Multiple logistic regression analysis predicts cancer risk among tobacco usage with glutathione S-transferase p1 genotyping in patients with head and neck cancer

INTRODUCTION

Numerous studies have been investigated to understand the association between glutathione S-transferase P1 (GSTP1) polymorphism and risk of head and neck cancer (HNC) but yielded contradictory results, and no studies could confirm polymorphism in GSTP1 and that tobacco usage increases the risk of HNCs. Therefore, this study aimed to understand the association of GSTP1 Ile105Val polymorphism with or without tobacco usage in carcinogenesis and clinicopathological characteristics of patients with HNC.

MATERIALS AND METHODS

Binary logistic regression analysis was performed to predict HNC risk with tobacco use and GSTP1 genotyping. Five predictor variables such as gender, age, tobacco usage, familial, and GSTP1 genotypes were included in the model.

RESULTS

The results of the logistic regression analysis show that the full model which considered all the five independent variables together was statistically significant, log-likelihood = -111.820, and all slopes are zero: G = 74.297, degree of freedom (DF) = 5, P = 0.000. The strongest predictor in this model is tobacco usage (odds ratio = Z = -5.16, P = 0.000).

CONCLUSION

The study concludes that multiple logistic regression analysis model could predict the risk factors in case-control studies where control samples are compromised.

DNA repair and mutagen sensitivity of epithelial cells and lymphocytes in oropharyngeal cancer

Tobacco-associated nitrosamines are known carcinogens causing DNA damage in epithelial cells of the head and neck. A matched case-control study was performed to evaluate the sensitivity of patients with squamous cell cancer (SCC) of the oropharynx, and controls to tobacco-associated nitrosamines. Quantitative DNA repair was evaluated following a period of 15 and 30 min. Fresh biopsies from 100 male donors of macroscopically healthy oropharyngeal cells and lymphocytes (50 SCC patients and 50 controls) were incubated with N-nitrosodiethylamine (NDEA), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) or N-nitrosonornicotine (NNN). DNA damage in epithelial cells and lymphocytes was assessed using the comet assay. Following incubation with NDEA, cells underwent a period of DNA repair. All of the nitrosamines caused equivalent genotoxic damage in mucosal cells and lymphocytes of the two groups. Lymphocyte DNA repair capacity in the control group (26.8 and 37.1% after 15 and 30 min) was comparable to the tumor group (23.6 and 40.6%). However, epithelial cell DNA repair capacity of carcinoma patients was significantly reduced to 17.1% (15 min) and 23% (30 min) compared to the DNA repair of the control group (36.2%, 15 min and 46.0%, 30 min). Mutagen sensitivity was comparable in patients and controls. Thus, reduced epithelial cell DNA repair capacity of tumor patients is a possible endogenous risk factor for the development of head and neck squamous cell cancer.

Transcriptional repression of DLEC1 associates with the depth of tumor invasion in oral squamous cell carcinoma

The objective of this study was to clarify the expression and epigenetic regulation of DLEC1, a candidate tumor suppressor gene (TSG) located at 3p21.3-p22, in oral squamous cell carcinoma (OSCC) and the clinical relevance of its down-expression. Quantitative RT-PCR was performed to exam the expression level of DLEC1 in matched OSCC and normal oral samples from 57 prospectively enrolled patients (with additional matched leukoplakia samples from 9 patients). We defined DLEC1 down-expression as a 2-fold decrease in expression of DLEC1 between normal tissues and tumors, and determined its correlation with clinical characteristics. Methylation-specific PCR (MSP) and bisulfite sequencing were used to evaluate the promoter methylation status of DLEC1 in 19 OSCC, 19 oral leukoplakia (OL), and 17 normal oral tissues. A statistically significant association between DLEC1 down-expression and invasive depth of OSCC was observed (P=0.026). Besides, expression of DLEC1 decreased sequentially from normal tissues to OL and then to OSCC (P<0.05), which was inversely correlated with methylation status of the DLEC1 promoter. Promoter methylation of DLEC1 increased progressively among normal tissues, OL, and OSCC, as revealed by MSP, and confirmed by sequencing. Treatment of OSCC cell lines with 5-aza-2'-deoxycytidine (5-Aza-dC) reversed the methylation and restored DLEC1 expression. Our results demonstrating that down-expression and promoter methylation of DLEC1 increased from normal tissues to premalignancies and then to malignancies. Furthermore, its transcriptional repression is associated with the depth of tumor invasion.

A review of risk factors and genetic alterations in head and neck carcinogenesis and implications for current and future approaches to treatment

Head and neck cancer is the fifth most common cancer worldwide but the most common malignant disease site in central Asia. The treatment of head and neck cancer is one of the most challenging in clinical oncology because of the high content of hypoxic cells of the cancer which increases resistance to therapy and also because of the high capacity of the cancer to regrow during treatment. For unresectable tumours, radiotherapy and chemotherapy alone or more often in combination is the treatment of choice. The aim of this paper is to review current understanding of carcinogenesis of head and neck cancer in relation to predisposing risk factors in general and for specific sub-sites and how these risk factors interact with the main reported genetic alterations in the progression of the cancer. The implications of these changes in determining choice of therapy are also discussed from a brief historical perspective of the various treatment approaches of head and neck cancer.

Molecular pathogenesis of head and neck cancers

Head and neck cancers represent a progressive genetic malady, with genetic aberrations accumulating in response to carcinogen exposure. Although individual genomic aberrations develop at specific time points in the progression axis, the precise role of these abnormalities in tumor progression and cancer behavior remain to be elucidated. This article will give an overview of the current knowledge on the molecular basis for the development of head and neck cancers.

Evaluation of glutathione S-transferase polymorphisms and mutagen sensitivity as risk factors for the development of second primary tumors in patients previously diagnosed with early-stage head and neck cancer

BACKGROUND

The objective of this study was to evaluate the effects of polymorphisms in 2 genes in the glutathione S-transferase (GST) family and the mutagen-sensitivity phenotype on the risk of second primary tumors (SPTs) in patients with previously diagnosed early-stage head and neck squamous cell carcinoma. Data were available for 303 patients who were enrolled in a placebo-controlled chemoprevention trial of low-dose 13-cis-retinoic acid to reduce the occurrence of SPTs.

METHODS

A Cox proportional hazards model and survival tree analysis were used to evaluate the association between specified genetic variations and the development of SPTs. The average number of bleomycin-induced chromatid breaks per cell was used to quantify mutagen sensitivity as an individual patient's degree of sensitivity to genotoxicity.

RESULTS

The GST-M1 null genotype was associated with an increased risk for any SPTs (hazard ratio [HR], 1.99; 95% confidence interval [95% CI], 1.11-3.56) and for tobacco-related SPTs (HR, 2.16; 95% CI, 1.01-4.62) after adjusting for covariates. The GST-T1 null genotype and bleomycin-induced chromatid breaks were not associated with a statistically significant increased risk for SPTs or tobacco-related SPTs after similar adjustment. Simultaneous nonnull status for both GST genotypes was associated with a decreased risk for any SPTs (HR, 0.52; 95% CI, 0.28-0.96) and tobacco-related SPTs (HR, 0.50; 95% CI, 0.22-1.11) compared with null status for GST-M1 accompanied by nonnull status for GST-T1.

CONCLUSIONS

An association was observed between the development of SPTs and the GST-M1 null genotype after successful treatment for early-stage head and neck squamous cell carcinoma. The GST-T1 null genotype and bleomycin-induced chromatid breaks were not associated with an increased risk, and no significant interactions were identified.

Duration but not Intensity of Alcohol and Tobacco Exposure Predicts p16INK4A Homozygous Deletion in Head and Neck Squamous Cell Carcinoma

In tobacco-associated solid tumors, evidence suggests that the pattern of carcinogen exposure is related to the nature of somatic gene inactivation within crucial pathways, including the retinoblastoma (Rb) pathway. One somatic event in this pathway, homozygous deletion of the p16INK4A gene, is commonly observed in head and neck squamous cell carcinoma (HNSCC). Alcohol and tobacco are both well-established risk factors for HNSCC but there has been little characterization of the relationship of exposure to these carcinogens and inactivation of the p16INK4A gene. Hypothesizing that p16INK4A homozygous deletion is associated with tobacco and alcohol exposure, we investigated 330 consecutive HNSCC tumors. The odds ratio (OR) for p16INK4A homozygous deletion among alcohol consumers in the upper tertile (>43 years used) was 5.2 [95% confidence interval (95% CI), 2.1-12.8] as compared with those with < or = 43 years of alcohol consumption. Intensity of alcohol exposure, measured as average alcoholic drinks per week, was not associated with gene deletion. When we examined the distribution of duration of tobacco use, the OR for p16(INK4A) homozygous deletion was 1.3 (95% CI, 0.5-3.0) and 1.9 (95% CI, 0.9-4.0) for 29 to 39 years and >39 years of tobacco smoking, respectively, as compared with those that smoked < or = 28 years. As in the case of alcohol use, intensity of tobacco exposure (measured as packs per day) was not associated with gene deletion. Hence, the duration of alcohol use and duration of smoking, but not intensity of either, significantly predicted p16(INK4A) homozygous deletion in HNSCC.

The role of human papillomavirus type 16 and the fragile histidine triad gene in the outcome of cervical neoplastic lesions

The presence of high-risk human papillomavirus, loss of heterozygosity on chromosome 3p and fragile histidine triad gene expression were assessed as potential markers of cancer and CIN progression in 83 cervical cancers and 74 cervical intraepithelial neoplasia grade 1 lesions. Human papillomavirus type 16 was an indicator of vascular involvement in cancers. Loss of heterozygosity, especially in the fragile histidine triad gene intron 5, was an indicator of high-grade tumours, greater tumour depth and lymph node involvement. Abnormal fragile histidine triad gene expression was more frequent in cervical intraepithelial neoplasia grade 1 lesions with increased risk of disease progression.

Microsatellite alterations in african americans with head and neck cancer

OBJECTIVE

To determine the genetic differences between African Americans (AA) and Non-African Americans (NAA) with head and neck squamous cell carcinoma (HNSCC).

METHODS

DNA was obtained from tumor tissues and peripheral blood from 18 AA and 19 NAA patients with HNSCC. Microsatellite analysis using a fluorescent technique was performed on chromosomal arms 1p, 3p, 4q, 9p, 13q, and 17p. Statistical analyses were performed on the molecular and clinical outcome data.

RESULTS

Based on the Surveillance, Epidemiologic, and End Result (SEER) data from southeast Michigan, the incidence rate of HNSCC in AA has been higher than for NAA, and the overall 5-year relative survival rate is lower for AA than NAA (36.2% vs. 47.6%). In this study, we found that the rate of loss of heterozygosity of chromosomal arms 1p, 3p, 4q, 9p, 13q, and 17p ranged from 68.8% to 83.3% for HNSCC in AA and from 66.7% to 90.0% in NAA. The difference in the rates of microsatellite alterations in chromosomal arms 3p, 4q, and 9p between AA and NAA were between 12.5% and 20% and were not statistically significant.

CONCLUSION

The incidence and clinical outcomes for AA with HNSCC are different from that of NAA in southeast Michigan. In our group of patients with HNSCC, differences in rates of microsatellite alterations and survival were found between AA and NAA; however, these differences were not statistically significant. We conclude that genetic difference, as determined by the rates of microsatellite alterations, is not predictive of outcome difference between AA and NAA HNSCC patients.

BPDE-induced lymphocytic 3p21.3 aberrations may predict head and neck carcinoma risk

BACKGROUND

Tobacco exposure is an established risk factor for head and neck squamous cell carcinoma (HNSCC). Benzo[alpha]pyrene diol expoxide (BPDE), a main metabolic product of the tobacco smoke constituent benzo[alpha]pyrene, induces chromosomal aberrations at specific loci. Chromosomal aberrations in peripheral blood lymphocytes (PBLs) induced by BPDE may reflect individuals' genetic susceptibility to tobacco carcinogens.

METHODS

This study was designed to detect BPDE-induced aberrations in PBLs at locus 3p21.3 in cultured lymphocytic cells. Our hypothesis is that the presence of BPDE-induced 3p21.3 aberrations is a biomarker of an individual's genetic susceptibility and that individuals with these aberrations are at an increased risk for HNSCC. PBL cultures from 52 cases and 54 controls were treated with 2 microM BPDE for 24 hours before the 3p21.3 aberrations were assessed by fluorescence in situ hybridization. One thousand lymphocyte interphases were scored for each sample.

RESULTS

We found that BPDE-induced chromosome 3p21.3 aberrations occurred more frequently in cases (mean: 31.4 per 1000 cells) than in controls (mean: 22.1 per 1000 cells; P < 0.001). However, when 6q27 was selected as a control locus, no such difference was observed (P = 0.545). When the 75th percentile value of induced aberrations in the controls was used as a cutoff point to classify 3p21.3 BPDE-induced sensitivity, 30 of the 52 cases (57.69%) and only 14 of the 54 controls (25.93%) were sensitive to BPDE exposure. This approach resulted in an odds ratio of 4.8 (95% confidence interval: 1.87-12.28) for HNSCC risk associated with BPDE-induced 3p21.3 aberrations. There was also a dose-response relationship between the number of BPDE-induced aberrations at 3p21.3 and risk for HNSCC.

CONCLUSIONS

The results from this study demonstrated that 3p21.3 may be a specific molecular target of tobacco carcinogens and that BPDE sensitivity at this locus may reflect an individual's genetic susceptibility to HNSCC.

Abnormal FHIT expression profiles in cervical intraepithelial neoplastic (CIN) lesions

Abnormal fragile histidine triad transcripts were found in 20-30% of CIN2/3 lesions and 11% of normal cervical biopsies by RT-PCR. Bi-allelic loss of the fragile histidine triad gene and the loss of fragile histidine triad protein expression detectable by immunochemical staining with a polyclonal fragile histidine triad specific antibody was rare. The genomic changes showed no association with the presence of human papillomavirus types which carry high risk for cervical cancer (high risk human papillomavirus) as assessed by a type-specific multiplex PCR. The presence of abnormal fragile histidine triad transcripts in a subset of CIN2/3 lesions with no high risk human papillomavirus suggests that this could be an independent risk factor associated with an alternative carcinogenic pathway.

DNA content as a prognostic marker in patients with oral leukoplakia

BACKGROUND

Oral leukoplakia may develop into squamous-cell carcinoma, which has a poor prognosis. Risk factors for oral carcinoma have been identified, but there are no reliable predictors of the outcome in individual patients with oral leukoplakia.

METHODS

We identified 150 patients with oral leukoplakia that was classified as epithelial dysplasia and measured the nuclear DNA content (ploidy) of the lesions to determine whether DNA ploidy could be used to predict the clinical outcome. Biopsy specimens obtained at annual follow-up visits were graded histologically and classified with respect to DNA content in a blinded fashion. Disease-free survival was assessed in relation to DNA ploidy and the histologic grade. The mean duration of follow-up was 103 months (range, 4 to 165).

RESULTS

Among 150 patients with verified epithelial dysplasia, a carcinoma developed in 36 (24 percent). Of the 150 patients, 105 (70 percent) had diploid (normal) lesions, 20 (13 percent) had tetraploid (intermediate) lesions, and 25 (17 percent) had aneuploid (abnormal) lesions at the time of the initial diagnosis. A carcinoma developed in 3 of the 105 patients with diploid lesions (3 percent), as compared with 21 of the 25 patients with aneuploid lesions (84 percent), yielding a negative predictive value of 97 percent with respect to the diploid lesions and a positive predictive value of 84 percent with respect to the aneuploid lesions. Carcinoma developed in 12 of 20 patients with tetraploid lesions (60 percent). The mean time from the initial assessment of the DNA content to the development of a carcinoma was 35 months (range, 4 to 57) in the group with aneuploid lesions and 49 months (range, 8 to 78) in the group with tetraploid lesions (P=0.02). The cumulative disease-free survival rate was 97 percent among the group with diploid lesions, 40 percent among the group with tetraploid lesions, and 16 percent among the group with aneuploid lesions (P<0.001).

CONCLUSIONS

The DNA content in cells of oral leukoplakia can be used to predict the risk of oral carcinoma.