Supannee Sriamporn

Prevalence of Opisthorchis viverrini infection and incidence of cholangiocarcinoma in Khon Kaen, Northeast Thailand

Liver cancer is the most common cancer in Khon Kaen, Northeast Thailand, because of the high incidence of cholangiocarcinoma (CHCA). Opisthorchis viverrini (OV), a liver fluke, is endemic in the area, and has been evaluated as a cause of CHCA by International Agency for Research on Cancer. Residents of 20 districts in the province were invited to attend a mobile screening programme between 1990 and 2001. Of 24 723 participants, 18 393 aged 35–69 years were tested for OV infection, by examining stools for the presence of eggs. Prevalence of infection in each district was estimated from the sample of the population who had been tested. The incidence of liver cancer in 1990–2001 was obtained for each district from the cancer registry. The average crude prevalence of OV infection in the sample subjects was 24.5%, ranging from 2.1% to 70.8% in different districts. Truncated age‐standardized incidence of CHCA at ages >35 years varied threefold between districts, from 93.8 to 317.6 per 100 000 person‐years. After adjustment for age group, sex and period of sampling, there was a positive association between prevalence of OV infection and incidence of CHCA at the population level. Associations between CHCA and active OV infection in individuals have become hard to demonstrate, because of effective anti‐OV treatment. The relationship may, however, be clear in comparisons between populations, which, for infectious diseases, take into account the contextual effects of group exposure in determining individual outcome. The cancer registry is an appropriate tool for disease monitoring in small areas.

A Self-Administered Device for Cervical Cancer Screening in Northeast Thailand

OBJECTIVE To test a self-scraping device as a mass screening device against a routine scraping method and to evaluate the acceptance of the self-scraping device by a group of rural females from Northeast Thailand. STUDY DESIGN From a rural area of Northeast Thailand, 552 women were trained and motivated, through primary health care structures, to participate in a cervical cancer screening exercise using a self-scraping device. After one week, the same females were reexamined by gynecologists using the routine scraping method. In both cases the specimens were stained according to Papanicolaou. Through questionnaires the acceptance of the self-scraping device was evaluated. RESULTS Through the self-scraping method, 13 cases suspicious for malignancy were detected. Specimens obtained through examination by physicians confirmed 11 cases to be suspicious for malignancy. No false negative cases were found. In the detection of inflammation, the self-scraping method was not as accurate as examination by a physician. The device was accepted by the females who participated in the study. CONCLUSION In the rural areas of developing countries, where physicians and other trained medical personnel are not often available to carry out regular screening tests on a population basis, the self-scraping method can be applied as an integral part of primary health care for mass screening for uterine cervical cancer.

Cross-reactivity between immune responses to Helicobacter bilis and Helicobacter pylori in a population in Thailand at high risk of developing cholangiocarcinoma

ABSTRACT Helicobacter bilis DNA has been detected in human tissue and is a candidate for etiologic investigations on the causes of hepatic and biliary tract diseases, but reliable serologic tests need to be developed in order to pursue such investigations. The scope of this study was to assess the specificity of two assays for H. bilis immune response allowing for H. pylori, and their cross-reactivity in a population in Thailand at high risk for cholangiocarcinoma. Plasma samples from 92 Thai volunteers were independently tested in two laboratories (Massachusetts Institute of Technology [MIT] and Lund). MIT performed three analyses of H. pylori and H. bilis based either on (i) outer membrane protein (OMP) with no preabsorption or on antigens derived from whole-cell sonicate before (ii) or after (iii) preabsorption with H. pylori sonicate protein. Lund used cell surface proteins from H. pylori and H. bilis as antigens. Testing for H. bilis was preabsorbed with a whole-cell lysate of H. pylori. More than 80% of the samples were positive for H. pylori in both laboratories. As tested by MIT, 58.7% (95% confidence interval, 47.9 to 68.9%) were positive for H. bilis by OMP and 44.5% (34.1 to 55.3%) were positive for H. bilis sonicate protein, but only 15.2% (8.6 to 24.2%) remained positive after preabsorption with H. pylori sonicate protein. Lund found 34.5% of the samples positive for H. bilis (22.0 to 41.0%), which was statistically compatible with all three MIT results. Serologic responses to OMPs of the two bacteria coincided in 66 and 45% of the samples in the MIT and Lund assays, respectively. We found high cross-reactivity between the immune responses to H. pylori and H. bilis antigens. More-specific H. bilis antigens need to be isolated to develop serologic tests suitable for epidemiological studies.

Loss-adjusted survival of cervix cancer in Khon Kaen, Northeast Thailand

For incident cancers of the cervix uteri (601 cases) registered in the population-based cancer registry of Khon Kaen province, Northeast Thailand, in 1985–1990 loss-adjusted survival probabilities were estimated by a logistic regression model with four prognostic factors (age at diagnosis, stage of disease, place of residence and treatment), and compared with observed survival, estimated by the actuarial method. All patients were followed up for a minimum of 5 years, using both passive and active methods. In all, 27.6% of patients were lost to follow-up within 5 years of the index date. The overall observed survival at 5 years was 56.8% and loss-adjusted survival was 54.7%. The difference between the loss-adjusted and observed survival at 5 years was small: 2.1% overall, varying between 0.8 and 3.5 percent units for any prognostic group. The assumption of independence of loss to follow-up and death in the calculation of survival by the actuarial method in this, and probably in other, population-based series, is reasonable and leads to no material bias in the estimates.

The relationship of human papillomavirus (HPV) detection to pap smear classification of cervical-scraped cells in asymptomatic women in northeast Thailand.

Objective: To correlate the detection of human papillomavirus (HPV) with the Pap smear classification of cervical‐scraped cells from asymptomatic women living in northeast Thailand.