Cervical Cancer Screening and Analysis of Potential Risk Factors in 43,567 Women in Zhongshan, China

disease, especially when women who test positive for early markers are immediately linked to sources of diagnostic testing and further healthcare. Because incidence of the disease is inversely associated with the recall rate after screening (Parkin et al., 2005), the success of prevention and treatment programs for cervical cancer depends on contacting and directing women to such sources of proper healthcare (Parkin et al., 2005). Among many important factors, an effective health screening program should include health education, wide coverage of the target population, and a high recall rate for those who test positive. Widespread population screening


Introduction
Cervical cancer is one of the most common gynecological cancers. It is the only gynecological cancer that can be diagnosed early, and early diagnosis increases the chance of cure. Results from many studies have shown that population screening for cervical cancer can disease, especially when women who test positive for early markers are immediately linked to sources of diagnostic testing and further healthcare. Because incidence of the disease is inversely associated with the recall rate after screening (Parkin et al., 2005), the success of prevention and treatment programs for cervical cancer depends on contacting and directing women to such sources of proper healthcare (Parkin et al., 2005). Among many important factors, an effective health screening program should include health education, wide coverage of the target population, and a high recall rate for those who test positive. Widespread population screening 1 programs have just begun in China, and most have not adequately covered target populations.
Since 2011, the city of Zhongshan in Guangdong province, China has conducted a large-scale screening program that uses the liquid-based ThinPrep cytology test (TCT) to screen healthy women 35 to 59 years old for cervical cancer. The program actively promotes collaboration between multiple institutes and encourages integration of regional medical resources. The present study analyzed the effectiveness of the initial phase of this program, focusing on the design and factors that 43567 women.

The national Ethics Review Committee of Zhongshan approved this study
In accordance with the national policy on basic services in public health, the municipal government of Zhongshan developed a program that integrates social resources to conduct government-sponsored cervical cancer screening. The program involves the collaboration of multiple institutes to integrate medical resources across the region. The aim of the program is to screen 150000 women (35-59 years of age; permanent residents) from January 2011 to December 2013. At the end of the program, the population coverage rate will be 50%. As part of the program, the hospitals developed the necessary software to establish a patient database. Basic information for each woman is recorded on a digital personalized ID card, which allows authorized medical personnel to input screening information simultaneously. The participating hospitals established independent management systems to conduct the program using personnel dedicated for the purpose. In addition, the hospitals formed collaborations with the local Women's Federation, Family Planning Commission, and the Community Board to develop outreach mechanisms that promote participant recall and periodically follow-up with high-risk individuals.

Study subjects and methods
In 2011, the Women's Federation, Family Planning Commission, and Neighborhood Committee invited married women from 24 districts of Zhongshan city to participate in a study to evaluate the success of the initial phase of the program. For inclusion in the study a woman had to be married, 35-59 years old, sexually active for at least one year, and a resident of the screening area for at least one year. All participants signed a written consent form prior to undergoing any examination. Women who had undergone hysterectomies due to non-cervical cancer or non-cervical diseases were excluded from the study. Each subject was given a survey before examination that included their age, address, education, occupation, income, sexual history, and history of cervical diseases. A positive TCT test was defined as any positive pathological result, including adenocarcinoma (AC), high-grade squamous intraepithelial lesion (HSIL), low-grade squamous intraepithelial lesion (LSIL); (ASC-US), atypical squamous cells that cannot exclude HSIL (ASC-H), atypical glandular cell (AGC), and squamous cell carcinoma (SCC). Any woman who tested examination and treatment in the hospital. The subjects visits by personnel involved in the screening program. The visit was often conducted by members of the local Women's Federation, Family Planning Commission, or the Community Board. The women whose TCT results showed ASC-US or worse pathological changes were contacted by telephone to receive a follow-up colposcopy, testing for high-risk strains of papillomavirus (HPV), and, if necessary, a cervical biopsy. A false-positive TCT test To collect cervical cells, exfoliated cells were collected using an endocervical brush. The cells were washed into vials containing ThinPrep preservative solution, and processed using the ThinPrep2000 system to make a thin-subjected to Papanicolaou staining, and the slides were screened using the ThinPrep imaging system. Images were interpreted by pathologists who made a cytological diagnosis, and these were recorded in signed reports. The Bethesda System recommended by the International Cancer Society (Ma, 2008) was used for cervical cytology diagnoses, especially an ASC-US diagnosis. Images that met any of the following characteristics were diagnosed as ASC-US: empty cells with either a large nucleus or double nuclei, which did not meet the criteria for a diagnosis of LISL; enlarged nuclei 1.5-2.5 times larger than normal that contained high density and irregular chromatin distribution; atrophy of the epithelial layer; atypical hyperplasia, nuclear density (slightly stained nuclei, slightly increased nuclear-tocytoplasm ratio, clear nuclear contour), and increased chromatin; or non-typical squamous epithelial cells or nuclear polymorphism.
contact. The local Women's Federation, who received information regarding subjects who failed to respond to was monitored by 24 district hospitals. Women with a positive TCT test who received further treatment within 6 months were considered successfully recalled.

Statistical analyses
SPSS13.0 software was used for statistical analyses. Data are presented as the frequency and percentage in non-quantitative data analyses. The mean and standard deviation (for normally distributed data) or median and quartile (for non-normally distributed data) were used in quantitative data analyses. For the analysis of factors 2 ) test was in the single factor analyses were integrated for multifactor logistic regression (forward logistic regression, inclusion statistical level = 0.05, and exclusion level = 0.1). In the multivariate regression model >55 years of age was selected as the reference group, as age is a categorical value.

Results
Demographic information of the screening population subjects for the study of the initial phase of the screening program from March 2011 to December 2011. However, 1369 women were excluded because of age (<35 years) or incomplete information. Therefore, 43567 women were screened as part of the study (Table 1). The average age of the participants was 45.52 ± 6.62 years. Of the 43567 subjects, 9392 had a history of cervical diseases (21.6%) and 596 had a family history of cervical cancer (1.4%). The average number of times the subjects had given birth had sexual intercourse was 23.98 ± 3.44 years. Condoms were used by 5360 (   colposcopic examination and biopsy.

Analysis of factors associated with cervical cancer
In single factor analyses, subjects' age, location of residence, education, occupation, income, history of of sexual intercourse during menstruation were associated with positive TCT results ( Table 2). The TCT positive rate was higher in women: younger than 50 years of age, urban residents, self-employed, company white-collar workers, working in service sectors, low-income, with a history of cervical diseases, who became sexually active before 20 years of age, and with a history of intercourse during menstruation (P < 0.05). However, there was no association between positive TCT results and family history, average number of births, or condom use (Table  2).
After multi-factor analysis, age, location of residence, income, and age at which women became sexually active were still significantly associated with TCT results, suggesting that these factors are independent factors that over 50 years of age, the risk of a positive TCT result and 45-49 years (P < 0.001, P < 0.001, and P = 0.006, intervals (CIs) of these age groups were OR 1.541 (95% CI 1.223-1.942), OR 1.532 (95% CI 1.234-1.901), and OR 1.356 (95% CI 1.092-1.683), respectively. The probability of a positive TCT result was higher in rural than urban residents (OR 1.489, 95% CI 1.273-1.742; P < 0.001) and in women with a monthly income of $205.15 (USD) or less (OR 1.218, 95% CI 1.061-1.401; P = 0.005). Compared to women who were >24 years of age when they became sexually active, women who were <20 and women who positive TCT test (OR 1.306, 95% CI 1.015-1.682, P = 0.038; and OR 1.165, 95% CI 1.034-1.312, P = 0.012, respectively).
In single factor analyses the recall rate was associated intercourse, and history of intercourse during menstruation ( Table 3). The recall rate was lower in subjects older than 50 years of age, women residing in urban areas, women with poor education, and women who became sexually active at a young age (<24 y). The recall rate was higher in women with a history of intercourse during menstruation (P < 0.05). Occupation, income, history of cervical diseases, family history of cervical cancer, average number of births, and use of condoms were not related to the rate of positive TCT (P > 0.05).
It was found after multi-factor analyses that age, location that these factors were independently contributing to the recall rate. Compared with women over 55 years of age, the probability of recall was higher in women 35 years or younger (OR 1.912, 95% CI 1.224-2.989, P = 0.004), which was similar to other groups (P > 0.05). The probability of successful recall was higher in urban residents (OR 1.579, 95% CI 1.140-2.185, P = 0.006). The probability of successful recall was also higher in women (OR 1.905, 95% CI 1.143-3.176, P = 0.013) but was not years (P > 0.05). The probability of recall was higher in women who had intercourse during menstruation (OR 3.561, 95% CI 1.037-12.230, P = 0.044).

recalled cases
The results of the single factor analyses indicated that age, location of residence, and being HPV-positive were associated with a positive pathological examination ( Table 4). The probability of positive pathologic results were higher in women <50 years of age, urban residents, and women positive for HPV (P < 0.05).  The multi-factor analyses showed that a subject's age with the probability of a positive pathologic examination, suggesting that these parameters are independent risk risk of a positive pathology result was similar in subjects aged 50-54 y (P younger subjects aged <35 (OR 1.912, 95% CI 1.148-4.108, P = 0.017), 35-40 (OR 1.399, 95% CI 1.014-3.584, P = 0.045), and >45 years (OR 1.102, 95% CI 1.018-3.667, P = 0.044). In general, subjects under 50 years of age had a higher probability of a positive pathology examination (OR: 1.907-2.172) than older women, and a positive HPV test predicted a higher probability of positive pathology results (OR 22.872, 95% CI 9.931-52.678, P < 0.001). The false-positive rate for TCT screening is shown in Table 5.

Discussion
Cervical cancer has a higher incidence than any other cancer worldwide and is one of the greatest threats to women's health. Appropriate screening programs, early diagnosis, and early treatment are key to cervical cancer prevention and treatment (Wang et al., 2013). Building from the established cervical cancer screening program in Zhongshan, the Cervical Cancer Screening Task Force initiated the "Large-Scale Cervical Cancer Screening and Intervention Model in Adult Women in Zhongshan" project. The program is fully supported and sponsored by the municipal government of Zhongshan city. The initial phase of the program, screening 43567 women the rate of successful recalls was 63.36%, and the rate of 30.51% (267/875). These data are valuable information regarding the acceptance of the screening test by the women of Zhongshan and the prevalence of the disease in Zhongshan. Through the early stages, the program has established a basis for developing a more effective model for future screening.
The initiation and pathogenesis of cervical cancer is a complex biological process. However, it is possible by screening to achieve early diagnosis, treatment, prevention, and control of the disease. The TCT has proven to be an effective method of screening for cervical cancer and precancerous lesions in numerous studies. The current work has shown that in single-factor analyses, a woman's age, place of residence, education level, occupation, income, history of cervical diseases, positive TCT result. In more stringent logistic regression analyses, the prominent risk factors related to a positive TCT result were 1) age, particularly 35-49 y, which is consistent with previous reports (Lu, 2007;Sun, 2010;Wei, 2012); 2) rural residence, possibly attributable to poor hygiene, multiple pregnancies, and lack of formal screening, consistent with work by Wang (2004); 3) multiple births, which could cause mechanical injuries to the cervix, squamous metaplasia of the transitional area, and increase in vulnerability to carcinogenic factors during the process of tissue repair; and 4) becoming sexually active at a young age (<20, which is likely due to pubertyassociated cervix squamous metaplasia, repeated exposure to infections, injuries, and cell changes induced by sperm, consistent with work showing intercourse before 15 years of age is associated with higher risk (5-10 fold increase) of cervical cancer (Junej, 2003). These factors, alone or in of cancer after a latency period.
The effectiveness of cervical cancer prevention and treatment programs is directly related to the successful recall of women who receive further testing and healthcare from China of the factors that affect the recall rate of women who test positive during screening. Results of the and positive HPV infection status. A higher rate of positive TCT test results was found in women aged 35-49 years (33.1%, 237/712), and a lower rate (18.83%, 30/159) was observed in women 50 years of age and older. These results suggest that pathologic changes may occur in the cervix of younger women. This may be due to the higher rates of HPV infection in younger women. In the current study, 42.8% of women who tested positive for HPV also had positive pathology test results.
Lack of knowledge about cervical cancer and precancer screening are major reasons for low rates of participation and recall (Besler, 2007). A woman's age, institutes should consider including women 35 years and younger in cervical cancer screening, improve education about cervical cancer screening in target populations to promote a high response rate, and improve accessibility to screening centers for those who live in remote areas. Furthermore, improvements are necessary in medical service coverage and accessibility of care for women management for women once they are in care. These factors are crucial to the core social mission of large-scale screening programs in healthy populations and are key to the effective prevention and treatment of cervical cancer. In ongoing work, the cervical cancer task force is planning to initiate outreach programs to promote followup visits for patients recruited in the rest of the program.
computer software with access to the database of screened women will remind hospital personnel to contact patients by telephone. The task force will collaborate with the local women's federation, family planning commission, and the local community board to establish a dedicated database of screening records to ensure that high-risk perform follow-ups.
In conclusion, the goal of cervical cancer screening is the early detection of precancerous lesions and related abnormalities. The program described in this study is a unique, city-wide, free screening program that is trying to establish a community-medical services network for managing high-risk women and connecting them to care. Our aim is to develop the best model for large-scale screening in otherwise healthy populations in China. This program is being conducted under the guidance of the government, and will be accomplished through close collaborations among different institutes and organizations which allowed the integration of regional medical resources. The experience gained here in Zhongshan can serve as a solid basis for a nation-wide cervical cancerscreening program.