Sitakan Natphopsuk

Human Papillomavirus Genotypes and Cervical Cancer in Northeast Thailand

Human papillomavirus (HPV) is a major cause of cervical cancer. More than 100 HPV genotypes have been identified; however the distribution varies geographically and according to ethnicity. The purpose of this study was to investigate the prevalence and distribution of HPV subtypes among Northeast Thai women. Subjects included 198 cases of SCCA and 198 age-matched, healthy controls. HPV-DNA was amplified by PCR using the consensus primers GP5+/6+ system followed by reverse line blot hybridization genotyping. The prevalence of high-risk HPV infection was 21 (10.1%) and 152 (76.8%) in the controls and in the cases, respectively. High-risk HPV significantly increased the risk for cervical cancer with an OR of 42.4 (95%CI: 22.4-81.4, p<0.001) and an adjusted OR of 40.7-fold (95%CI: 21.5-76.8, p <0.001). HPV-16 was the most prevalent HPV type in the SCCA (56.2%) followed by HPV-58 (17.8%) and HPV-18 (13.6%); whereas HPV-58 (46.4%) was a prominent genotype in the controls followed by HPV-16 (39.3%) and unidentified HPV types (25.0%). These findings indicate that HPV infection remains a critical risk factor for SCCA; particularly, HPV-16, HPV-58 and HPV-18. In order to eradicate cervical cancer, sustained health education, promoted use of prophylactics and a HPV-58 vaccine should be introduced in this region.

Risk factors for cervical cancer in northeastern Thailand: detailed analyses of sexual and smoking behavior.

Cervical cancer is a serious public health problem in Thailand. We investigated possible risk factors for cervical cancer including HPV infection, p53 polymorphism, smoking and reproductive history among women in Northeast Thailand using a case control study with 177 cases and age-matched controls. Among the HPV carriers, a significantly increased risk for cervical cancer with an OR of 36.97 (p<0.001) and an adjusted OR of 38.07 (p<0.001) were observed. Early age at first sexual exposure, and multiple sexual partners increased the risk of cervical cancer with ORs ranging between 1.73-2.78 (p<0.05). The interval between menarche and first sexual intercourse<6 years resulted in a significant increase in the risk for cervical cancer with ORs ranging between 3.32-4.09 and the respective adjusted OR range for the 4-5 and 2-3 year-old groups were 4.09 and 2.92. A higher risk was observed among subjects whose partner had smoking habits, whether currently or formerly; with respective ORs of 3.36 (p<0.001) and 2.17 (p<0.05); and respective adjusted ORs of 2.90 (p<0.05) and 3.55 (p<0.05). Other smoking characteristics of the partners including smoking duration≥20 years, number of cigarettes smokes≥20 pack-years and exposure time of the subject to passive smoking≥5 hrs per day were found to be statistically significant risks for cervical cancer with adjusted ORs of 3.75, 4.04 and 11.8, respectively. Our data suggest that the risk of cervical cancer in Thai women is substantially associated with smoking characteristics of the partner(s), the interval between menarche and first sexual intercourse as well as some other aspects of sexual behavior.

Low Prevalence of Toxoplasma gondii Infection Among Women in Northeastern Thailand

Abstract:  Toxoplasma gondii infection was studied in Khon Kaen, northeastern Thailand. Blood specimens were collected from 493 non-pregnant women between 2009 and 2012. Presence of antibodies to T. gondii was determined using the latex agglutination test (cutoff titer 1:32). Thirteen of 493 (2.6%) were found to be seropositive for T. gondii infection. There was no age dependence in the prevalence. The present study reporting a low prevalence of T. gondii infection in northeastern Thailand suggests that the traditional lifestyles and climatic environments may limit the emergence of toxoplasmosis in this region.

Lack of Participation of the GSTM1 Polymorphism in Cervical Cancer Development in Northeast Thailand

The potential association between the GSTM1 deletion polymorphism and risk of cervical cancer was investigated in Northeastern Thailand. DNA was extracted from buffy coat specimens of 198 patients with squamous cell carcinoma of the cervix and 198 age-matched healthy controls. Genotyping of the GSTM1 was conducted by using two PCR methods, a short- and a long-PCR. Distribution of the GSTM1 genotypes in between the cases and the controls was not significantly different (p>0.5 by χ2 test). The results suggest that the GSTM1 deletion polymorphism is not a risk factor for squamous cell carcinoma of the cervix in the northeast Thai women.

Genetic Polymorphism of the Glutathione S-transferase Pi 1 (GSTP1) and Susceptibility to Cervical Cancer in Human Papilloma Virus Infected Northeastern Thai Women

Objective: We aimed to investigate any association between a genetic polymorphism of the detoxification GSTP1 gene and risk of cervical cancer in northeastern Thailand. Materials and Methods: Genotyping of GSTP1 was performed for 198 squamous cell cervical cancer (SCCA) patients and 198 age-matched healthy controls with the PCR-RFLP method. Results: The respective frequencies of the G allele were 0.33 and 0.26 in the controls and cases, the difference being significant (OR = 0.69 [95% CI: 0.50-0.95, p=0.0192]). Among women infected with high-risk types of HPV, being a heterozygous carrier was associated with a reduced risk of cervical cancer (adjusted OR = 0.32 [95% CI: 0.12-0.91, p=0.031]). Similarly, a decreased risk was observed in heterozygous women with a non-smoking partner (adjusted OR = 0.27 [95% CI: 0.09-0.83, p=0.023]). Conclusions: GSTP1 polymorphism could influence susceptibility to cervical cancer among northeast Thai women; either as a independent factor or in combination with high-risk HPV infection. Dual-testing of HPV and the GSTP1 might prove an effective screening tool for cervical cancer.

Haplotype Analysis of MDR1 and Risk for Cervical Cancer in Northeastern Thailand

Objective: The aim of this study was to investigate the association between genotype and haplotype of MDR1 (C1236T, G2677T/A and C3435T) and the risk for cervical cancer in Northeastern Thai women. Methods: An age-matched case-control study involving squamous cell cervical cancer (SCCA) patients (n=204) and healthy controls (n=204) was enrolled for MDR1 genotyping by real-time PCR method. Results: The genotype distribution of MDR1 in both patients and controls was not significantly different (p>0.05). The haplotype analysis showed that T-T-T was the most common haplotype in this population. Significantly increased risk of cervical cancer was observed in carriers of T-T-C and C-G-T haplotypes with ORs of 1.86 (95%CI=1.02-3.39, p=0.0416) and 2.00 (95%CI=1.18-3.40, p=0.0140), respectively. Analysis of 2677-3435 haplotype showed increased risk for cervical cancer in G-T (OR=1.55; 95% CI=1.12-2.13, p=0.0432) and T-C (OR=1.91; 95%CI=1.05-3.47, p=0.0325). Conclusion: The results provide evidence that haplotype of MDR1 may be an important risk factor for cervical cancer development in Northeastern Thai women.

Preliminary Study of the GSTM1 Null Polymorphism and History of Tobacco Smoking among Oral Cancer Patients in Northeastern Thailand.

Risks with GSTM1 genotypes and potential roles of smoking in the susceptibility to oral squamous cell carcinoma (OSCC) were studied in Northeastern Thailand. Study subjects were 79 histologically-confirmed OSCC cases (31 men, 48 women) and 79 age- and sex-matched healthy controls ranging in age from 25 to 84 years. GSTM1 genotyping was achieved by two independent PCR assays. The GSTM1 null allele and the homozygous genotype did not increase risk of OSCC vs the wild type allele and the remaining genotypes. When the focus was on the smoking habit, male subjects who smoked ≥10 or ≥35 years were at significantly increased risk for OSCC with adjusted ORs of 4.88 [95%CI, 1.41-16.87, p=0.012] or 4.94 [95%CI, 1.62-15.12, p=0.005], respectively. A higher risk for OSCC was found for smoking amount; those who smoked >5 or >10 pack-years were at a higher risk with adjusted OR of 4.46 [95%CI; 1.45-13.74, p=0.009] or 3.89 [95%CI; 1.34-11.28, p=0.012], respectively. There are certain smoking patterns that give greater risks and thus both smoking duration and pack-years should be taken into consideration in tobacco related cancer prevention.