Primary screening with liquid-based cytology in an unscreened population in rural China, with an emphasis on reprocessing unsatisfactory samples.

OBJECTIVE: To determine the sensitivity and specificity of liquid-based cytology in a high-risk, unscreened population. STUDY DESIGN: A cross-sectional comparative trial of multiple screening techniques. This report focuses on the performance of liquid-based cytology using biopsy as the standard. RESULTS: In total, 1,997 women were screened. All subjects had a minimum of five cervical biopsies. Of the subjects, 4.3% had CIN 2 on biopsy. The ThinPrep Pap with ASCUS as positive had a sensitivity for CIN 2 of 94% and specificity of 78%; the sensitivity for CIN 3 was 98% and for cancer, 100%. The unsatisfactory rate due to bloody specimens was 7.9% (158/1,997). After reprocessing, the unsatisfactory rate was 0.15% (3/1,997). CONCLUSION: Reprocessing effectively recovers ThinPrep samples otherwise unsatisfactory due to blood and mucus. The ThinPrep Pap test is a highly sensitive screening test when used in a high-risk, unscreened population.

[A methodology study on assessment of cancer screening test].

OBJECTIVE: To analyze the effect of gold standard, blind comparison and different cut-points choosing on screening techniques assessment, and to promote the application of evidence-based medicine theory in screening study. METHODS: A screening study for cervical cancer in rural China in 1999, where 1997 women had been tested for pathology as gold standard and simulating situations without gold standard, blind comparison and under different cut-points. Indices such as detectable rate, sensitivity and specificity were calculated for each technique. Receiver operating characteristics (ROC) curves were drawn and areas under ROC curves between screening techniques were tested. RESULTS: Without gold standard, diagnostic techniques could not be evaluated correctly, and without the blind comparison, the sensitivity and specificity of the tests would be subjectively increased. Furthermore, use of different cut-points led to different sensitivities and specificities of test. CONCLUSIONS: Gold standard, blind comparison and perfect cut-points can improve the quality of screening test and drawing ROC curves is an effective way to confirm cut-points and evaluate diagnostic techniques. It is necessary to enforce the application of evidence-based medicine theory in scientific research.

[Population-based study of human papillomavirus infection in high-risk area for cervical cancer in Shanxi Province, China].

OBJECTIVES: To investigate the prevalence of oncogenic type of human papillomavirus (HPV) infection and identify the high risk population for conducting immuno/chemoprevention of cervical cancer. METHODS: All married women aged 30 to 50 with no history of hysterectomy, pelvic radiation and non-pregnant from certain villages of Xiangyuan and Yangcheng County were invited. This study was conducted through two phases. In phase one, subjects sampled the vaginal secretions using the collectors after signing the informed consent. And physicians sampled exfoliated cells from cervix in the phase two. All the specimens were tested with the Hybrid Capture 2 test. The data was managed and analyzed by VFP and SPSS software. RESULTS: There were 9,683 women participated in this study. Local women welcomed this study and population compliance rate was 75.4%. In tested population, we found 2,666 subjects of HPV DNA positive and HPV prevalence was 27.5%. The rates of different age group were 24.5% (30-34 yrs), 27.4% (35-39 yrs), 28.2% (40-44 yrs), 27.4% (45-50 yrs) respectively and had no significant differences (P = 0.604). The rates were slightly increased with the higher education level and had no differences (P = 0.106). The rate in mountain areas was higher than that in half-mountain areas (P = 0.001). CONCLUSIONS: The prevalence of HPV infection is indeed high in this region. Local women and health professionals welcome the activities of cervical cancer screening and prevention. It is an emergent task to improve their sanitary condition and prevent them from cervical cancer in these women. A women health cohort is established successfully among high HPV exposed women in rural China. The extensive biologic specimen repository has been successfully established to simultaneously study the etiology, early detection, and immuno/chemoprevention of cervical cancer.

Risk factors for HPV infection and cervical cancer among unscreened women in a high-risk rural area of China.

We report a prevalence rate of 23.6% human papillomavirus (HPV) infection with oncogenic subtypes and 2.4% cervical intraepithelial neoplasia (CIN) III and cervical cancer (CC) in rural middle-aged women in 2 counties with the highest CC mortality in Shanxi Province, China. We examined the association of risk factors to HPV infection and to CIN III and CC in 8,798 unscreened women aged 35-50 years. Multivariate odds ratios (OR) and 95% confidence intervals (CI) for each endpoint were obtained for risk factors after adjustment for covariates. The OR of oncogenic HPV were: 1.41 (95% CI = 1.25-1.60) and 1.42 (95% CI = 1.24-1.61) for the participant and her husband having multiple sexual partners, respectively; 1.67 (95% CI = 1.37-2.04), 1.15 (95% CI = 1.04-1.26), and 0.82 (95% CI = 0.72-0.94) for ever (vs. never) diagnosed with tuberculosis, cervical inflammation and vaginal trichomoniasis, respectively; while bathing in a public (v. private) facility had an OR of 1.23 (95% CI =1.11-1.35). Seasonal fluctuations in HPV infection, but not CC, appeared in Xiangyuan County, with OR of 1.23 (95% CI = 1.14-1.33) and 1.51 (95% CI = 1.35-1.67) in Spring and Winter compared to Summer, respectively. The OR of CIN III and CC in the HPV positives were: 2.03 (95% CI = 1.63-2.53) for ages > or =45 years (vs. <40); and 4.01 (95% CI = 1.46-11.0) for > or =3 (vs. no) home births. Public health interventions and control strategies for improving the reproductive health of women in these rural populations need to be developed to reduce risk of HPV and subsequent CC.

[Association between high-risk human papillomavirus DNA load and cervical intraepithelial lesion].

OBJECTIVE: To determine the association between viral load of high risk type human papillomavirus (HR-HPV) and stage of cervical intraepithelial neoplasia (CIN) lesion. METHODS: Cervical exfoliated cells were collected from 1997 women aged 35-45 in a cross-sectional screening study. HPV DNA was detected by hybrid capture 2 (HC2) system, and viral load was measured by the ratios of relative light units compared to standard positive control (RLU/PC). Log10RLU/PC were categorized into four groups: negative (< 0), low viral load (0 - 1.12), medium viral load (1.13 - 2.23), and high viral load (2.24 - 3.37). Cervical lesions were diagnosed by biopsies as normal, CIN 1, CIN 2-3, and squamous cervical cancer (SCC). Association between HR-HPV and CINs were evaluated by unconditional multinomial logistic regression. RESULTS: 100% (12/12) SCC, 97.3% (72/74) of CIN 2-3, 58.3% (74/127) of CIN 1, and 11.5% (205/1784) of normal women were positive for HPV DNA. The median log10RLUs for the positive women with SCC, CIN 2-3, CIN 1 and in normal women were 2.60, 2.32, 2.18 and 1.18 respectively. The odds ratio (OR) between low viral load of HPV DNA and CIN 1 was 3.8 (1.9 - 7.3) while between high viral load and CIN 2-3 was OR=865.9 (200.1 - 3738.0) which showed that higher viral load could increase the risk of cervical lesions (P <0.001). CONCLUSION: Both cervical cancer and CINs were highly influenced by HR-HPV viral load.

[Value of acetic acid smear test for cervical cancer screening].

BACKGROUND & OBJECTIVE: At present, the incidence of cervical cancer is still high in less developed areas of China; one of the reasons is that cytology in screening for cervical cancer is not feasible in these areas. The aim of this study was to analyze the sensitivity and specificity of acetic acid smear test as a cervical cancer screening test, and evaluate the value of this method for cervical cancer screening. METHODS: Acetic acid smear test was performed on 1997 previously unscreened women aged 35-45 years in Xiangyuan County, Shanxi Province. All women had cervical cytology, testing for high-risk types of human papillomavirus DNA, colposcopy, an endocervical curettage and at least five cervical biopsies. Biopsies were done at the lesions, or one biopsy at 2, 4, 8, 10 o'clock at the squamocolumnar junction in each normal quadrant. RESULTS: According to histological diagnosis, 43 women had CIN II, 31 had CIN III, and 12 had invasive carcinoma. In two women only the endocervix was positive. Smear test yielded normal results in 1445 women (72.4%), low-grade squamous intraepithelial lesions (LSILs, CIN I) in 525 (26.3%), high-grade squamous intraepithelial lesions (HSILs, CIN II- III) in 21 (1.1%), and cancer in 6 (0.3%). With abnormal visual inspection defined as LSILs or worse, the sensitivity of acetic acid smear test for HSILs or worse was 70.9% (61 of 86), the specificity was 74.3% (1420 of 1911). The sensitivity was 64.9% for smaller lesions (37 of 57), and 88.9% for larger lesions (24 of 27) (P=0.03). The sensitivity of colposcopy for high-grade SILs or worse was 81.4% (70 of 86), the specificity was 76.5% (1462 of 1911). CONCLUSION: This study showed the high specificity and sensitivity of acetic acid smear test as a primary screening test for cervical cancer. Acetic acid smear test and colposcopy have similar specificity profiles for CIN II or more severe lesions. Acetic acid smear test as a primary screening test will be possible and effective with the benefits of low-cost and simple test in low-resource settings.