of OAP cancers diagnosed and confirmed histologically from 1992 to 2001 are included for the ICD-10 sites C00 to C14, excluding those involving the major salivary glands (C07-C08) and the nasopharynx (C11). OAP cancer incidence is reported by demographics (gender, age, race/ethnicity) and the anatomical sites involved. The analysis on anatomical sites was restricted to squamous cell carcinomas.

RESULTS

Overall, males had a much higher OAP cancer incidence rate (world age-Standardised incidence rate [ASIR] = 7.01/100 000 per year) than females (ASIR = 1.99). However, among Asian/Indian South Africans, OAP cancer incidence was higher among females (ASIR = 4.60) than among males (ASIR = 3.80). OAP cancer, excluding those involving the lip, was highest among Coloureds (ASIR = 5.72) and lowest among Blacks (ASIR = 3.16). OAP cancer incidence was stable overall, but incidence rates increased significantly among Coloured South Africans over the period under review (p < 0.05). Cancer specifically involving the oro-pharyngeal was most common among Coloureds and showed an increasing trend during the period under review.

CONCLUSIONS

Variations in the incidence of OAP cancers by gender, race/ethnicity and anatomic site indicate a need for culturally-targeted reductions in major risk factors, including promoting tobacco cessation and prevention of risky alcohol use. The implications of the role of the human papillomavirus (HPV) in the prevention of squamous cell carcinomas involving the oro-pharyngeal in South Africa require further investigation.

Incidence of oral cancer among South Asians and those of other ethnic groups by sex in West Yorkshire and England, 2001-2006

In 2008 there were 11682 cases of oral cancer in the United Kingdom; this is 16.41/100000 population, and 3.7% of all cancers. Ethnic coding of these data is poor, and so databases were combined to report rates for the incidence of oral cancer in South Asians compared with those among other ethnic groups in West Yorkshire, 2001-2006. A total of 2157 patients with oral cancer were identified in West Yorkshire, 138 of whom were South Asian (6.4%). We analysed them by ethnicity, sex, area in which they lived, and site of cancer. Oral cancer was significantly more common among South Asian women than those from other ethnic groups in England and West Yorkshire, and in England alone it was significantly more common in men of other ethnic groups than those from South Asia. Patients from South Asia were at higher risk of being diagnosed with oral cancer than those of other ethnic groups within West Yorkshire, when data were adjusted for age at diagnosis and sex. In England and in West Yorkshire there was a significantly higher rate of oral cancer among Southern Asian women than among those of other ethnic groups, and men in other ethnic groups had a higher incidence than those from South Asia (England only). The excess of oral cancers gives further weight to the association between smokeless tobacco, smoking, alcohol, and dietary intake by ethnic group. This information is particularly pertinent in areas such as West Yorkshire where there are large groups of Asian people.

Human papilloma virus, herpes simplex virus and epstein barr virus in oral squamous cell carcinoma from eight different countries

Oral squamous cell carcinoma (OSCC) is a major health problem in many parts of the world, and the major causative agents are thought to be the use of alcohol and tobacco. Oncogenic viruses have also been suggested to be involved in OSCC development. This study investigated the prevalence of human papillomaviruses (HPV), herpes simplex virus (HSV) and Epstein-Barr virus (EBV) in 155 OSCC from eight different countries from different ethnic groups, continents and with different socioeconomic backgrounds. 41 A total of OSCCs were diagnosed in the tongue (26%) and 23 in the floor of the mouth (15%); the other 91 OSCCs were diagnosed in other locations (59%). The patients were also investigated regarding the use of alcohol and smoking and smokeless tobacco habits. Tissue samples were obtained from formalin-fixed, paraffin-embedded samples of the OSCC. DNA was extracted and the viral genome was examined by single, nested and semi-nested PCR assays. Sequencing of double-stranded DNA from the PCR product was carried out. Following sequencing of the HPV-, HSV- and EBV-positive PCR products, 100% homology between the sampels was found. Of all the 155 OSCCs examined, 85 (55%) were positive for EBV, 54 (35%) for HPV and 24 (15%) for HSV. The highest prevalence of HPV was seen in Sudan (65%), while HSV (55%) and EBV (80%) were most prevalent in the UK. In 34% (52/155) of all the samples examined, co-infection by two (46/155=30%) or three (6/155=4%) virus specimens was detected. The most frequent double infection was HPV with EBV in 21% (32/155) of all OSCCs. There was a statistically significant higher proportion of samples with HSV (p=0.026) and EBV (p=0.015) in industrialized countries (Sweden, Norway, UK and USA) as compared to developing countries (Sudan, India, Sri Lanka and Yemen). Furthermore, there was a statistically significant higher co-infection of HSV and EBV in samples from industrialized countries (p=0.00031). No firm conclusions could be drawn regarding the relationship between alcohol, tobacco and virus infections. The significance of our findings must be put in relation to other risk factors and these observations warrant further studies to determine the possible role of viral infections and co-infections with HPV, EBV and HSV as risk markers for the development of OSCC.

Functional genetic variants of TGF-β1 and risk of tobacco-related oral carcinoma in high-risk Asian Indians

Transforming growth factor (TGF)-β1, the most abundant isoform of TGF-β have been implicated in various stages of carcinogenesis such as epithelial to mesenchymal transition, enhanced expression of metalloproteases, down-regulation of cellular adhesion molecule, increased tumor motility and angiogenesis as well as local and systemic immunosuppression leading to a more aggressive and metastatic behavior. We assessed the association of TGF-β1 functional genetic polymorphisms at codon 10 (869 T>C) and 25 (915 G>C) of exon 1 in 140 patients with tobacco-related oral squamous cell carcinoma (OSCC) and 120 normal subjects by PCR-RFLP. The frequency of 869 CC genotype and C allele were significantly higher in patients as compared to controls (P(c), 0.024 and 0.0004, respectively) while no significant difference was observed in the frequency of 915 CC genotype and C allele. In logistic regression analysis CC genotype (OR, 3.87; 95% CI, 1.78-8.41) and C allele (OR, 2.20; 95% CI 1.51-3.20) appeared as susceptible while TT genotype and T allele as protective. In addition C(869)-C(915) haplotype with OR of 2.48 at 95% CI, 1.51-4.06 significantly (P=0.0003) increased the risk of tobacco-related OSCC in Asian Indians.

Self-reported ethnicity and genetic ancestry in relation to oral cancer and pre-cancer in Puerto Rico

BACKGROUND

Hispanics are known to be an extremely diverse and genetically admixed ethnic group. The lack of methodologies to control for ethnicity and the unknown admixture in complex study populations of Hispanics has left a gap in understanding certain cancer disparity issues. Incidence rates for oral and pharyngeal cancer (OPC) in Puerto Rico are among the highest in the Western Hemisphere. We conducted an epidemiological study to examine risk and protective factors, in addition to possible genetic susceptibility components, for oral cancer and precancer in Puerto Rico.

METHODOLOGY/PRINCIPAL FINDINGS

We recruited 310 Puerto Rico residents who had been diagnosed with either an incident oral squamous cell carcinoma, oral precancer, or benign oral condition. Participants completed an in-person interview and contributed buccal cells for DNA extraction. ABI Biosystem Taqman™ primer sets were used for genotyping 12 ancestry informative markers (AIMs). Ancestral group estimates were generated using maximum likelihood estimation software (LEADMIX), and additional principal component analysis was carried out to detect population substructures. We used unconditional logistic regression to assess the contribution of ancestry to the risk of being diagnosed with either an oral cancer or precancer while controlling for other potential confounders. The maximum likelihood estimates showed that study participants had a group average ancestry contribution of 69.9% European, 24.5% African, and 5.7% detectable Native American. The African and Indigenous American group estimates were significantly higher than anticipated. Neither self-identified ethnicity nor ancestry markers showed any significant associations with oral cancer/precancer risk in our study.

CONCLUSIONS/SIGNIFICANCE

The application of ancestry informative markers (AIMs), specifically designed for Hispanics, suggests no hidden population substructure is present based on our sampling and provides a viable approach for the evaluation and control of ancestry in future studies involving Hispanic populations.

Feature selection methods for optimizing clinicopathologic input variables in oral cancer prognosis

The incidence of oral cancer is high for those of Indian ethnic origin in Malaysia. Various clinical and pathological data are usually used in oral cancer prognosis. However, due to time, cost and tissue limitations, the number of prognosis variables need to be reduced. In this research, we demonstrated the use of feature selection methods to select a subset of variables that is highly predictive of oral cancer prognosis. The objective is to reduce the number of input variables, thus to identify the key clinicopathologic (input) variables of oral cancer prognosis based on the data collected in the Malaysian scenario. Two feature selection methods, genetic algorithm (wrapper approach) and Pearson's correlation coefficient (filter approach) were implemented and compared with single-input models and a full-input model. The results showed that the reduced models with feature selection method are able to produce more accurate prognosis results than the full-input model and single-input model, with the Pearson's correlation coefficient achieving the most promising results.

Oral cancer risk factors among Mexican American Hispanic adolescents in South Texas

PURPOSE

Tobacco use and alcohol consumption have been identified as the major risk factors for oral and pharyngeal cancers. This study aimed to assess the knowledge, attitudes and beliefs of adolescent high schoolers in South Texas regarding the risk factors and signs for oral cancer and to examine their prevalence of cigarette smoking, use of smokeless tobacco and alcohol consumption.

METHOD

The sample population was drawn from the public school system in Brownsville, Texas. A 39 item self administered questionnaire was completed by 1667 students in four of the five high schools. 95.6% of the students were of Mexican American Hispanic ethnicity.

RESULTS

Modeling with multivariate logistic regression revealed that among current cigarette smokers, regular alcohol use was the strongest associated risk [OR=15.7; 95% CI=10.9-22.5] followed by use of smokeless tobacco [OR=2.4; 95% CI=1.4 4.1]. There was a significantly greater (P<0.001) use of cigarettes, smokeless tobacco and alcohol among the Mexican American males than females.

CONCLUSIONS

This study shows that the overall risk for oral cancer among the Mexican-American adolescent population is high especially among the males, and there is a great need for carefully planned health education and promotion programs for behavior change.

Age-standardized incidence and mortality rates of oral and pharyngeal cancer in Puerto Rico and among Non-Hispanics Whites, Non-Hispanic Blacks, and Hispanics in the USA

BACKGROUND

In the American region, Puerto Rico (PR) has the highest incidence of oral and pharyngeal cancer (OPC), but racial/ethnic differences have never been assessed and compared with other groups in the United States of America (USA). We compared the age-adjusted incidence and mortality rates of OPC between PR and among USA Hispanics (USH), Non-Hispanic Whites (NHW), and Non-Hispanic Blacks (NHB) to assess the burden of this cancer in PR.

METHODS

Analysis of the age-standardized rates (per 100,000) was performed using the direct method with the world standard population (ASR(World)) from 1998-2002. Annual percent change (APC) and Relative Risks (RR) were calculated using the Poisson regression model.

RESULTS

The incidence ASR(World) for men in PR was constant (APC approximately 0.0%), in contrast, a decrease was observed among NHW, NHB, and USH men, although only USH showed statistical significance (APC = -4.9%, p < 0.05). In women, the highest increase in incidence (APC = 5.3%) and the lowest decrease in mortality (APC = -1.4%) was observed in PR. The ratio of the ASR(World) showed that in all racial/ethnic groups, men had approximately 2-4 fold increased incidence and mortality risk of OPC than women (p < 0.05). Men in PR had a higher mortality risk (p < 0.05) of OPC as compared to USH, NHW, and NHB; but among women, PR showed a significant excess of mortality only as compared to USH (est. SRR = 1.82, 95% CI = 1.41, 2.33).

CONCLUSION

The overall higher incidence of OPC in men in PR as compared to USH, NHB, and NHW could be explained by the effect of gene-environment interactions. Meanwhile, the higher mortality from OPC in PR suggests limitations in the health-care access within this population. Further research is warranted to elucidate these findings.

Case-control study of oral and oropharyngeal cancer in whites and genetic variation in eight metabolic enzymes

BACKGROUND

Genetic variation in xenobiotic metabolizing enzymes may explain differing susceptibilities to the cancer causing effects of tobacco and alcohol.

METHODS

We compared 203 oral squamous cell carcinoma cases and 416 controls for single nucleotide polymorphisms (SNPs) in 8 genes (CYP1A1, CYP2E1, MPO, mEH, GSTM1, GSTT1, GSTP1, and NAT2). Except for NAT2, genotype frequencies were similar in the 2 groups. We classified subjects as fast or slow NAT2 acetylators genotyping 13 NAT2 SNPs.

RESULTS

Fast acetylators were overrepresented in cases (53.7%) compared with controls (43.9%; odds ratio (OR) 1.55, 95% confidence interval (CI) 1.08-2.20; p value = .03). Gene-gene interaction testing suggested several cancer-NAT2 associations, with association strongest among persons without a CYP1A1 variant (*2C or *4) allele (OR 1.77, 95% CI 1.20-2.60, p value = .03) or with a variant MPO (463A) allele (OR 2.38, 95% CI 1.34-4.21, p value = .05).

CONCLUSION

These results implicate fast NAT2 acetylation as a risk factor for oral cancer.

Population-based incidence of conjunctival melanoma in various races and ethnic groups and comparison with other melanomas

PURPOSE

To investigate racial and ethnic differences in the incidence of conjunctival melanoma in a large population-based study.

DESIGN

Observational cross-sectional study.

METHODS

Using data from 1992 through 2003 provided by the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program, we calculated age-adjusted incidence rates of conjunctival melanoma in various racial and ethnic groups (Black, American Indian, Asian and Pacific Islander, Hispanic, and non-Hispanic White). In addition, we calculated the standard incidence ratios (risk ratios) and 95% confidence intervals to describe the differences within these racial and ethnic groups.

RESULTS

From 1992 through 2003, there were a total of 168 conjunctival melanomas diagnosed in 13 SEER registries with known racial and ethnic groups. The annual age-adjusted incidence rates (per million population) of conjunctival melanoma was 0.18 (Blacks), 0.17 (American Indians), 0.15 (Asians), 0.33 (Hispanics), and 0.49 (non-Hispanic Whites). The difference in the incidence of conjunctival melanoma between Whites and Blacks or Asians was statistically significant, but was not significant between Blacks and Asians.

CONCLUSIONS

The overall White-to-Black incidence ratio in conjunctival melanoma was 2.6:1, which is much less than that of uveal melanoma (18:1) and cutaneous melanoma (13:1 to 26:1), but is similar to that of mucosal melanoma (2.2:1 to 2.3:1). The cause and significance of this difference of racial and ethnic incidence in various melanomas are discussed.

Oral squamous cell carcinoma incidence by subsite among diverse racial and ethnic populations in California

OBJECTIVE

The aim of this report was to examine the oral cancer incidence by sex, race/ethnicity, and anatomical subsite.

STUDY DESIGN

Data from the California Cancer Registry (CCR) were used to calculate the age-adjusted incidence rates of invasive oral squamous cell carcinoma (OSCC) by sex, race/ethnicity, and anatomical subsite among residents in California during 1988 to 2001.

RESULTS

Although non-Hispanic (NH) black men have the highest overall incidence rate for OSCC, NH whites and NH blacks have similar incidence patterns by subsite, but the male-to-female (M:F) rate ratio is higher among NH blacks. The OSCC incidence rates for Hispanics are much lower than those for NH whites and NH blacks and similar to those of Asians. The Asian ethnic groups display dramatic variations in terms of the subsite-specific incidence rates and M:F rate ratios.

CONCLUSION

The findings illustrate the heterogeneity and complexity of oral cancer by anatomical location and the importance of cultural habits and behavioral factors in the development of oral cancer.

The unclear role of ethnicity in health inequalities: The scenario of oral cancer incidence and survival in the British south Asian population

Previous research has shown that south Asians residing in the south east of England have greater incidence rates of oral cancer than the majority population but little is known as to whether there are also differences in oral cancer survival. We compared the survival from oral cancer in the south Asian population of south-east England relative to the non-south Asian population and, after adjustment for potential confounders, we did not find any evidence of decreased survival. Indeed there was evidence that British south Asian males have significantly better survival than their non-south Asian peers in the south east of England.

Racial disparity in stage at diagnosis and survival among adults with oral cancer in the US

OBJECTIVES

To explore distribution of stage at diagnosis and relative survival rates among US adults with oral cavity cancer in relation to race, and over time.

METHODS

We obtained 1973-2002 oral cancer incidence data from the Surveillance, Epidemiology, and End Results (SEER) Program, and computed proportions for each oral cavity site by stage at diagnosis, tumor size, and 5-year relative survival rates among Whites and Blacks.

RESULTS

A total of 46 855 cases of oral cavity cancer were reported to the SEER registry among adults > or =20 years between 1973 and 2002. African-Americans had a significantly higher proportion of cancer, mainly in the tongue, that had spread to a regional node or to a distant site at diagnosis than Whites: 67% versus 49% of tongue cancers reported from 1973 to 1987 (P < 0.001), and 70% versus 53% of those reported from 1988 to 2002 (P < 0.001). They had a significantly higher proportion of tongue cancer that were >4 cm in diameter at time of diagnosis (59% versus 44%; P < 0.001), and black men in particular experienced lower 5-year relative survival rates than white men, in particular, for tongue cancer (25% versus 43% from 1973 to 1987, and 31% versus 53% from 1988 to 2002).

CONCLUSION

There are significant racial disparities with respect to stage at diagnosis and survival among adults with oral cancer reported to the SEER registry from 1973 to 2002. One possible explanation for the lower survival among Blacks may be a difference in access to, and utilization of, healthcare services.

Oral and pharyngeal cancer incidence and mortality among Hispanics, 1996-2002: the need for ethnoregional studies in cancer research

OBJECTIVES

We investigated whether oral cavity and pharyngeal cancer (OPC) incidence and mortality statistics among Hispanics in New York State differed from those among Hispanics in the United States as a whole.

METHODS

OPC incidence and mortality statistics for 1996-2002 were obtained from the New York State Cancer Registry and compared with national statistics released by the Surveillance, Epidemiology, and End Results (SEER) program for the same period.

RESULTS

Among Hispanic men, OPC incidence rates were approximately 75% and 89% higher in New York State and New York City, respectively, than national rates reported by the SEER program. No notable differences were identified among Hispanic women. Incidence rates among New York State Hispanic men were 16% higher than those of their non-Hispanic White counterparts. The difference was twice as high (32%) among Hispanic men in New York City. Mortality rates among both men and women exhibited patterns similar to the incidence patterns.

CONCLUSIONS

Ethnoregional differences exist in the incidence and mortality rates of OPC in the United States. New York State Hispanic men exhibit much higher incidence and mortality rates than US Hispanics as reported by the SEER program.

Disparities in oral and pharyngeal cancer incidence and mortality among Wisconsin residents, 1999-2002

OBJECTIVE

Compare incidence, mortality, and trends of oral cancer (including the pharynx) in Wisconsin and the United States by race and gender from 1999-2002.

METHODS

Age-adjusted incidence rates were compared using data from the Centers for Disease Control and Prevention (CDC WONDER). Mortality rates were compared using data from the Wisconsin Interactive Statistics on Health (WISH) and CDC US Cancer Statistics.

RESULTS

Incidence rates for oral cancer were higher among males than females in both Wisconsin and the United States. Trends in the incidence rate show the gender disparity has not changed. Furthermore, the incidence rate for African American males is higher in Wisconsin than in the United States. Mortality rates for males were approximately 2 times higher than females in Wisconsin and the United States. Additionally, African American males are more likely than white males to die from this form of cancer, and the likelihood is higher in Wisconsin than in the United States (2.4 versus 1.8, respectively).

CONCLUSION

Racial disparities in oral cancer for African American males are greater in Wisconsin than in the United States. This may result from variation in access to oral health care, tobacco and alcohol use, as well as limited resources in detection and prevention methods. Wisconsin should focus its oral cancer prevention activities on this high-risk group.

Florida adults' oral cancer knowledge and examination experiences

OBJECTIVE

This study assessed awareness of oral cancer, knowledge of its major risk factors and clinical signs, and oral cancer examination experiences among Florida adults aged 40 years and older.

METHODS

A statewide random digit dial, computer assisted telephone survey was conducted in 2002. Data from 1,773 respondents were weighted to permit statewide estimates. Bivariate analyses were used to examine awareness and knowledge of oral cancer. Multiple logistic regression analysis was used to model past-year oral cancer examination experiences of Florida's adults.

RESULTS

In Florida, 15.5% of adults aged 40 years and older had never heard of oral cancer and another 40.3% reportedly knew little or nothing about it. About one-half of adults did not think oral white or red patches or bleeding could indicate oral cancer and 27.6% correctly identified three of oral cancer's major risk factors. After hearing an oral cancer exam described, just 19.5% of adults reported receiving one within the preceding 12 months. Blacks and Hispanics were significantly less likely than non-Hispanic whites to have received a recent oral cancer examination. Persons with low levels of education, those who lacked a regular dentist or source of preventive medical care, and adults who knew few or none of the clinical signs of oral cancer also were less likely to have received a recent oral cancer exam.

CONCLUSIONS

There is widespread lack of awareness and knowledge in Florida regarding oral cancer and low levels of reported examination, particularly among groups experiencing disproportionately high incidence and late stage diagnosis. Increasing awareness of this disease and promoting primary and secondary prevention may help lessen the disease burden in Florida and reduce racial disparities in its outcomes.

Recovery issues for African Americans following treatment of oral cavity/pharynx cancer

Despite the high incidence of oral cavity/pharynx cancer (OCPC) in African Americans, there is little scientific evidence to date that describes the recovery process following treatment of OCPC in this population. Ethnic differences in an array of psychosocial factors, such as emotional regulation styles and social networks, may influence the recovery course with different morbidities and mortality than European Americans. This paper provides an overview of the current literature pertaining to recovery from treatment of OCPC in the African American population.

Incidence rates of oral cancer and oral pre-cancercous lesions in a 6-year follow-up study of a Taiwanese aboriginal community

BACKGROUND

In a previous article, we reported the prevalence rates of oral mucosal lesions in an aboriginal community from an epidemiological survey of oral pre-cancerous lesions.

METHODS

Since 1997, the authors have started regular follow-up of the study population originally investigated. Thus, it has been possible to obtain incidence rates for the various oral pre-cancerous lesions and conditions.

RESULTS

There were 194 persons without any oral lesion in the 1997 screening. During the clinical follow-up investigation and during the analysis of biopsies from pre-cancerous lesions, we discovered six new lesions (including cancer and pre-cancerous lesions) from five participants. All of the five persons were areca/betel quid chewers, and only one mixed areca/betel quid chewing with cigarette smoking habit. The age-standardized incidence rates for quid lesion, oral submucous fibrosis (OSF) and squamous cell carcinoma (SCC) were 267.0, 374.1 and 146.2 per 100,000 person-years, respectively, for areca/betel quid chewers.

CONCLUSIONS

As compared with the rates from India and the general Taiwanese population, the study community encountered a serious problem of oral lesions.

Underserved elderly issues in the United States: burdens of oral and medical health care

The elderly represent approximately 12.4% of the general population (2000 Census), yet their health care expenditure and consumption represent 14% of the total (2003). Although 10% of the elderly had no medical insurance in 2000, 78% had no dental insurance. Elderly Americans' burden of medical care overuse is worsened by their out-of-pocket expenses for oral health, because this is usually not a covered benefit. In underserved communities, the management of the oral health and dental care needs of older Americans approaches negligence.

Oral cancer incidence disparity among ethnic groups on Guam

Although the prevalence of betel nut use among Chamorro residents of Guam is higher than that of other Micronesians residing on the island, the "other Micronesian" ethnic groups have a mouth cancer incidence rate more than double that of Chamorros. The reason for this apparent disparity in rates of mouth cancer incidence may be clarified by future studies focused on the frequency and method of betel nut use among these populations. Another possible explanation for this apparent disparity in cancer incidence rates could be that of migration to Guam for medical treatment.

Psychometric testing of the Impact of Event Scale-Chinese Version (IES-C) in oral cancer patients in Taiwan

GOALS OF WORK

No culturally relevant instrument exists to assess the impact of cancer on patients in Taiwan. Therefore, this two-phase study was undertaken to (1) develop a Chinese version of the Impact of Event Scale (IES), (2) examine its psychometric properties, and (3) use the IES-Chinese version (IES-C) to assess the impact of cancer in newly diagnosed oral cancer patients in Taiwan.

PATIENTS AND METHODS

The psychometric properties of the 15-item IES-C were tested in 106 newly diagnosed oral cancer patients and analyzed by descriptive statistics, test-retest reliability, Pearson's correlation, and principal component analysis.

MAIN RESULTS

The results showed that (1) the IES-C has satisfactory content validity and feasibility; (2) overall internal consistency (Cronbach's alpha) was 0.91 with values of 0.91 and 0.81 for intrusion and avoidance, respectively; (3) overall test-retest reliability (3-day interval) was 0.97; (4) two clearly identified factors explained 55.97% of the variance; (5) satisfactory construct validity was supported by both factor analysis and theoretically supported correlation analysis (significant correlations between the total IES-C and its subscales as well as anxiety and depression); and (6) oral cancer patients had relatively higher IES-C scores than previously reported.

CONCLUSION

These results support the IES-C as an instrument with satisfactory psychometric properties and ease of use in clinical settings. They also suggest that more attention should be paid to the impact on patients of a new diagnosis of oral cancer. Further testing of the IES-C in different cancer populations is suggested to validate its psychometric properties.

CYP17 and tumor necrosis factor-alpha gene polymorphisms are associated with risk of oral cancer in Chinese patients in Taiwan

CONCLUSION

Patients who carry the T/T homozygote of CYP17 C/T gene polymorphism may have a higher risk of developing oral cancer.

OBJECTIVE

Cancer of the oral cavity is the most commonly seen malignancy in Taiwan, and its rising incidence poses a formidable challenge to oncologists. The CYP17 gene encodes P450c17alpha, an enzyme involved in the metabolism of steroid hormones. Tumor necrosis factor-alpha (TNF-alpha) is one of the cytokines produced by macrophages, and its function has been postulated to play a role in cancer formation. We investigated whether polymorphisms of CYP17 and TNF-alpha genes are associated with oral cancer.

MATERIAL AND METHODS

Polymorphisms of CYP17 and TNF-alpha genes were detected by polymerase chain reaction-based restriction analysis in 137 patients with oral cancer and 102 normal controls.

RESULTS

The results for the CYP17 gene revealed a significant difference between oral cancer patients and normal controls (p =0.0063), but there was no significant difference for the TNF-alpha gene (p =0.4753).

Racial Differences in Oral and Pharyngeal Cancer Treatment and Survival in Florida

OBJECTIVE

This study examined racial differences in treatment and survival for blacks and whites in Florida diagnosed with oral or pharyngeal cancer.

METHODS

Data for 21,481 malignancies of the oral cavity or pharynx diagnosed from 1988 to 1998 were derived from the Florida Cancer Data System. Type of cancer treatment was compared by race, stratified by anatomic site and summary stage at diagnosis. Kaplan-Meier survival curves were used to compare survival rates and Cox regression models were used to estimate hazard ratios for race. Covariates included age, sex, census tract income, and treatment.

RESULTS

Stratifying by tumor site and stage, blacks consistently had poorer survival rates than whites. Across tumor stages, blacks with oral cavity cancer were consistently more likely than whites to have received only radiotherapy and less likely to have received cancer-directed surgery. Trends were similar for pharyngeal cancer, although statistically significant only for regional stages. Across site and stage, blacks consistently had elevated hazard ratios (range: 1.20-1.53) relative to whites.

CONCLUSIONS

In Florida, there were racial differences in patient treatment for oral or pharyngeal cancer. Blacks had lower survival rates than whites, but differences in treatment did not entirely account for racial disparities in survival.

Knowledge of oral cancer risk factors among african americans: do nurses have a role?

PURPOSE/OBJECTIVES

To assess the knowledge of oral cancer risk factors among African Americans.

DESIGN

Descriptive; guided by the Patient/Provider/System Theoretical Model for cancer screening.

SETTING

Community-based primary care center in a southern state.

SAMPLE

141 African Americans. The majority was female, had a 12th grade education, and had an income less than 10,000 dollars; 25% were smokers.

METHODS

Participants were asked to identify whether each of 15 factors (i.e., seven risk factors and eight nonrisk factors) increased risk for oral cancer. One point was added for each correct response; therefore, scores could range from 0-15 points. Demographic data were collected.

MAIN RESEARCH VARIABLES

Knowledge of and misconceptions about oral cancer.

FINDINGS

Only six participants correctly identified all of the risk factors. The majority recognized tobacco but was not as aware of the effects of the sun, alcohol, and diet. Many erroneously identified factors such as hot beverages, poor oral hygiene, spicy foods, dentures, and mouthwash as risk factors. Those with higher incomes and those who visited their dentists in the prior year had more knowledge of risk factors. No differences were found in knowledge based on age, gender, education, or smoking status.

CONCLUSIONS

Some patients are less likely to routinely visit a dentist and are less knowledgeable about the risk factors for oral cancer. Many of these risk factors are modifiable; therefore, patients need to be aware of the risks and have access to effective strategies to reduce risk.

IMPLICATIONS FOR NURSING

Assess risk factors, teach risk reduction, and correct misinformation. Refer patients to dental professionals. Develop community outreach to African American men at barbershops and fraternal organizations.

An academic dental center grapples with oral cancer disparities: current collaboration and future opportunities

This article reviews the epidemiology of oral cancer in the United States, explores the complex reasons for its disproportionate burden in minority groups, and describes the efforts of New York University's College of Dentistry to address these oral cancer disparities. These efforts include the development of state and regional consortia and networks, public education and community screening efforts, undergraduate dental curriculum development, professional education, intensive research efforts, and significant dental-medical collaborations. Future directions include the need to develop and assess oral cancer education/awareness programs, specifically customized to the various dental-medical professionals/trainees and to populations at risk. Improving the quality of life of patients during and following treatment for oral cancer is another important area that has great opportunity for dental-medical collaboration.

Oral epithelial dysplasia: clinical characteristics of western European residents

To detail the clinical presentation of oral epithelial dysplasia in a large cohort of residents in western Europe. Descriptive statistical analysis of the data were calculated using chi-square and Fisher's exact tests. Oral epithelial dysplasia manifested typically as a white or mixed red and white lesion on the tongue, buccal mucosa or floor of mouth. The peak age of presentation of oral epithelial dysplasia was the 6th decade. Most clinically detected lesions had only mild oral epithelial dysplasia. Although uncommon, lesions with severe dysplasia were most likely to arise on the floor of mouth or lateral border of tongue. Oral epithelial dysplasia is likely to manifest as a solitary white patch, but it is not possible to accurately predict the likely degree of dysplasia from the clinical features of such lesions.

Oral pre-cancer and the associated risk factors among industrial workers in Japan's overseas enterprises in the UK

BACKGROUND

Screening at industries has been advocated as a method of early detection for cancer. This study describes the prevalence of oral pre-cancerous lesions and other mucosal diseases following oral mucosal screening, and associated risk factors among Japanese industrial workers in the UK.

METHODS

Oral mucosal screening was by invitation at 51 industrial locations in the UK. A self-administered questionnaire was used to record socio-behavioural factors and frequency of daily intake of fruits and vegetables.

RESULTS

Four hundred and eighty-four subjects attended for oral mucosal screening (mean age 39.9 +/- 8.3 years) and their mean period of residence in UK was 5.3 +/- 4.5 years. 63.4% examined were male. 31.3% of males and 26.6% of females smoked daily. The gender differences were striking compared with Japan's national rates. A higher proportion of managerial staff was regular heavy (20+ per day) smokers. The intake of more than five portions per day of vegetables and/or fruits during the weekend was significantly higher in females than in males (P = 0.022). One hundred and six subjects (22%) were detected with oral mucosal lesions, including 16 leukoplakia lesions (3.3%) and three with oral lichen planus (1%). The rate of positive detections was higher in managers (7.5%). Odds ratios were estimated by socio-behavioural variables. Among subjects positive for oral leukoplakia, managers accounted for 68.8% (OR 5.26; 95% CI, 1.24-22.29). 87.5% of subjects detected with oral leukoplakia smoked daily and had done so for the past 10 years (OR 28.40; 95% CI, 5.63-143.28). Though regular alcohol drinking was a common feature among male leukoplakia cases, heavy alcohol misuse was not encountered. None reported an intake of five or more portions of fruits or vegetables.

CONCLUSIONS

The Japanese nationals working in managerial positions in the UK and daily regular smokers in the industries visited were found to be at a high risk of oral pre-cancer. Regular dental/oral check up and tobacco education programmes are encouraged for oral cancer/pre-cancer control in industrial settings.

Racial/ethnic patterns of care for cancers of the oral cavity, pharynx, larynx, sinuses, and salivary glands

BACKGROUND

Among Americans, both incidence and mortality from cancers of the larynx, oral cavity, and pharynx are higher for African Americans than whites and for men than women. In addition, the 5-year survival rates for these sites are significantly lower for African Americans than whites for each disease stage, particularly among African American males. We examine racial/ethnic variation in tumor characteristics, treatment practices, and their relationship to survival for cancers of the oral cavity, pharynx, larynx, nasal cavity and salivary glands.

METHODS

Eligible individuals were age 20 or older and newly diagnosed with a primary invasive cancer of the oral cavity (excluding the lip), pharynx, larynx, sinuses or salivary glands in 1997 reported to one of nine National Cancer Institute's Surveillance Epidemiology and End Results Registries (SEER). Persons meeting the eligibility criteria for each registry were first stratified by race/ethnic group and stage then selected by random sampling within strata.

RESULTS

We found racial/ethnic differences in diagnoses at specific anatomic sites, disease stage and treatment. African Americans less frequently received a cancer directed treatment than both whites and Hispanics and when treated were generally less likely to receive cancer-directed surgery. In multivariate analysis, the receipt of any cancer directed treatment was significantly associated with race and age group. African Americans and Hispanics had poorer, but not significantly so, overall, but not cancer-specific, survival.

CONCLUSION

We found racial differences in the receipt of cancer treatment among patients diagnosed with selected head and neck cancers. We also found a less favorable distribution of stage for African Americans and Hispanics when compared with whites. The differences in stage we noted and the lower rates of oral cancer screening previously reported for these populations suggests that differential rates of early detection may contribute to racial differences in survival and mortality from cancers of the oral cavity and pharynx. Therefore, we conclude that more equitable receipt of cancer treatment along with preventive measures and earlier detection will help reduce racial/ethnic disparities in survival and mortality from cancers of the oral cavity, pharynx and larynx.

Quantifying epidemiologic risk factors using non-parametric regression: model selection remains the greatest challenge

Logistic regression is widely used to estimate relative risks (odds ratios) from case-control studies, but when the study exposure is continuous, standard parametric models may not accurately characterize the exposure-response curve. Semi-parametric generalized linear models provide a useful extension. In these models, the exposure of interest is modelled flexibly using a regression spline or a smoothing spline, while other variables are modelled using conventional methods. When coupled with a model-selection procedure based on minimizing a cross-validation score, this approach provides a non-parametric, objective, and reproducible method to characterize the exposure-response curve by one or several models with a favourable bias-variance trade-off. We applied this approach to case-control data to estimate the dose-response relationship between alcohol consumption and risk of oral cancer among African Americans. We did not find a uniquely 'best' model, but results using linear, cubic, and smoothing splines were consistent: there does not appear to be a risk-free threshold for alcohol consumption vis-à-vis the development of oral cancer. This finding was not apparent using a standard step-function model. In our analysis, the cross-validation curve had a global minimum and also a local minimum. In general, the phenomenon of multiple local minima makes it more difficult to interpret the results, and may present a computational roadblock to non-parametric generalized additive models of multiple continuous exposures. Nonetheless, the semi-parametric approach appears to be a practical advance.

Oral cavity and pharynx cancer incidence rates in the United States, 1975-1998

To identify subgroups of oral cavity and pharynx (OCP) cancers that may be etiologically distinct, we evaluated age-adjusted incidence rates by histologic type, anatomical site, race, and sex using cases diagnosed during 1975-1998 in nine US Surveillance, Epidemiology, and End Results (SEER) program registries. Male/female rate ratios were about one for adenocarcinoma (AC), three or more for squamous cell carcinoma (SCC), and undetermined for Kaposi's sarcoma (KS). Among males, black/white rate ratios exceeded two for cancers of the palate, tonsil, oropharynx, and pyriform sinus, and were less than one only for lip and salivary gland cancers. Among females, rates by race were similar for all oral sites except lip, but rates for each of the pharynx subsites were higher among blacks. Findings suggest that OCP cancers may be separated into SCC of the lip, SCC of the oral cavity, SCC of the pharynx, AC, and KS.

Polymorphism at GSTM1, GSTM3 and GSTT1 gene loci and susceptibility to oral cancer in an Indian population

This study evaluates the influence of genetic polymorphism at GSTM1, GSTM3 and GSTT1 gene loci on oral cancer risk among Indians habituated to the use of, smokeless tobacco, bidi or cigarette. DNA extracted from white blood cells of 297 cancer patients and 450 healthy controls by the proteinase K phenol-chloroform extraction procedure were analyzed by the polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP) analyses. Lifetime tobacco exposure was evaluated as a risk factor in relation to the polymorphism at the GST gene loci using logistic regression analysis. There was no significant difference in the distribution of the GSTM3 and GSTT1 genotypes between oral cancer patients and controls. In contrast, a significant 3-fold increase in risk was seen for patients with the GSTM1 null genotype (age adjusted OR = 3.2, 95% CI 2.4-4.3). The impact of the GSTM1 null genotype on oral cancer risk was also analyzed in separate groups of individuals with different tobacco habits. The odds ratio associated with the GSTM1 null genotype was 3.7 (95% CI 2.0-7.1) in tobacco chewers, 3.7 (5% CI 1.3-7.9) in bidi smokers and 5.7 (95% CI 2.0-16.3) in cigarette smokers. Furthermore, increased lifetime exposure to chewing tobacco appeared to be associated with a 2-fold increase in oral cancer risk in GSTM1 null individuals. The results suggest that the GSTM1 null genotype is a risk factor for development of oral cancer among Indian tobacco habitues.

Racial disparity in survival of patients with squamous cell carcinoma of the oral cavity and pharynx

BACKGROUND

This study was designed to determine if race and age are independent prognostic factors for survival in patients treated for squamous cell carcinoma of the oral cavity and pharynx.

METHODS

Retrospective study.

RESULTS

Out of 909 patients registered, 815 (90%) were white and 94 (10%) were African-American. The median age was 60 years (range 19-93). The African-American patients had a significantly lower 5 year survival rate of 27.6% (95% CI 19.9-38.3) compared with white patients with a survival rate of 52.0% (95% CI 48.7-55.6) (P < 0.001). The greatest racial disparities in survival were observed in patients under 60 years of age [29.2% (95% CI 19.5-43.6) vs 60.9% (95% CI 56.3-66.0) for African-American and white patients, respectively, P < 0.001], and in African-American men compared with white men [20.2% (95% CI 12.6-30.2) vs 51.0% (95% CI 46.7-53.0), P < 0.001]. A multivariate Cox model, stratified according to stage of disease, indicated that race, age, and type of treatment were statistically significant predictors of survival. After adjusting for race and treatment received, African-American patients had a relative risk of dying of 1.61 (95% CI 1.23-2.10) compared with white patients. All patients 60 years of age and older had a higher risk of dying 1.59 (95% CI 1.31-1.92). Compared with surgical treatment alone, radiotherapy and other treatments were both associated with increased risk of dying with respective relative risks of 1.34 (95% CI 1.01-1.76) and 1.94 (95% CI 1.52-1.48).

CONCLUSIONS

African-American patients had poorer survival outcomes, with race and age emerging as significant independent predictors of survival after treatment for oral and pharyngeal cancer, compared with their white counterparts. Primary and secondary prevention programs that target younger patients at high risk might reduce environmental risk factors such as smoking and alcohol consumption, which may play a greater role in the acquired susceptibility for oral and pharyngeal cancer in African-American males.

Cultural and dietary risk factors of oral cancer and precancer--a brief overview

This is an update on cultural and dietary risk factors for oral precancer and cancer. It is an overview on ethnic differences (where possible) and socio-cultural risk factors (tobacco/areca nut/betel quid, alcohol use and dietary factors) in relation to oral precancer and cancer. While studies were from Western countries, India and China, this update also attempts to include and highlight some studies conducted in the Asia-Pacific region.

Transcultural oral health care: 6. The oral health of minority ethnic groups in the United Kingdom--a review

The 1991 census of England and Wales estimated that the minority ethnic population was almost 2.95 million, or 6% of the total population of the UK. The aim of this paper is broadly to describe the oral health status and trends among minority ethnic groups to enable a clearer formulation of strategies to improve their oral health.

Microsatellite alterations in squamous cell carcinoma of the head and neck - clustering of loss of heterozygosity in a distinct subset

Loss of heterozygosity (LOH) and microsatellite instability (MSI) have been recognized as important events in the carcinogenesis of many cancers, including squamous cell carcinoma of head and neck (SCCHN). However, microsatellite alterations have not been documented in SCCHN from Chinese patients. We investigated the frequency and clinical significance of LOH and MSI in 30 SCCHN from Hong Kong Chinese using polymerase chain reaction on 17 microsatellite markers on chromosomes 3p, 4q, 7q, 9p, 17p and 18q. LOH was present in nine tumours (30%) and MSI in four (13%). The incidence of LOH (7/13; 53.8%) in hypopharyngeal-laryngeal cancers was significantly higher than that (2/17; 11.8%) in the oral cancers (P=0.020). LOH was more often detected at the loci on chromosomes 7 and 9. Patients with tumours having LOH had slightly poorer outcome compared with those without, although the differences did not reach statistical significance. Our data show that the incidence of microsatellite alterations in SCCHN from Hong Kong Chinese is low. However, LOH may be one of the genetic mechanisms in the carcinogenesis of a subset of SCCHN (hypopharyngeal-laryngeal cancers).

Ethnicity and oral cancer

Oral squamous-cell carcinoma, the main type of oral cancer, is among the ten most common cancers in the world. The aims of this paper were first, to consider whether there was evidence of marked ethnic variations in the incidence, management, and survival of oral cancer, and then, to review possible explanations for these variations. Evidence from the literature suggests that there is marked, inter-country variation in both the incidence and mortality from oral cancer. There is also growing evidence of intracountry ethnic differences, mostly reported in the UK and USA. These variations among ethnic groups have been attributed mainly to specific risk factors, such as alcohol and tobacco (smoking and smokeless), but dietary factors and the existence of genetic predispositions may also play a part. Variations in access to care services are also an apparent factor. The extent of ethnic differences in oral cancer is masked by the scarcity of information available. Where such data are accessible, there are clear disparities in both incidence and mortality of oral cancer between ethnic groups.