Risk factors for cancer of the cervix in a rural Chinese population

Correlation of menstrual hygiene management with cervical intraepithelial neoplasia and cervical cancer

Purpose

To find the correlation of menstrual hygiene management (MHM) with cervical intraepithelial neoplasia and cervical cancer.

Materials and Methods

This case-control study was conducted in a tertiary care teaching hospital for 1 year. One hundred cases (CIN or cervical cancer) and 135 controls (normal cervical cytology, Swede's score below 5, or normal cervical histology) were surveyed about MHM practices through a predesigned, semi-structured questionnaire by interview method. Data were analyzed on SPSS version 17.0 statistical analysis software through Chi-square test and bivariate regression analysis.

Results

All Poor MHM practices except frequency of change of absorbent were significantly more commonly seen in women with CIN or Cervical cancer as compared to controls (P < 0.001). The bivariate regression analysis showed that old age, illiteracy, and the use of old cloth are significant risk factors for cervical cancer.

Conclusion

Poor menstrual hygiene practices of using old cloth and disposal in open are significant risk factors of cervical cancer. Good MHM practices should be widely publicized and implemented in the community to reduce the risk of cervical cancer.

A questionnaire based survey to assess knowledge and practice of health care workers regarding genital hygiene: from a rural tertiary hospital in India

PURPOSE

Maintaining good genital hygiene is an important component in reducing human papilloma virus (HPV) infections and its sequelae such as cervical pre-cancer and cancer. Awareness on the exact practice of maintaining genital hygiene is important as they are different in men and women, and both are equally important in reducing genital HPV infections.

STUDY DESIGN

A questionnaire based survey was undertaken to assess knowledge and practice of cervical cancer and its relationship with genital hygiene. Interns, post graduate students, consultants and nurses were invited. Domain based assessment was done. Correlation between the domains was performed using Pearson's coefficient.

RESULTS

87 respondents completed the questionnaire. 6 domains on awareness of physical and genital hygiene, cervical cancer causation and prevention, health education and personal experience of cervical cancer were explored. In the awareness domains, the response was uniformly poor in 45-50% of respondents. Nurses had poor knowledge in every domain of the questionnaire.

CONCLUSIONS

There is an urgent need to improve and bridge the gap of knowledge and practice in hygiene and cervical cancer. This is necessary since nurses and interns are the first line for disseminating proper information to the general public. Webinars, seminars and continued medical education (CME) programs must be included in the training curricula to impart knowledge on genital hygiene and cervical cancer.

Systematic literature review of risk factors for cervical cancer in the Chinese population

Objectives:

Human papillomavirus is the necessary cause of cervical cancer, in particular the human papillomavirus-16/18 strains, which have been detected in ~70% of all cervical cancer cases worldwide. This study aims to assess whether other cofactors, which might be specific for the Chinese population, are involved in the development of cervical cancer. These findings may support the future direction of cervical cancer prevention.

Study Design:

Systematic literature review.

Methods:

The following databases were searched: MEDLINE, MEDLINE-IN-PROCESS, EMBASE, China National Knowledge Infrastructure, Wanfang Data and Chongqing VIP Information. The target population were adolescents or adults from mainland China. All observational studies irrespective of intervention or comparator reporting risk factors for cervical cancer were included. The Newcastle-Ottawa Scale was used to assess study quality. The impact of each outcome was reported in numerical terms.

Results:

A total of 2,676 articles were screened. A total of 21 articles met the inclusion criteria. All studies were case-controlled designs mostly conducted in hospitals of South-Eastern China. A total of 18 studies reported lifestyle behaviours as significant influencing factors in the development of cervical cancer. Sexual behaviour, gestational factors, screening history, disease history and socio-demographics status were reported as significant risk factors for cervical cancer development.

Conclusion:

This review provides an up-to-date insight of current cervical cancer risk factors in China. Due to the heterogeneity of the results, further evaluation is recommended to determine the association of these risk factors to the overall risk of cervical cancer.

The association between methylated CDKN2A and cervical carcinogenesis, and its diagnostic value in cervical cancer: a meta-analysis

Background

Cervical cancer is the second deadliest gynecologic malignancy, characterized by apparently precancerous lesions and cervical intraepithelial neoplasia (CIN), and having a long course from the development of CIN to cervical cancer. Cyclin-dependent kinase inhibitor 2A (CDKN2A) is a well-documented tumor suppressor gene and is commonly methylated in cervical cancer. However, the relationship between methylated CDKN2A and carcinogenesis in cervical cancer is inconsistent, and the diagnostic accuracy of methylated CDKN2A is underinvestigated. In this study, we attempted to quantify the association between CDKN2A methylation and the carcinogenesis of cervical cancer, and its diagnostic power.

Methods

We systematically reviewed four electronic databases and identified 26 studies involving 1,490 cervical cancers, 1,291 CINs, and 964 controls. A pooled odds ratio (OR) with corresponding 95% confidence intervals (95% CI) was calculated to evaluate the association between methylated CDKN2A and the carcinogenesis of cervical cancer. Specificity, sensitivity, the area under the receiver operating characteristic curve, and the diagnostic odds ratio were computed to assess the effect of methylated CDKN2A in the diagnosis of cervical cancer.

Results

Our results indicated an upward trend in the methylation frequency of CDKN2A in the carcinogenesis of cervical cancer (cancer vs control: OR =23.67, 95% CI =15.54–36.06; cancer vs CIN: OR =2.53, 95% CI =1.79–3.5; CIN vs control: OR =9.68, 95% CI =5.82–16.02). The specificity, sensitivity, area under the receiver operating characteristic curve, and diagnostic odds ratio were 0.99 (95% CI: 0.97–0.99), 0.36 (95% CI: 0.28–0.45), 0.93 (95% CI: 0.91–0.95), and 43 (95% CI: 19–98), respectively.

Conclusion

Our findings indicate that abnormal CDKN2A methylation may be strongly correlated with the pathogenesis of cervical cancer. Our results also demonstrate that CDKN2A methylation might serve as an early detector of cervical cancer. These findings require further confirmation.

Health Beliefs and Behaviour of Cervix Cancer Patients

When people fall prey to a chronic disease they develop their own formulations about the disease. Patients often hold a variety of beliefs about causes, consequences, control and outcomes of the disease. This study examines illness beliefs and health seeking behaviour of educated, uneducated, rural and urban women suffering from the cancer of cervix. A control group (of non–patients) was also studied. The findings revealed that individual and psychosocial causes were more strongly represented in the belief system of patients than environmental or supernatural causes. The perceived consequence of illness was negatively correlated with the degree of social support available to patients. Patients characterised by a high level of social support strongly believed that their disease was in control of either “self ” or “doctor”. They resorted more to “approach–coping” strategy, experienced lesser pain and severity of illness, and expressed greater hope for a disease free life than patients characterised by low social support.

Female genital cutting: confronting cultural challenges and health complications across the lifespan

Female genital cutting affects over 140 million women worldwide. Prevalent in certain countries of Africa and the Middle East, the practice continues among immigrants to industrialized countries. Female genital cutting is a deeply rooted tradition that confers honor on a woman and her family, yet also a traumatic experience that creates significant dermatological, gynecological, obstetric and infectious disease complications. Little is known about postmenopausal health in cut women. The international community views this practice as a human rights violation. In addition to genital health complications, the medical community must confront an understudied concern of what happens as this population ages. These challenges must be addressed to provide optimal care to women affected by female genital cutting.

Evaluation of the nationwide cervical screening programme in Thailand: a case-control study

OBJECTIVES

To evaluate the effectiveness of the Pap smear screening programme in Thailand in the prevention of invasive cervical cancer.

SETTING

Four tertiary hospitals, in two provinces of north-east Thailand.

METHODS

A hospital-based case-control study of women aged 30-64, who were resident in north-east Thailand. A total of 130 women with a diagnosis of invasive cervical cancer were compared with two groups of controls: a) hospital controls, b) hospital patient companions. Information on risk factors for cervical cancer and history of screening by cytology (Pap smear) were collected using a structured interview.

RESULTS

Eighty percent of control subjects reported having had a Pap test in the past, and some two-thirds within the three years before interview. There was a significant protective effect for multiple (6+) previous screening tests as reported by 20% of controls. When women who had tests less than six months prior to the study were excluded, there was a strong, significant protective effect of the number of tests (for 1-5 tests: OR = 0.45 95% CI = 0.25 to 0.84, and for 6+ tests: OR = 0.29 95% CI = 0.11 to 0.82). Tests carried out 1-2 years and 3+ years before diagnosis were associated with an OR of 0.27 (95% CI = 0.13-0.56) and 0.42 (95% CI = 0.20-0.88), respectively.

CONCLUSIONS

The cervical screening programme in north-east Thailand has achieved excellent coverage and is preventing cervical cancer. Women who have been screened multiple times are at substantially lower risk than those only screened a few times suggesting that the quality of the screening could be improved.

Child marriage in the United States and its association with mental health in women

OBJECTIVE

Despite the devastating impact of child marriage (marriage before the age of 18 years) on health, no study has yet evaluated its impact on mental health in the general adult population. This article presents nationally representative data on the prevalence, sociodemographic correlates, and psychiatric comorbidity of child marriage among women in the United States.

METHODS

Data were drawn from the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions. We limited our analyses to the sample of women (N = 24 575) with a known age at first marriage, of whom 18 645 had been or were presently married.

RESULTS

The prevalence of child marriage among women was 8.9%. Demographic factors associated with child marriage were black and American Indian/Alaska Native ethnicities, age at interview of >45 years, low educational level, low income, and living in the South and rural areas of the United States. The overall lifetime and 12-month rates of psychiatric disorders were higher for women who married as children, compared with women who married as adults. In addition, women who married as children were more likely to seek and access health services, compared with women who married in adulthood.

CONCLUSIONS

Child marriage increases the risk of lifetime and current psychiatric disorders in the United States. Support for psychiatric vulnerabilities among women married in childhood is required.

Health consequences of child marriage in Africa

Despite international agreements and national laws, marriage of girls <18 years of age is common worldwide and affects millions. Child marriage is a human rights violation that prevents girls from obtaining an education, enjoying optimal health, bonding with others their own age, maturing, and ultimately choosing their own life partners. Child marriage is driven by poverty and has many effects on girls' health: increased risk for sexually transmitted diseases, cervical cancer, malaria, death during childbirth, and obstetric fistulas. Girls' offspring are at increased risk for premature birth and death as neonates, infants, or children. To stop child marriage, policies and programs must educate communities, raise awareness, engage local and religious leaders, involve parents, and empower girls through education and employment.

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.

Time trends in cancer mortality in China: 1987-1999

A first analysis of time trends in cancer mortality in China at the national level is presented. Using a joinpoint regression model, based on data from a national mortality routine reporting system in China (CHIS), time trends in mortality for 9 major cancers are analyzed. Between 1987 and 1999, the age-standardized mortality rates for all cancers combined declined slightly in rural areas but have increased since 1996 in urban areas. The mortality rates for cancers in oesophagus, stomach, cervix uteri, leukaemia (except for urban males after 1996) and nasopharynx declined, while lung cancer and female breast cancer showed significant increasing trends in both urban and rural areas and for both sexes. Cancers of the colon-rectum and liver had different trends in mortality in urban and rural populations. The trends in age-specific mortality rates suggest some different trends in the younger population, which may presage future overall trends, for example, increasing mortality from cancer of the cervix. The observed trends primarily reflect the dramatic changes in socioeconomic circumstances and lifestyles in China in the last 2 decades. Tobacco smoking remains a major problem, with increases in mortality from lung cancer. The improvements in socioeconomic status, diet and nutrition may be responsible for the declining risk of some cancers (oesophagus, stomach and nasopharynx), while increasing the risk for others (breast and colon-rectum). Screening programs (especially for cervix cancer), and more available and better facilities for cancer therapy, may have helped to reduce mortality for several cancers. The large increases in the absolute number of deaths that resulted from the increasing and aging population are much more important in determining the future cancer burden than any changes due to change in risk, emphasizing the increasing importance of cancer as a health problem in the 21st century in China.

Risk factors of invasive cervical cancer in Mali

BACKGROUND

Cervical cancer is the most common cancer in women in Mali and the second commonest cause of cancer mortality.

METHODS

As part of an international effort to evaluate the role of human papillomavirus (HPV) in the aetiology of cervical cancer, we conducted a hospital-based case-control study in three medical centres in Bamako during 1994-1995. A total of 82 cases (invasive cervical cancer patients) and 97 controls matched to the cases for age were included. Information on risk factors was collected through personal interview. Serum antibodies to HPV 16, 18 and 31 virus like particles (VLP) were detected using ELISA assays. Polymerase chain reaction was used to detect HPV DNA in frozen biopsies of cases.

RESULTS

Human papillomavirus 6, 18, 31 VLP were detected in 60.4% of cases and 45.4% of controls (P = 0.03). Overall, HPV DNA was identified in 96.9% of the cervical cancer cases. Risk factors for cervical cancer were parity >10 versus <5 children ([odds ratio] OR = 4.8, 95% CI : 1.5-14.7), never having practised vaginal douching (OR = 17.6, 95% CI : 4.2-74.7), re-using home-made feminine napkins (OR = 45.9, 95% CI : 8.8-238.7) and having a husband with more than two wives (OR = 5.3, 95% CI : 1.3-21.3).

CONCLUSIONS

These data provide further evidence on the role of HPV in cervical cancer and show that high parity and poor genital hygiene conditions were the main co-factors for cervical cancer in this population with prevalent HPV infection.

[Precancerous lesions of the uterine cervix in cameroonian women. Cytological and epidemiological aspects of 946 cases]

OBJECTIVE

The aim of this study was to present the cytological and epidemiological aspects of precancerous lesions of the uterine cervix of women living in the two first cameroonian cities (Yaounde and Doubla).

MATERIAL AND METHODS

The material was made of pap smears registrar of the Yaounde Central Hospital pathological laboratory and the reports of cervical cancer screening from Douala and Yaounde within a period of five years (1st January 1994 to 31st December 1998). We recruited all cases showing a precancerous lesion of the uterine cervix. For each case, we noted: the type of lesion, the age of the patient, the age at the first sexual intercourse, the age at the first delivery, the number of pregnancies, the parity, the marital status, the socioeconomical class.

RESULTS

From a total of 13524 pap smears done, 946 (7%) have shown precancerous lesions. 70% of these were high grade while 30% were low grade. These lesions were observed at all age from the range of 11 to 15 years. All women showing these lesions had had sexual intercourse. 30% of these lesions were noted among women who have had their first sexual intercourses between 10 and 15 years. 40% were observed among women who have had their first sexual intercourses between 16 and 18 years. 66% among women who have had their first delivery between 13 and 21 years. 92% are observed among women who have had more than five pregnancies, more than five parities; 54% among women who are married and 76% among bachelors and widows; 64% among women with low socioeconomical status; 9% among women with high socioeconomical status.

CONCLUSION

Many cameroonian women are prone to cervical cancer.

Risk factors for pre-cancerous lesions of the cervix

Studies on risk factors for pre-cancerous lesions of the uterine cervix have shown strong association with sexual practice. Women with multiple sexual partners and intercourse at early age are at high risk. A role of male partners in further enhancing the risk has been identified. All these support the hypothesis relating to a sexually transmissible aetiological agent. An extensive review of the literature on the risk factors for pre-cancerous lesions of cervix has been carried out. The risk factors were grouped into genital, sexual, chemical, dietary and life factors. Human papilloma virus (HPV) is the major infectious aetiological agent associated with the development of pre-cancerous lesions of cervix. Other co-factors such as multiple sexual partners of the male as well as the female and early age of first intercourse are also involved at the critical aetiological step of progression from low-grade to high-grade lesions. The role of other infectious agents in terms of supportive or interactive effects is not clear. No independent effect for herpes simplex virus 2 on risk is observed. Other risk factors include cigarette smoking, oral contraceptive usage, certain nutritional deficiencies and poor personal hygiene. However, it is not clear whether these factors operate independently from HPV. There is no consistency in the independent effect of these factors on the development of low- to high-grade lesions of cervix. There is a similarity in the patterns of risk between pre-cancerous lesions of the cervix and cervical cancer. Monogamy, late commencement of sexual activity, personal hygiene and use of barrier contraceptive methods help towards primary prevention. In the long-term, primary prevention of cervical neoplasia through HPV immunization of population may be a possibility.

The viral origin of cervical cancer in Rabat, Morocco

In Northern Africa, cervical cancer is the second most common cancer among women. The diagnosis is usually made in advanced stages, and mortality is high, yet few studies have investigated the role of human papillomavirus (HPV) and other risk factors in the etiology of cervical cancer. A hospital-based case-control study was completed at the Institut National d'Oncologie (INO) in Rabat, Morocco. The study included 214 cases of invasive cervical cancer and 203 controls. A structured questionnaire was used to investigate known and suspected risk factors for cervical cancer. A GP 5+/6+ polymerase chain reaction system was used to detect the presence of HPV DNA and HPV type distribution. Probes for 30 HPV types were used in one research laboratory. HPV DNA was the central risk factor and accounted for the large majority of the cases. The adjusted odds ratio (ORa) for any HPV was 61.6 (95% CI, 29.2-130) and the corresponding HPV attributable fraction (AF) was 92%. Among cases of cervical cancer, HPV 16 was the most common type (67.7%) followed by HPV 18. The HPV type-specific prevalence was similar for squamous cell carcinomas and adenocarcinomas. In multivariate adjusted or HPV-stratified analyses, in addition to the strong effect of HPV, other risk factors identified were sexual intercourse with multiple partners before the age of 20 and low socio-economic status. Use of oral contraceptives for 5 or more years and high parity were also found to be related to cervical cancer. Screening was rare in this population but offered substantial protection against cervical cancer. In Morocco, cervical cancer is a late sequel of a viral infection with certain HPV types. Developing screening programs for preneoplastic cervical lesions is a public health priority. When available, HPV vaccination would offer a relevant alternative for preventing cervical cancer.

Epidemiology of trichomonas vaginalis. A prospective study in China

BACKGROUND AND OBJECTIVES

Trichomonas vaginalis infection is probably one of the most common sexually transmitted diseases. The epidemiology of this disease has long been ignored, and not much is known about its natural history and risk factors.

GOALS

The authors conducted this study to define the incidence rates of T. vaginalis infection and to investigate risk factors for the infection.

STUDY DESIGN

A prospective study was carried out on a cohort of 16,797 women followed up from 1974 to 1985 within the framework of a cervical screening program in Jingan, China. Personal interviews were conducted by trained interviewers.

RESULTS

A total of 1489 new cases of T. vaginalis infection were diagnosed with 132,946 person-years of observation. In a multivariate analysis, the increased risk was associated with multiple sexual partners (P = 0.0124) and greater number of induced abortions (P = 0.0028). The relative risks were 1.3 (95% confidence interval [CI], 1.1 to 1.5) for smokers and 1.5 (95% CI, 1.2 to 2.0) for those who drink alcohol. An inverse relationship was observed in older women and in women with cervical atrophy.

CONCLUSIONS

This study confirmed the relationship between T. vaginalis and multiple sexual partners and suggests that the risk for T. vaginalis also may be related to life-style risk factors.

Trichomonas vaginalis and cervical cancer. A prospective study in China

The relationship between Trichomonas vaginalis infection and cervical cancer was investigated prospectively in a cohort of 16,797 women aged 25 years or more who were followed from 1974 to 1985 within the framework of a cervical screening program in Jingan, China. Personal interviews were conducted by trained interviewers when the women first entered the screening program. At initial screening, 421 (2.51%) women had a positive cytologic diagnosis of T. vaginalis infection. Ninety-nine incident cases of pathologically confirmed squamous cell carcinoma were identified from the cohort, with a total of 140,018 person-years of observation. T. vaginalis infection was found to contribute to the risk of cervical cancer, as determined by crude estimates and after adjustment for potential confounding effects. In a multiple proportional hazards model, the relative risk for cervical cancer was 3.3 (95% confidence interval: 1.5 to 7.4) among women with T. vaginalis infection. Furthermore, in the multivariate analysis, increased risk of cervical cancer was associated with the following factors: number of extramarital sexual partners of both the subjects and their spouses, cigarette smoking, and irregular menstruation. Having a large number of negative Pap smears was associated with lower risk. This study suggests that there might be an association between T. vaginalis infection and the risk of cervical cancer, but only 4 to 5% of cervical cancer in Chinese women may be attributable to T. vaginalis infection.

Urbanization gradients and cancer mortality in Uruguay, 1988-1992

Cancer deaths occurring in Uruguay in the period 1988-1992 were classified by site, sex and residence according to the ninth version of the International Classification of Diseases (ICD-9), in order to analyze gradients of urbanization. For this purpose, Uruguayan counties were classified as rural, suburban and urban, using population density as an ordinal indicator of the degree of urbanization. Significant increasing trends with urban excess were observed for cancers of the colon, rectum, lung and female breast. In addition, this study showed significant urban deficits for esophageal, gastric and uterine cancers, contrasting with previous studies. These differences seem to be real rather than artifactual due to misclassification. The study thus provides interesting new findings concerning urban differences between developed communities and a partially developing country.

Human papillomavirus types 16 and 33, herpes simplex virus type 2 and other risk factors for cervical cancer in Sichuan Province, China

Cancer of the cervix is relatively common in China, but has been investigated epidemiologically in only a few studies. In the hospital-based case-control study reported here, we investigated the role of various lifestyle and dietary factors, as well as infection with human papillomavirus (HPV) types 16 and 33 and herpes simplex virus type 2 in the aetiology of invasive cervical cancer. The study was conducted in Sichuan province, and involved 101 cases with histologically-confirmed cervical cancer recruited from the gynaecological oncology clinic of the West China University Hospital, and 146 controls recruited from patients attending the gynaecology clinic of the same hospital. Risk of cervical cancer was greatly increased in association with infection with HPV 16/33, the adjusted odds ratio for those with evidence of infection being 32.9 (95% CI 7.7-141.1). In contrast, infection with HSV 2 was not associated with a significantly altered risk of cervical cancer. Indices of sexual history and of dietary habits also showed no association with risk of cervical cancer, while good personal and genital hygiene were associated with markedly reduced risk. Although the results of this study are consistent with a causal role for HPV in the aetiology of cervical cancer, bias or increased viral expression following malignant transformation cannot be excluded as explanations for the strong positive association.

Detection of human papillomavirus (HPV) in genital warts and carcinomas by DNA in situ hybridization in Chinese patients

A series of 51 genital biopsies from normal epithelium, condylomata acuminata, leucoplakia and squamous cell carcinoma from Chinese male and female patients were analysed for the presence of human papillomavirus (HPV) types 6, 11, 16 and 18 by DNA in situ hybridization. All of the nine genital condyloma acuminata were positive for HPV DNA, in which HPV 6 was found in six cases, HPV 11 in two cases and HPV 18 in one case. Twelve out of the 21 cases (57.1% of the total) of cervical squamous cell carcinoma were shown to contain HPV DNA; HPV 16 was found in nine cases, HPV 18 in two cases and HPV 16/18 in one case. Present results support the earlier concept that HPV 6/11 are closely associated with benign genital lesions, and HPV 16/18 are mostly confined to higher grade of intra-epithelial neoplasias and carcinoma.

Epidemiology of human papillomavirus (HPV) infections and their associations with genital squamous cell cancer. Review article

Reliable assessment of the epidemiology of genital HPV infections is hamphered by a number of technical problems. Because of the lack of tissue-culture systems, methods based on morphological approaches (colposcopy, cytology and histopathology) play a central role in HPV diagnosis. Even DNA-hybridization techniques and the recently introduced DNA amplification with PCR are extremely difficult to standardize, and are thus subject to major interlaboratory variation. Further confusion in the field is created by the complex biological behaviour of HPV infections. As established by the long-term prospective follow-up study of over 500 women which has been running in Kuopio since 1981, clinical progression and regression are significantly related to the grade of the lesion at the time of diagnosis (p less than 0.00001, and p = 0.0005, respectively), as well as to the type of HPV (p = 0.0012). Most importantly, however, genital HPV infections seem to run an extremely fluctuating course, passage from manifest to subclinical or latent infection being frequently encountered in individual patients when examined at 6-month intervals over prolonged periods. This explains the significantly divergent prevalence figures reported in different series (ranging from 2% to 80%), which are completely dependent on the technique used to analyse the presence of HPV, i.e. whether a) PAP smear, b) biopsy, c) DNA hybridization, or d) PCR amplification. The first two are capable of disclosing only manifest (clinical) infections, the latter two also the latent ones. In an unselected population of 22-year-old Finnish females, the prevalence of clinical HPV infections was about 3 per cent, and the adjusted annual incidence was 8.0 per cent. According to estimates of the life-time risk, up to 79% of Finnish females will contract at least one HPV infection between the ages 20 to 79 years. When related to the long-term trends in invasive cervical cancer in Finland, it is evident that this 79% life-time risk of becoming HPV-infected or even the observed 15% clinical progression rate for HPV infections in the prospective follow-up study by no means signifies an identical risk of developing cervical cancer (i.e. 0.79 x 0.15 = 11%). It seems likely that in countries where mass-screening programmes exist (and precancer lesions are traced), the high prevalence of HPV infections is not necessarily reflected as an increased prevalence of invasive cervical carcinomas. The distinction of lesions at risk for malignant transformation from those regressing spontaneously will have major implications in therapeutic considerations of genital HPV infections.