Comparative study between Pap smear and visual inspection using acetic acid as a method of cervical cancer screening

This prospective study was done for the comparison of visual inspection using acetic acid (VIA) and Pap smear as a method of cervical cancer screening. This study was also done to determine the proportion of women screened positive with VIA and proportion of women screened positive with Pap smear. Another aim was to compare the sensitivity and specificity of VIA and Pap smear. A total of 300 women attended to the outpatient gynecologic clinic and cervical cancer screening programme at Bangabandhu Sheikh Mujib Medical University (BSMMU) were included. On VIA, 23 out of 300 women screened had aceto-white lesions. On Pap smear, 14 out of the 300 women had ASCUS or worse lesions. Of the 300 enrolled women, 11 were positive on both VIA and cytology; 12 were positive on VIA only; and 3 were positive on cytology only. Those women (n=26) who showed positive test result with either VIA or Pap smear or both tests were further subjected to colposcopy directed biopsy. Histology was taken as gold standard to compare the performance of VIA and cytology (Pap's smear). Histological diagnosis of CIN/cancer was made in 18 Positive cases out of the total 26 patients who underwent biopsy. Pap smear picked up 10 out of the 18 biopsy-proven cases whereas VIA could identify 17 out of the 18 CIN/carcinoma cervices. VIA was more sensitive (94.44%) than pap smear (55.55%), which was statistically significant. However, the specificity of VIA was slightly lower (97.87%) than that of cytology (98.58%). The PPV of VIA was 73.91% versus 71.42 % for Pap smear.     

Role of VIA in cervical cancer screening in low-resource countries

Cervical cancer is one of the few highly preventable cancers. The early detection and removal of precancerous cervical lesions effectively abolish the development of invasive cervical cancer. The Pap test has been the standard screening test in the Western world for the last five decades. Visual inspection of cervix with acetic acid (VIA) is currently more popular method of cervical cancer of screening test in low resource countries. Cervical cancer incidence and mortality have been reduced dramatically as a result of successful screening in many countries. Cancer cervix can be prevented through both primary prevention using human papilloma virus (HPV) vaccine and early detection using screening techniques. Several screening modalities are now available for early detection of cervical cancer and its precursor lesions. They all differ with regard to their test characteristics, feasibility and economic considerations. This review has different aspects of these screening modalities and provides different options considering mass application. In developed countries, Pap smear cytology is used for cervical cancer screening. But in low-resource country, like Bangladesh, it is too expensive and is not feasible. VIA, a non-cytological test is a simple and inexpensive test which can be provided by trained paramedical personnel with a short training. So VIA can be done in low-resource countries for screening of cervical cancer as an alternative to Pap smear cytology.     

Identifying women with cervical neoplasia: using human papillomavirus DNA testing for equivocal Papanicolaou results

CONTEXT: A Papanicolaou (Pap) test result of atypical squamous cells of undetermined significance (ASCUS) presents a clinical challenge. Only 5% to 10% of women with ASCUS harbor serious cervical disease, but more than one third of the high-grade squamous intraepithelial lesions (HSILs) in screening populations are identified from ASCUS Pap test results. OBJECTIVE: To determine whether human papillomavirus (HPV) DNA testing of residual material from liquid-based Pap tests and referral of cases found to be HPV-positive directly to colposcopy could provide sensitive detection of underlying HSILs in women with ASCUS Pap results, compared with repeat Pap testing. DESIGN AND SETTING: Natural history of women with ASCUS Pap smear results, all of whom had liquid-based cytology, HPV testing, and subsequent repeat Pap tests and colposcopy with histologic evaluation, conducted at 12 gynecology clinics in a large managed care organization between October 1995 and June 1996. PARTICIPANTS: From a cohort of 46009 women who had routine cervical examinations, 995 women with Pap test results of ASCUS who consented to participate were identified. MAIN OUTCOME MEASURES: Cervical histology, HPV test results, and repeat Pap smear results, and sensitivity of HPV testing to identify patients found to have HSIL+ histology. RESULTS: Of 995 participants with ASCUS Pap test results, 973 had both a definitive histologic diagnosis and HPV result. Sixty-five (6.7%) had histologic HSIL or cancer. For women with histologic HSIL+, the HPV test was positive in 89.2% (95% confidence interval [CI], 78.4%-95.2%), and the specificity was 64.1 % (95% CI, 60.9%-67.2%). The repeat Pap smear result was abnormal in 76.2% (95% CI, 63.5%-85.7%). Triage based on HPV testing only or on repeat Pap testing only would refer similar proportions (approximately 39%) to colposcopy. The sensitivity of HPV DNA testing for HSIL was equivalent to, if not greater than, that of the repeat Pap test. We further estimated that an HPV-based algorithm including the immediate colposcopy of HPV-positive women, and then repeat Pap testing of all others, would provide an overall sensitivity of 96.9% (95% CI, 88.3%-99.5%). CONCLUSIONS: For women with ASCUS Pap tests, HPV DNA testing of residual specimens collected for routine cervical cytology can help identify those who have underlying HSIL. By testing the specimen collected at initial screening, the majority of high-risk cases can be identified and referred for colposcopy based on a single screening.     

Molecular testing of human papillomavirus in cervical specimens

OBJECTIVE: To improve the diagnosis of cervical neoplasia by early detection of human papillomavirus (HPV) in uterine cervix, by adding molecular testing of HPV using hybrid capture 2 (HC2) and polymerase chain reaction (PCR) tests to Papanicolaou (Pap) test. METHODS: One hundred women were enrolled in this study. The mean age (mean +/- SD) was 41.97 +/- 8.76 years and the range was 27-65 years. All women had undergone cervical cytological screening with cervical cytology, HPV DNA testing by HC2 and PCR, during the period from January - December 2006, at King Abdul-Aziz University Hospital (KAAUH) and King Fahd Research Centre, Jeddah, Saudi Arabia. RESULTS: The results we obtained by HC2 for detection of HPV were 5 (5%) high-risk HPV, one low-risk HPV (1%) and 94 (94%) negative cases. The PCR detected only 4 (4%) cases. Using the HC2 test as a reference, the sensitivity, specificity, positive predictive, negative predictive values and accuracy of baseline Pap were 50, 85, 17.7, 96.4, and 83%; of final Pap smear were 100, 96.8, 66.7, 100, 97%, and for PCR were 66.7, 100, 100, 97.9, and 98%. The Pap test was repeated within a year for patients with abnormal Pap or negative Pap test with positive HPV DNA. CONCLUSION: Combined screening by cytology and HPV testing using both HC2 and PCR sensitively detects women with existing disease. The absence of HPV DNA provides reassurance that patients are unlikely to develop cancer for several years. We suggest using Pap with HC2 and PCR in screening programs to ensure that women with the double negative result at baseline might safely be screened at longer intervals.     

Awareness and Practice of Cervical Cancer Screening among Female Health Professionals in Murtala Mohammed Specialist Hospital, Kano

Background: Cervical cancer, although largely preventable, remains the most common cause of cancer mortality among women in the developing world. Other members of the community see health care workers as models, therefore their attitudes and actions are predictors of societal health behaviour. Objectives: We assessed the knowledge, attitude and practice regarding prevention of cervical cancer among female health professionals in a secondary health facility in Kano, Nigeria. Methods: A structured questionnaire was administered on 230 female respondents in the various health professions including doctors, pharmacists, nurses and laboratory technologists in Murtala Mohammed Specialist hospital, Kano. Results: Over 60% of the respondents were able to correctly identify all the important aetiological factors associated with cervical cancer, while a similar figure knew the important signs and symptoms of the disease. Up to 94.7% of the respondents had a positive attitude towards Pap smear while 8.2% disapproved of it. Only 20.8% of the respondents have had a Pap smear done previously. Married respondents were more than four times likely to have had a previous Pap smear compared to their single counterparts. (X(2) = 13.3 df=1 P = 0.0003)[O.R=4.8, 95% confidence interval= 1.9 -14.4]. In contrast, religion appeared to have no significant influence on the practice (X(2)= 0.87 df=1 P=0.35). Conclusions: Despite a moderately high level of knowledge of cervical cancer screening and positive attitude towards it, the uptake of Pap smear was low. There is a need for continuing education to improve uptake of these services by health professionals so as to serve as a motivating factor for the public. Key words: cervical cancer screening, pap smear, female health workers, knowledge, practices.     

The positive experience of screening quality among users of a cervical cancer detection center

BACKGROUND: Our objective was to determine the main factors associated with increased utilization of a cervical cancer screening program (CCSP) in a population with a high mortality rate due to cervical cancer. METHODS: A population-based study was carried out in the Mexican state of Morelos, Mexico. The study population included 3,197 women between the ages of 15 and 49 years who were selected at random using a State Household Sampling Framework in the State of Morelos's 33 municipalities. The sample included 2,094 women with a history of a previous Papanicolaou (Pap) test. RESULTS: A previous experience of good screening quality is strongly associated with greater use of the CCSP (OR = 4.2; 95% confidence interval [CI], 1.6-10.9). The educational level of the head of the family is related to more frequent use of Pap smear services. Women whose husbands have 13 or more years of education (OR = 1.8; 95% CI 1.1-2.9) were more likely to have been screened. Similarly, women who had used two or more family planning methods (OR = 1.6; 95% CI 1.2-2.1) and those who knew why the Pap test was given (OR = 3.0; 95% CI 2.1-4.3) had a better history of Pap screening. CONCLUSIONS: In areas where coverage of cervical cancer screening is low, a CCSP that guarantees the quality of all the different elements of care is essential if obstacles to cervical cancer prevention are to be eliminated. It is of particular importance to take into account and satisfy the perceptions and expectations of the women at risk.     

A clinical review of cervicography

A new investigative modality, cervicography, has been advocated for cervical screening. In the first 51 patients referred for colposcopy because of an abnormal cervicogram, none had invasive cancer and 75% had preinvasive cancer. The cervicogram appears superior to cytology but inferior to colposcopy in the detection of cervical pathology. Based on the available evidence, however, cervicography cannot be recommended for universal screening. It may have a role in the follow-up of patients with a mildly abnormal cervical smear, but the optimum management remains early referral for colposcopy.     

绝经后妇女宫颈癌临床分析

目的了解绝经后宫颈癌临床病理特点，探讨绝经后宫颈癌筛查的必要性。方法对24例绝经后宫颈癌临床资料进行回顾性分析，并以同期生育年龄宫颈癌56例作为对照。结果绝经组与未绝经组比较，绝经组阴道接触性出血较未绝经组发生率低（P〈0．01），两组临床分期、淋巴结转移率、宫颈涂片及细胞学检查阳性率差异无统计学意义（P〉0．05），绝经组宫颈腺癌发生率占4．2％，未绝经组占28．8％，两组中腺癌发生率差异有统计学意义（P〈0．01）结论绝经后妇女宫颈癌发病期别通常较晚，绝经后宫颈病变筛查是必要的，定期妇科检查、宫颈涂片细胞学检查可帮助绝经后妇女预防宫颈癌。     

绝经后妇女宫颈癌临床分析

目的了解绝经后宫颈癌临床病理特点,探讨绝经后宫颈癌筛查的必要性。方法对96例宫颈癌临床资料进行回顾性分析,并以同期生育年龄宫颈癌226例作为对照。结果绝经组与未绝经组比较,绝经组阴道接触性出血较未绝经组发生率低(P<0.01),两组临床分期、淋巴结转移率、宫颈涂片细胞学检查阳性率及HPV检测阳性率无显著差异(P<0.05),绝经组宫颈腺癌发生率占5.2%,未绝经组占28.8%(65/226),两组中腺癌率发生率差异显著(P<0.01)。结论绝经后妇女宫颈癌发病期别通常较晚,绝经后宫颈病变筛查是必要的,定期妇科检查、宫颈涂片细胞学检查及高危型HPV检测可帮助绝经后妇女预防宫颈癌。     

Correlation of cervical cytology with cervical histology

OBJECTIVE: To correlate cervical cytology with Cervical histology. METHODOLOGY: A hospital based prospective study was carried out in consecutive total forty-three patient attending oncology clinic of Kathmandu Medical College Teaching Hospital, Sinamangal, Nepal from 1st Bhadra 2061 to end of Falgun 2061 (18th August 2004-12th February 2005) during authors posting in this clinic. All patients who underwent cervical biopsy on either indication of clinically suspected lesions or abnormal cytology were correlated with Pap smear report. Pap smear was carried out in conventional technique using Ayre's spatula. Cervical biopsy was carried out with help of punch biopsy forceps in operation Theatre without the guidance of colposcopy. All pertinent information regarding patient profile in terms of their age, parity, age at marriage, age at 1st child birth, smoking habit, contraceptive use, and symptom of vaginal discharge was taken. Reports of Pap smear and cervical biopsy of these patients were collected from oncology clinic during their follow up visit and all these information and finding were entered in structured questionnaire. The reporting of Pap smear was done in Bethesda system. The average duration between performing Pap smear and biopsy was of one month. Statistical analysis was carried out by EPI-INFOS6 system. RESULT: Of forty three patients who underwent cervical cytology 22 cases were of Benign lesion, 8 cases of LSIL, 9 cases of HSIL, 3 cases of invasive carcinoma and 1 of ASCUS. Sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy and p-value in benign grade was 76%, 83.3%, 86.4%, 71.4%, 79.1%, 0.0004 respectively. Similarly sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy and p-value in LSIL was 60%, 93.9%, 75%, 88.6%, 86%,0 .0008 respectively. For HSIL it was 100%, 89.5%, 55.6%, 100%, 90.7 0.0001 respectively. Respectively for carcinoma it was 100% for sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy p-value was 0.00008. CONCLUSION: Pap smear significantly correlated with cervical histology.     

液基细胞学检查与宫颈巴氏涂片的比较

目的 :探讨 Thinprep液基细胞学检查用于宫颈癌筛查与宫颈巴氏涂片相比的优越性。方法 :将门诊以宫颈疾病就诊的病人随机分为观察组和对照组 ,观察组 2 5 72例 ,用Thinprep液基细胞学检查初筛 ,对照组 1 2 0 8例 ,用宫颈巴氏涂片初筛。结果 :Thinprep液基细胞学的 L SIL以上病变检出率比宫颈巴氏涂片增加了 81 .5 7% ,L SIL、 HSIL的检出率分别增加了 75 .1 3%、1 1 0 .86%。液基细胞学、宫颈巴氏涂片与病理学检查诊断符合率分别为 84.69%、61 .33%。结论 :液基细胞学检查是细胞学领域的重大进步 ,大大提高了细胞学诊断的准确性     

宫颈涂片和宫颈照像技术对宫颈癌筛查的比较

目的:评价宫颈照像技术在宫颈癌筛查中的作用.方法:对194例宫颈病变专科门诊的患者,前瞻盲法,专人分组同时进行宫颈涂片、宫颈照像、阴道镜下取活检.宫颈涂片应用Autocyte液基薄层法,TBS分类报告;宫颈照像仪(Mediscope KCSG-1)的报告按1995年NTL修订分类;以组织病理学为金标准,比较两种筛查方法.结果:阳性预测值、阴性预测值、漏诊率、误诊率、特异度、灵敏度,统计学显示两组间P值均＜0.01.宫颈照像在生育年龄妇女的特异性高(99.30%),阳性预测值高(95.65%),但漏诊率相对高(56.86%).宫颈涂片漏诊率明显偏低(11.76%),灵敏度高(88.24%),但特异性(75.52%)低于宫颈照像(99.30%),误诊率增高(22.48%).结论:在宫颈癌筛查中细胞病理学占主导地位,宫颈照像可以作辅助手段.     

液基细胞学在宫颈疾病诊断中应用

目的探讨液基细胞学（TCT）检查在诊断宫颈疾病中临床价值。方法收集我院2011年8月“2012年8月门诊和住院妇产科患者1150例,进行宫颈TCT检测,1200例进行宫颈阴道细胞学巴氏涂片染色,两种方法检查结果阳性行宫颈电子阴道镜检查及多点活检。结果TCT制片和传统巴氏涂片法对低度鳞状上皮内病变（LSIL）以上病变的检出率分别为4．28％、1．78％,P〈0．01。TCT检出LSIL、高度鳞状上皮内病变（HSIL）、鳞状细胞癌（SCC）与阴道镜活检阳性符合率分别为83．33％、88．23％、100％高于巴氏涂片法的60％、66．66％、100％,P〈0．05。结论对LSIL和HSIL的患者,宫颈TCT检查可作为宫颈疾病普查的首选方法之一。     

子宫颈癌早期筛查方法的研究进展

子宫颈癌是女性常见恶性肿瘤之一,严重危害着广大妇女的健康与生命。进行早期筛查,对子宫颈癌的防治有着重要的意义。传统筛查方法巴氏涂片、肉眼观察,以及如今发展的液基细胞学、人类乳头瘤病毒检测、阴道镜检查等都属于无创检查。有创检查包括子宫颈活检、锥切等病理检查。在此就子宫颈癌早期筛查方法研究进展予以综述。     

五种检测方法在宫颈癌及其前期病变筛查中的准确性评估

目的 比较5种现行的筛查方法在宫颈癌高发地区的应用,从而评价出最佳宫颈癌筛查方案,进而在浙江省范围内推广.方法 在浙江省丽水市某社区内计划选取1005名年龄在25～65岁、有性生活的女性进行宫颈癌筛查,筛查手段选择巴氏涂片、液基细胞学、HPV-DNA检测法、肉眼观察辅以醋酸白染色(VIA)和肉眼观察辅以Lugol's碘染色(VILI)5种.所有筛查者均接受阴道镜检查,以病理组织学结果为金标准,阴道镜检查无异常作为阴性结果.结果 巴氏涂片对宫颈上皮内高度病变的敏感度、特异度、阳性预测值、阴性预测值分别如下:25%,90%,26.7%,98.6%;液基细胞学的上述指标分别为81.3%,97.3%,35.1%,99.6%;VIA上述指标为:68.9%,82.8%,7.1%,99.3%;VILI上述指标分别为:81.3%,84.6%,9.1%,99.6%;HPV-DNA检测法上述指标为:87.5%,77.3%,6.8%,99.7%.结论 液基细胞学的诊断价值好于其余4种方法,可作为宫颈癌筛查的首选方法;肉眼观察由于其简单易行,价格低廉,可适用于经济欠发达地区的普通人群的筛查.

Abstract：

Objective To evaluate five screening methods of cervical cancer so as to popularize an effective screening strategy for cervical cancer in Zhejiang province. Methods A total of 1005 women aged 25 -65 years old were selected from Lishui where cervical cancer was highly prevalent. And 859 subjects were ultimately enrolled between June 2009 and December 2009. Each subject was subjected to five screening methods, including Pap smear, liquid-based cytology (LBC), human papillomavirus DNA with a second-generation hybridization assay( HC2 ), visual inspection with acetic acid (VIA) and visual inspection with Lugol's iodine (VILI). CIN (cervical intraepithelial neoplasia) 2 + on biopsy was used as the reference standard for disease positivity. Negative colposcopy was accepted as a negative outcome. Results The sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV)were 25%, 90%, 26.7% and 98.6% for Pap smear; 81.3%, 97.3%, 35. 1% and 99.6% for LBC;68.9%, 82. 8%, 7. 1% and 99. 3% for VIA; 81.3%, 84. 6%, 9. 1% and 99.3% for VILI; 87. 5%,77.3% and 6. 8% for HPV-DNA test respectively. Conclusions LBC is associated with a better profile of sensitivity, specificity and predictive value for five screening methods. It has the potential of optimizing the effectiveness of primary cervical cancer screening. Due to a low cost and an easy operation, VIA screening is an effective method of screening cervical cancer in the underdeveloped areas.     

宫颈癌及其癌前病变筛查方法现状

本文评价了目前新发展和常用的几种筛查宫颈癌及其癌前病变的方法。按照国家和地区的资源条件和人群风险度不同,肉眼观察,阴道镜检,HPVDNA检测,薄层液基细胞学和自动阅片系统单独或联合使用。均是很有价值的筛查手段。新发展的技术有利于在资源较差的贫困地区扩大宫颈癌普查的范围,通过对高风险人群的重点防治,可获得更好的成本-效益性。     

Correlation of PAP smear findings with clinical findings and cervical biopsy

Objectives: Carcinoma of the cervix is the most common cause of the death in Nepal. Cervical carcinoma does not develop suddenly from normal epithelium but is presented by a spectrum of intraepithelial neoplastic changes that are precancerous lesion and were termed as cervical intraepithelial neoplasia (CIN). Cervical cytological screening is designed to detect over 90% of cytological abnormalities. It has also been established that most cervical cancers can be diagnosed at the preinvasive stage with adequate and repetitive cytological screening. Keeping in view of the importance of carcinoma and the precancerous lesion (CIN) of cervix, study of different methods for the early detection of abnormalities in cervix, correlation with the clinical findings and comparison between the techniques was carried out. Material and methods: Patients with suspicious cervix attending Gynaecology OPD of TUTH and Western regional hospital (Pokhara) who have undergone for pap smear cytology test along with biopsy were selected. Detail history with clinical examination was performed and the findings were correlated. Results and conclusion: Unhealthy cervix with discharge was found to be common even in chronic cervicitis however bleeding and tenderness were associated with more advanced lesions. Pap smear test was found to be equally sensitive to histopathological examination for the early detection of different cervical lesions. However, it is advised to perform biopsy if any abnormalities are detected in pap smear for correlation and confirmation. Key words: Pap smear, CIN.     

宫颈刮片脱落细胞学检查在宫颈癌普查中的作用

目的:探讨宫颈刮片脱落细胞学检查在宫颈癌筛查中的作用。方法:回顾性分析行宫颈刮片脱落细胞学检查的5 801例妇女临床资料,分析宫颈刮片脱落细胞学检查结果异常受检者的病理学诊断结果以及各年龄段受检者宫颈病变的情况。结果:5 801例中,2 799例未见核异质细胞,2 914例有轻度核异质细胞,88例有轻度不典型增生细胞。其中45~55岁年龄段受检者检查异常率最高,为1.79%（61/3 413）。80例为轻度不典型增生细胞,5例为重度不典型增生细胞,3例发现癌细胞。88例宫颈刮片脱落细胞学检查异常的受检者中,发生宫颈上皮内瘤变的有13例。结论:宫颈刮片脱落细胞学检查是宫颈癌普查的首选方法,可早期发现宫颈癌癌前病变,有利于早期实施干预,降低宫颈癌的患病率。     

绝经后妇女宫颈癌96例临床分析

目的:了解绝经后宫颈癌临床病理特点,探讨绝经后宫颈癌筛查的必要性。方法:对96例绝经后宫颈癌临床资料进行回顾性分析,并以同期生育年龄宫颈癌226例作为对照。结果:绝经组与未绝经组比较,绝经组阴道接触性出血较未绝经组发生率低(P<0.01),两组临床分期、淋巴结转移率、宫颈涂片细胞学检查阳性率及HPV检测阳性率无显著差异(P>0.05),绝经组宫颈腺癌发生率占5.2%,未绝经组占28.8%(65/226),两组中腺癌发生率差异显著(P<0.01)。结论:绝经后妇女宫颈癌发病期别通常较晚,绝经后宫颈病变筛查是必要的,定期妇科检查、宫颈涂片细胞学检查及高危型HPV检测可帮助绝经后妇女预防宫颈癌。     

宫颈疾病筛查项目在妇科专项体检中的应用状况

 目的 调查宫颈疾病筛查项目在常规体检中的应用状况。方法 回顾分析2010年1月1日至2011年12月31日复旦大学附属妇产科医院体检中心所有参加体检的24 135例次资料,调查其宫颈疾病筛查项目状况,包括巴氏涂片检查(Papanicolaou smear,Pap)、液基细胞学检测(thinprep cytology test,TCT)、人乳头瘤病毒(human papillomavirus,HPV)检测及联合检测(HPV+Pap或HPV+TCT)的应用情况,同时计算HPV检测人群中病毒负荷量的分布情况。结果 行Pap检查者12 967例次(53.7%),TCT检测者9 516例次(39.4%),HPV检测者5 517例次(22.9%),联合检测共计5 461例次(22.7%)。宫颈异常阳性检出率TCT高于Pap (χ2=3.866,P=0.049)。分层分析表明,HPV+Pap或HPV+TCT的联合检测法均显著优于单纯Pap或TCT检测(χ2=419.954, P=0.000;χ2=588.001,P=0.000),提示HPV检测的重要性。结论 妇科专项体检中宫颈疾病筛查方法传统,HPV检测和联合检测应用率偏低,应引起重视。同时,对于HPV负荷量≤100 RLU/CO的高危人群宜跟踪随访,以早期发现病变、降低宫颈癌发病风险。