A STUDY OF THE AETIOLOGY OF CARCINOMA OF THE CERVIX UTERI

Does Male Circumcision Reduce Women's Risk of Sexually Transmitted Infections, Cervical Cancer, and Associated Conditions?

Background: Male circumcision (MC) is proven to substantially reduce men's risk of a number of sexually transmitted infections (STIs). We conducted a detailed systematic review of the scientific literature to determine the relationship between MC and risk of STIs and associated conditions in women. Methods: Database searches by "circumcision women" and "circumcision female" identified 68 relevant articles for inclusion. Examination of bibliographies of these yielded 14 further publications. Each was rated for quality using a conventional rating system. Results: Evaluation of the data from the studies retrieved showed that MC is associated with a reduced risk in women of being infected by oncogenic human papillomavirus (HPV) genotypes and of contracting cervical cancer. Data from randomized controlled trials and other studies has confirmed that partner MC reduces women's risk not only of oncogenic HPV, but as well Trichomonas vaginalis, bacterial vaginosis and possibly genital ulcer disease. For herpes simplex virus type 2, Chlamydia trachomatis, Treponema pallidum, human immunodeficiency virus and candidiasis, the evidence is mixed. Male partner MC did not reduce risk of gonorrhea, Mycoplasma genitalium, dysuria or vaginal discharge in women. Conclusion: MC reduces risk of oncogenic HPV genotypes, cervical cancer, T. vaginalis, bacterial vaginosis and possibly genital ulcer disease in women. The reduction in risk of these STIs and cervical cancer adds to the data supporting global efforts to deploy MC as a health-promoting and life-saving public health measure and supplements other STI prevention strategies.

Reprint of "Cancer of the cervix: A sexually transmitted infection?"

When mortality patterns for cancer of the uterine cervix were compared with trends in incidence of sexually transmitted diseases in both England and Wales and in Scotland, there were striking associations between the temporal, social class, occupational, and geographic distributions of these diseases. The data suggest that exposure to sexually transmitted infection is an important determinant of cervical cancer. Although they are still young, women born after 1940 are already experiencing increased cervical-cancer mortality. If cervical-cancer prevention and therapy remain unchanged, this generation's high risk of death from cervical cancer will probably continue to operate throughout their lives.

Opportunistic screening for cervical cancer in a tertiary hospital in Karnataka, India

The incidence and mortality of cervical cancer remains high in India even after sixty years of introduction of the Pap smear (cervical cytology) which is an effective means of identifying preinvasive lesions of carcinoma cervix. The morbidity and mortality due to cervical cancer has come down drastically in countries with well established screening programmes at national level. This study aims at screening women for cervical cancer opportunistically during their visit to hospital and to study various types of neoplastic and non-neoplastic lesions of the cervix by cervical smear study (Pap smear study). In the present study, a total of 350 cervical smears were studied. The age of patients ranged from 19 years to 80 years with mean age being 37.5 years. Out of 350 cases, the diagnosis of neoplasia was given in 43 cases and 258 cases were diagnosed as inflammatory smears. Forty-cases were normal and 9 cases were inadequate to evaluate. Forty-three patients who were found to have neoplastic lesions on cytology were referred for further investigations like colposcopy and biopsy to confirm the diagnosis and avail proper treatment. Limitation of the present study was small sample size as all female patients aged between 20 and 60 years visiting hospital were not included in the screening, other screening tests like VIA (visual inspection with acetic acid test) and HPV DNA (human papilloma virus) tests were not done. Until the time centrally organised screening programmes for cervical cancer are established in India, arrangements should be made for hospital based opportunistic screening for all women attending hospital. The cost effectiveness of different screening tests for cervical cancer should be evaluated.

Cervical carcinoma and sexual behavior: collaborative reanalysis of individual data on 15,461 women with cervical carcinoma and 29,164 women without cervical carcinoma from 21 epidemiological studies

High-risk human papillomavirus (HPV) types cause most cervical carcinomas and are sexually transmitted. Sexual behavior therefore affects HPV exposure and its cancer sequelae. The International Collaboration of Epidemiological Studies of Cervical Cancer has combined data on lifetime number of sexual partners and age at first sexual intercourse from 21 studies, or groups of studies, including 10,773 women with invasive cervical carcinoma, 4,688 women with cervical intraepithelial neoplasia grade 3 (CIN3)/carcinoma in situ, and 29,164 women without cervical carcinoma. Relative risks for invasive cancer and CIN3 were estimated by conditional logistic regression. Risk of invasive cervical carcinoma increased with lifetime number of sexual partners (P for linear trend <0.001). The relative risk for > or =6 versus 1 partner, conditioned on age, study, and age at first intercourse, was 2.27 [95% confidence interval (95% CI), 1.98-2.61] and increased to 2.78 (95% CI, 2.22-3.47) after additional conditioning on reproductive factors. The risk of invasive cervical carcinoma increased with earlier age at first intercourse (P for linear trend <0.001). The relative risk for age at first intercourse < or =14 versus > or =25 years, conditioned on age, study, and lifetime number of sexual partners was 3.52 (95% CI, 3.04-4.08), which decreased to 2.05 (95% CI, 1.54-2.73) after additional conditioning on reproductive factors. CIN3/carcinoma in situ showed a similar association with lifetime number of sexual partners; however, the association with age at first intercourse was weaker than for invasive carcinoma. Results should be interpreted with caution given the strong correlation between sexual and reproductive factors and the limited information on HPV status.

The Long-Term Effects of Steroid Contraceptives

The Twelfth Oliver Bird Lecture was delivered by Professor Richard Doll, Regius Professor of Medicine in the University of Oxford, at the London School of Hygiene and Tropical Medicine on 19th March 1970. This was the last lecture to be given under the auspices of the Oliver Bird Trust, an account of which starts on page 359. Professor Doll was formerly Director of the MRC Unit of Medical Statistics, in which capacity he had exceptional experience in assessing the significance of changes in the incidences of abnormal conditions. The subject of his lecture was therefore highly appropriate to his special knowledge, as well as to current controversy and to the series of Oliver Bird lectures. The Journal of Biosocial Science is glad to publish this authoritative exposition of a most important problem.

Cervical carcinoma and reproductive factors: Collaborative reanalysis of individual data on 16,563 women with cervical carcinoma and 33,542 women without cervical carcinoma from 25 epidemiological studies

The International Collaboration of Epidemiological Studies of Cervical Cancer has combined individual data on 11,161 women with invasive carcinoma, 5,402 women with cervical intraepithelial neoplasia (CIN)3/carcinoma in situ and 33,542 women without cervical carcinoma from 25 epidemiological studies. Relative risks (RRs) and 95% confidence intervals (CIs) of cervical carcinoma in relation to number of full-term pregnancies, and age at first full-term pregnancy, were calculated conditioning by study, age, lifetime number of sexual partners and age at first sexual intercourse. Number of full-term pregnancies was associated with a risk of invasive cervical carcinoma. After controlling for age at first full-term pregnancy, the RR for invasive cervical carcinoma among parous women was 1.76 (95% CI: 1.53-2.02) for > or => or =7 full-term pregnancies compared with 1-2. For CIN3/carcinoma in situ, no significant trend was found with increasing number of births after controlling for age at first full-term pregnancy among parous women. Early age at first full-term pregnancy was also associated with risk of both invasive cervical carcinoma and CIN3/carcinoma in situ. After controlling for number of full-term pregnancies, the RR for first full-term pregnancy at age <17 years compared with > or => or =25 years was 1.77 (95% CI: 1.42-2.23) for invasive cervical carcinoma, and 1.78 (95% CI: 1.26-2.51) for CIN3/carcinoma in situ. Results were similar in analyses restricted to high-risk human papilloma virus (HPV)-positive cases and controls. No relationship was found between cervical HPV positivity and number of full-term pregnancies, or age at first full-term pregnancy among controls. Differences in reproductive habits may have contributed to differences in cervical cancer incidence between developed and developing countries.

Family physicians' knowledge of risk factors for cervical cancer

BACKGROUND

A woman's risk for cervical cancer has been used by physicians to guide the initiation and frequency of a Pap smear. The aim of this study was to determine family physicians' knowledge of risk factors for cervical cancer and perceived importance of risk in screening women.

METHODS

The self-administered questionnaire was mailed to 5000 randomly selected active members of the American Academy of Family Physicians (AAFP).

RESULTS

Data from 2748 usable questionnaires indicated the mean number of risks considered for cervical cancer was 4.5. Physician's age and the number of reported risks were inversely correlated (p = 0.0001). Female physicians reported significantly more risk factors than male physicians (p = 0.05). The number of Pap smears performed per month was positively correlated with the number of risk factors reported (p = 0.001). Only 10% of the physicians indicated that they perform a Pap smear at the same interval regardless of the risk of the woman.

CONCLUSIONS

This sample of family physicians has a limited understanding of the risk factors for cervical cancer. This was true regardless of the age, gender, training, race, geographic location, or practice setting of the responding physician. Yet the usual practice of screening for cervical cancer reported by these physicians would suggest that knowledge and use of risk factors would be a critical aspect of screening for cervical cancer.

Role of parity and human papillomavirus in cervical cancer: the IARC multicentric case-control study

BACKGROUND

High parity has long been suspected of being associated with an increased risk of cervical cancer, but previous analyses of this association have not taken the strong effect of human papillomavirus (HPV) into account. To assess the role of reproductive factors in the progression from HPV infection to cancer, we did a pooled analysis including only HPV-positive women.

METHODS

We pooled data from eight case-control studies on invasive cervical carcinoma (ICC) and two on in-situ carcinoma (ISC) from four continents. 1465 patients with squamous-cell ICCs, 211 with ISCs, 124 with adenocarcinomas or adenosquamous ICCs, and 255 control women, all positive for HPV DNA by PCR-based assays, were analysed. We calculated pooled odds ratios by means of unconditional multiple logistic regression models, and adjusted them for sexual and non-sexual confounding factors. The 95% CI were estimated by treating the odds ratio as floating absolute risk.

FINDINGS

We found a direct association between the number of full-term pregnancies and squamous-cell cancer risk: the odds ratio for seven full-term pregnancies or more was 3.8 (95% CI 2.7-5.5) compared with nulliparous women, and 2.3 (1.6-3.2) compared with women who had one or two full-term pregnancies. There was no significant association between risk of adenocarcinoma or adenosquamous carcinoma and number of full-term pregnancies.

INTERPRETATION

High parity increases the risk of squamous-cell carcinoma of the cervix among HPV-positive women. A general decline in parity might therefore partly explain the reduction in cervical cancer recently seen in most countries.

Detection of human papillomavirus in cervical biopsies of summer camp ROTC cadets with abnormal papanicolaou smears

STUDY OBJECTIVE

Human papillomavirus (HPV) infections may be the most common sexually transmitted disease (STD) among adolescents and young adults. A strong association exists for certain "high-risk" HPV-type cervical infections and subsequent evolution of cervical cancer and its precursor lesions. The objective of this study was to detect HPV in cervical biopsies of reserve officer training corps (ROTC) cadets attending a regional summer camp who had abnormal screening Papanicolaou (Pap) smears and to better define the spectrum of HPV oncogenic risk types for this population. It was hypothesized that HPV would be detected in the majority of cervical biopsies in keeping with the evolving concept of cervical cancer and its precursors as an STD and the central role of HPV in its development.

DESIGN

On arrival for summer military camp training, college women cadets underwent physical examinations that included pelvic examinations for Pap smears. Study participants completed confidential questionnaires after informed consent was obtained. Subjects, who had abnormal Pap smears as defined by reports of atypical squamous cells of undetermined significance (ASCUS) or low- or high-grade squamous intra-epithelial lesions (LGSIL or HGSIL), underwent colposcopic evaluations with cervical biopsies. Subsequently, biopsies were processed for detection of HPV-specific DNA by gel electrophoresis, chemiluminescent oligonucleotide probing, and DNA-RNA hybridization methods after polymerase chain reaction (PCR) amplification.

PARTICIPANTS

All female summer camp enrollees presented to the Madigan Army Medical Center Gynecology Clinic for complete physicals before the onset of the training program and were solicited for study inclusion.

MAIN OUTCOME MEASURES

All colposcopic biopsy specimens were evaluated for the presence of HPV DNA and subtyped if positive.

RESULTS

Representing 42 states, 95% (332) of eligible subjects participated. Mean age was 21.9 years. Racial composition included 70% white, 16% black, 4% Hispanic, 4% Asian, and 6% "other." Eighty-five percent had a history of hetero-sexual activity, with 17.7 years as the mean age at onset. Of the subjects, 12.6% reported a previous diagnosis of a sexually transmitted disease, and 7.8% (26 of 332) had abnormal Pap smears. Of these, colposcopic biopsy results were available for 25 of the 26 abnormal Pap smears. Ninety-six percent (24 of 25) of the colpobiopsies had detectable HPV. Eighty-eight percent (22 of 25) of the subjects with abnormal Pap smears had concurrent abnormal biopsy results. All of these had detectable HPV, confirmed by three different methods, and 29% had dual HPV infection. Sixty percent had "intermediate" or "high-risk" types identified by specific genotyping, 8% had "low-risk" types, and 28% had nontypable HPV.

CONCLUSIONS

The data confirm that abnormal Pap smears in this young adult college population are almost always associated with HPV infection, a significant proportion of it being other than low-risk types. The prognostic significance of type-specific cervical HPV infection still needs to be better defined in relation to potential cofactors and host immune response. However, clinicians who provide primary gynecologic care to adolescents and young adults should be aware of the high correlation between abnormal Pap smears and HPV cervical infection and should follow up the patient with the potential risk in mind.

The epidemiology of cervical carcinogenesis

Epidemiologic and laboratory data suggest that cervical cancer typically arises from a series of causal steps. Each step can be studied separately in the hope of better etiologic understanding and improved cancer prevention. The earliest identified etiologic step is infection of young women with specific types of venereally transmissible human papillomaviruses (HPVs). Cervical HPV infections often lead to low grade squamous intraepithelial lesions (mildly abnormal Pap smears). Human papillomavirus infections and their associated lesions are extremely common among young, sexually active women. The infections typically resolve spontaneously even at the molecular level within months to a few years. Uncommonly, HPV infections and/or low grade lesions persist and progress to high grade lesions. The risk factors for progression are mainly unknown but include HPV type and intensity, cell-mediated immunity, and reproductive factors. Nutritional factors or co-infection with other pathogens may also be involved at this apparently critical etiologic step between common low grade and uncommon high grade intraepithelial lesions. Except for advancing age, no epidemiologic risk factors have been found for the next step between high grade intraepithelial lesions and invasive cancer. At the molecular level, invasion is associated with integration of viral DNA. Based on worldwide research, the steps in cervical carcinogenesis appear to be fundamentally the same everywhere, with a central role for HPV infection. The importance of etiologic cofactors like smoking, however, may vary by region.

Human papillomaviruses, cervical cancer and the developing world

Carcinoma of the uterine cervix is the commonest cancer of women in the majority of developing countries; in developed countries it is much less common, as well as being less frequent than some other cancers, such as those of breast, lung and colon. The discovery of human papillomavirus (HPV) as an aetiological agent of cervical cancer (and of other anogenital malignancies) has prompted a great deal of interest in the biology and oncogenicity of this virus, including large-scale epidemiological surveys comparing the prevalence of HPV and other possible causative agents between areas of high and low incidence of cervical carcinoma. These studies have thrown up tantalizing clues concerning the virus' pathogenesis and disease associations. Sexual practices, parity, diet, smoking, other diseases (including sexually transmissible diseases) and immunogenetic characteristics may all play a contributory role in the development of cervical carcinoma. These factors may be independent of each other and of association with HPV infection. Immunization to prevent papillomavirus infection and thus cervical cancer is an attractive prospect. Although the potential in using such an approach has been demonstrated in several animal models, there are several major theoretical problems to solve before HPV vaccination becomes a practicality. Intervention to prevent exposure to other aetiological factors and to improve screening may be a more practicable strategy for reducing the burden of cervical cancer.

Implications of gynaecological abnormalities in pre-selection criteria for cervical screening: preliminary evaluation of 3602 subjects in south India

Early detection and eradication of cervical cancer and its precursor lesions through organized mass cytological screening programmes have recently gained considerable attention in developing countries. Strategies for both cost saving and effective implementation are however required for mass cervical screening in developing countries. In an early cancer detection programme conducted in South India, we analysed cytological abnormalities in 3602 women and correlated the results with other factors, including age, gynaecological complaints, number of years of married life and parity to see if pre-selection for cytologic screening was possible. Only lower grades of dysplasia were found in asymptomatic women below the age of 40 years. In asymptomatic women, malignancy and higher grades of dysplasia were confined to women with a clinically abnormal cervix only. Univariate analysis also revealed that subjects with a parity of more than 3 and a married life of more than 20 years had a significantly higher number of cytological abnormalities. However, on a multivariate analysis the increased number of marital years was not found to be an independent variable. These results suggest that asymptomatic women below the age of 40 years with a married life of less than 20 years and parity below 3, may be excluded from screening campaigns, and that pre-selection for cytologic screening is possible by introducing a programme of clinical and speculum examination of the cervix.

Primary prevention of gynecologic cancers

A shift from treatment to prevention of the three major gynecologic cancers is overdue. The traditional approach to cervical, endometrial, and ovarian cancers has been secondary or tertiary prevention--early detection and treatment or mitigation of damage, respectively. We reviewed the literature on these cancers to identify strategies for primary prevention. Cervical cancer behaves as a sexually transmitted disease. As with other such diseases, barrier and spermicidal contraceptives lower the risk of cervical cancer; the risk reduction approximates 50%. Combination oral contraceptives help prevent both endometrial and epithelial ovarian cancers. The risk of endometrial cancer among former oral contraceptive users is reduced by about 50% and that of ovarian cancer by about 30% to 60%. Weight control confers strong protection against endometrial cancer. Breast-feeding and tubal sterilization also appear to protect against ovarian cancer. Although women have a range of practical, effective measures available to reduce their risk of these cancers, few are aware of them. Without this information, women cannot make fully informed decisions about their health.

Association between cervical and penile cancers in Madras, India

A total of 4,995 cervical and 311 penile cancer cases were registered in the Madras Population-Based Cancer Registry at the Cancer Institute (WIA), Madras, India, in 1982-1990. The parameters analyzed were age at the time of diagnosis, educational level, marital status, and religion. Peak incidence of carcinoma of the cervix was seen in the age group 55-59 years. The incidence of penile cancer increased consistently with age. Among cervical cancer patients, the incidence was significantly higher among illiterates and among those who had an education for 12 years or less than among those with over 12 years of education. The incidence of cervical cancer was low among Muslim women compared to Hindu and Christian women, and penile cancer was not seen at all among Muslim men. Our results re-emphasize the importance of circumcision in the reduction of the risk of both cervical and penile cancers.

Epstein-Barr virus activating principle in husbands' semen of cervical cancer patients

A short-term in vitro assay for detecting tumor promoter activity has been cultivated utilizing the induction of Epstein-Barr virus early antigen (EBV-EA) in EBV genome-carrying human lymphoblastoid cell line (Raji cell) system. By using this system, we found that some of human semen samples possessed a marked capacity to induce EBV-EA, suggesting possible tumor promotor activity of semen. In the present study, 60 semen samples obtained from husbands of cervical cancer patients and 90 control samples were incubated with Raji cells for 48 h, and EBV-EA-expressing cells detected by indirect immunofluorescence were counted. The percentages of EBV-EA-positive cells treated with semen of cervical cancer patients' husbands (8.17 +/- 5.43%) were significantly higher than those of controls (5.23 +/- 5.91%). Since most of EBV-EA expressing effect on Raji cells show overlapping with tumor promotor activities, our present results implies the circumstantial association of seminal EBV-EA inducing activity with occurrence of human cervical cancer.

Barrier methods of contraception and the risk of cervical neoplasia

The relationship between the use of barrier contraception methods and the risk of cervical neoplasia was analyzed using data from a case-control study conducted in the greater Milan area, northern Italy. A total of 367 cases of invasive cancer under 60 years of age were compared with 323 subjects in hospital for acute conditions unrelated to any of the established or suspected risk factors for cervical cancer, and 316 cases of cervical intraepithelial neoplasia were compared with 258 outpatient controls. Ever-use of barrier methods (condom and diaphragm) was reported by 6% of the cases of invasive cancer and 12% of hospital controls. Corresponding values for intraepithelial neoplasia were 16% for cases and 22% for outpatient controls. Considering the total use of barrier methods, compared to never use, the relative risk of invasive cervical cancer was 0.4 (95% confidence interval 0.2-0.9) and decreased with duration of use (chi 2(1), trend = 5.18, p = 0.02). Likewise, use of barrier methods lowered the risk of intraepithelial neoplasia; the estimated relative risks were 0.9 in users for less than two years and 0.6 for two or more (chi 2(1), trend = 4.61, p = 0.03). Although the protection for invasive cancer appeared to be greater at older ages and in multiparous women, the relative risks were not significantly heterogeneous in various strata of parity, number of sexual partners, oral contraceptive use and history of Pap smears.

A case-control study of cervix cancer in Singapore

Cervix cancer is about twice as common in Asia as in the Western world and its incidence varies among different Asian ethnic groups. A study based in Singapore, the population of which comprises Chinese, Indians and Malaysians, offers the opportunity to evaluate whether the same risk factors are important in this part of the world as in the West. A total of 135 cases and an equal number of controls were interviewed and details concerning reproductive and sexual history, smoking, hygiene, socio-economic status and education were collected. Seventy-three cases had invasive cancer while 62 had micro-invasive disease or CIN III. The most important risk factors were parity and number of sexual partners. Smoking was rare in cases and controls and did not appear to be an important determinant of risk. Of the socio-economic factors, education appeared most predictive and lowered the risk. Age at first intercourse was strongly correlated with education (positively) and parity (negatively), but not with number of sexual partners. Biopsies were available for HPV DNA analysis in 38 cases and 37% were positive, mostly for HPV type 16. All these factors gave similar risks in invasive and preinvasive disease.

Risk factors for cervical cancer in Greenland and Denmark: a population-based cross-sectional study

The incidence of cervical cancer in Greenlandic women aged 20-39 years is nearly 6 times higher than in Danish women of the same age. Possible determinants of cervical cancer incidence were investigated in a population-based cross-sectional study. From Nuuk (Greenland) and Nykøbing Falster (Denmark) a sample of 800 women aged 20-39 years was drawn at random. A total of 586 and 661 women were studied in Greenland and Denmark, respectively. All underwent a personal interview. In Greenland, 13% of the women reported first intercourse before the age of 14 in contrast to 3.5% in Denmark, and nearly 85% of the Greenlanders had their sexual debut before the end of the 16th year of age whereas this applied to only 45% of the Danish women. The prevalence of women with 0-1 lifetime sexual partner was 20.4% in Denmark, and only 1.7% in Greenland. In contrast, 53.2% of the Greenlandic women reported more than 20 partners and 22.4% more than 40 partners. The corresponding figures for Denmark were 3.6% and 0.3%, respectively. In Greenland the most common contraceptive method was the use of intra-uterine devices (73.6%), whereas, in Denmark, oral contraceptive use was most frequent (87.9%). Few Greenlanders had ever used "barrier" contraceptives (diaphragm: 1.4%; condom: 18.1%) compared to Denmark (diaphragm: 10.1%; condom: 53.9%). As many as 87.4% were current smokers in Greenland (Denmark: 53.6%) and 5.6% claimed to have never smoked, whereas this applied to 35.3% in Denmark. The indications of a higher sexual activity (multiple partners, early age at first intercourse) in Greenland compared to Denmark are in line with the observed higher rates of sexually transmitted diseases and with the hypothesis that differences in cervical cancer incidence between Greenland and Denmark are determined by aspects of sexual background.

Reproductive factors and the risk of invasive and intraepithelial cervical neoplasia

The relation between reproductive factors and cervical neoplasia was evaluated in a case-control study of 528 cases of invasive cancer compared with 456 control subjects in hospital for acute conditions unrelated to any of the established or suspected risk factors for cervical cancer, and of 335 cases of cervical intraepithelial neoplasia compared with 262 outpatient controls. The risk of invasive cervical cancer increased with number of livebirths, the estimated multivariate relative risk (RR) being 4.39 in women with five or more births compared with nulliparous women. There was also an inverse relation with age at first livebirth (RR = 0.42 for greater than or equal to 30 vs. less than 20 years) which, however, disappeared after inclusion of parity in multiple logistic regression analysis. Likewise, cases of invasive cervical cancer tended more frequently to report induced abortions. However, this association was not statistically significant after allowance for confounding factors, including parity. No relation emerged with number of spontaneous abortion and age at last pregnancy. When the interaction between parity and sexual habits was analysed, the relative risk increased in subsequent strata of parity with increasing number of sexual partners or decreasing age at first intercourse, thus suggesting an independent effect of sexual and reproductive factors, and hence multiplicative on the relative risk of invasive cervical cancer. No consistent association emerged between the risk of intraepithelial cervical neoplasm and parity, number of abortions and age at first or last birth.

An epidemiological study on marital status and cancer incidence

The relationship between marital status and cancer incidence was examined based on 49,191 incident cases aged 30 or over in 1980-1984 by using the data from Aichi Cancer Registry and census data. Although married and widowed people did not show increased incidence for any cancer site studied, single and divorced people showed statistically significantly increased or decreased risks for several sites of cancer. Single males showed an increased risk for esophageal cancer and a decreased risk for lung cancer. Divorced males showed increased risks for cancers of the mouth & pharynx, esophagus, liver, skin and brain. Single females showed increased risks for cancers of the esophagus, stomach, small intestine, liver, pancreas, lung, breast, corpus uteri, ovary & fallopian tube and other female genital organs and a decreased risk for cervical cancer. Divorced females showed increased risks for cancers of the larynx, breast, all parts of uterus and cervix uteri and a decreased risk for biliary tract cancer. The increased risk for breast cancer in single females was more pronounced in older age groups and the increased risks for several sites of cancer in divorced people were more pronounced in younger age groups. These findings may be partly explained by differences in reproductive factors and life style, especially smoking and drinking habits.

Sexual, reproductive and contraceptive risk factors for carcinoma-in-situ of the uterine cervix in Sydney

Sexual, reproductive and contraceptive risk factors were investigated in a matched community-based case-control study of carcinoma-in-situ of the uterine cervix in Sydney. The risk was related strongly to the number of sexual partners: women who had had seven or more sexual partners in a lifetime had a six-fold increased risk compared with those with one or no partner. Early age at first sexual intercourse was also a risk factor, but this effect was reduced substantially after adjustment for the number of partners, with only a two-fold excess risk persisting for those with first intercourse before the age of 16 years as compared with those whose first sexual intercourse was at the age of 25 years or later. The long-term use of oral contraceptive agents was associated with an elevated risk (relative risk, 2.3 for more than six years of use); this effect was maintained for both oestrogen and progestogen doses. The risk increased with the number of induced abortions that had been undergone (relative risk, 2.2 for two or more abortions), but this effect was not statistically significant. A protective effect was found for women who had had a tubal ligation, for those who practised the rhythm method of birth control, and for women who breastfed. It is possible that these reduced risks may relate to unmeasured variables of life-style.

Future trends in cervical cancer

The identification of the close association of certain types of human papillomavirus with the development of cervical cancer should lead to an extensive revision of appropriate health policies. Having taken into account the drawbacks inherent in the existing data (stemming from the use of varying nomenclature, diagnostic methods and reliability, registration and screening practices) it is possible to conclude that the incidence of HPV infections, all premalignant and malignant stages of cervical cancer are, or will soon be, increasing in several countries. This rate of increase is fastest for the younger age groups and is despite the introduction of various forms of screening. These trends therefore indicate an urgent need to adopt policies to avert an unnecessary increase in fatalities due to cervical cancer. It is therefore recommended to: (1) establish a routine diagnostic method which can identify either the type of HPV present or the lesions which are progressing; (2) determine the incidence of HPV infections in the general population; (3) disseminate to medical personnel, teachers, and other members of society existing knowledge concerning the dangers associated with this virus and relevant to preventing its further spread; (4) introduce an effective population screening campaign for all sexually active women, preferably involving a yearly examination at a colposcopy clinic; (5) intensify basic and applied HPV research, especially that which could lead to a deeper understanding of viral transmission and infection, identification of cofactors which promote cervical lesion progression, or to the production of a vaccine.

Risk factors for adenocarcinoma of the cervix: a case-control study

To assess risk factors for cervical adenocarcinoma data were collected in a case-control study of 39 cases and 409 controls conducted in the greater Milan area. Questions were asked about personal characteristics and habits, gynaecologic and obstetric data, history of lifetime use of oral contraceptives and other female hormones, and general indicators of sexual habits (age at first intercourse and total number of sexual partners). The relative risk of cervical adenocarcinoma increased with number of births and abortions, early age at first birth and early age at first intercourse. These estimates did not materially change after adjustment for the potential reciprocal confounding effect. Further, there was a positive association with overweight, but an apparent association with lower education was not significant. No relationship emerged with oral contraceptive use. Thus, despite the similarities with the epidemiology of squamous cell cancer, reproductive patterns and other factors related to the risk of endometrial cancer (i.e., overweight) seem to play an important role in the risk of adenocarcinoma of cervix uteri.

The biology and significance of human papillomavirus infections in the genital tract

A variety of human papillomavirus (HPV) types infect the anogenital mucosa, giving rise to lesions that differ in clinical appearance, histology, and risk of malignant progression. Certain high-risk types (HPVs 16, 18, 31, 33, 35 and 39) have a strong association with high-grade epithelial neoplasia and invasive carcinomas of the anogenital tract. Cancer appears to have a multifactorial etiology, and HPV infection alone is probably insufficient for malignant transformation. The consistent association between HPV infection and anogenital cancers emphasizes, however, that the sexually transmitted papillomaviruses may have a necessary role in carcinogenesis. Hence, there is a prospect that vaccination programs may one day allow public health control of HPV infection, thereby eliminating an important risk factor.

Low prevalence of cervical intraepithelial neoplasia among Egyptian females

Analysis of 4458 patients evaluated by cytology at the Department of Obstetrics and Gynecology, Kasr El-Einy Hospital, Cairo University, during the years 1981 to 1985 revealed that only 1.07% of these women had abnormal cytology. The prevalence rate for cervical intraepithelial neoplasia (CIN) was remarkably low, corresponding to 3.59/1000 for CIN grade I, 2.28/1000 for CIN II, and 1.16/1000 for CIN III. The mean age for CIN was 44.23 years while that for cervical cancer was 54.32. This low prevalence rate of CIN among Egyptian females, together with the late onset of the disease in comparison with other populations, calls for further study of the epidemiologic characteristics of this low-risk community.

Squamous and adenocarcinoma of the uterine cervix: a comparison using routine data

We studied the clinical, demographic and survival characteristics of more than 5,000 women registered with either squamous or adenocarcinoma of the uterine cervix in South Thames Cancer Registry over the period 1968-81. There were similarities with respect to social class, smoking habit, oestrogen/oral contraceptive use and time trends in incidence but differences between the two cancers were found with respect to age distribution, parity, method of detection and survival. Some of the data are of limited value, having been obtained only from case notes, so the results need some caution in their interpretation. However the results are broadly consistent with those of studies performed in other countries on smaller samples. A methodological issue is also raised, viz. the appropriateness of a disease with well-known characteristics as a comparison group. From our results the likely size of various associations can be judged and used in the design of future studies to clarify the epidemiology of cervical adenocarcinoma.

Sexual factors, venereal diseases, and the risk of intraepithelial and invasive cervical neoplasia

The relation between major indicators of sexual habits (age at first intercourse and total number of sexual partners), history of selected venereal diseases, and cervical neoplasia was investigated using data from a case-control study of 206 cases of cervical intraepithelial neoplasia compared with 206 age-matched outpatient controls, and of 327 cases of invasive cancer compared with 327 control subjects in hospital for acute conditions unrelated to any of the established or suspected risk factors for cervical cancer. The relative risks increased with decreasing age at first intercourse and increasing number of sexual partners both for intraepithelial and for invasive cancers. The effects of these two variables were independent, since they were only marginally affected by reciprocal adjustment, or by allowance for several other identified potential distorting factors. The negative association with age at first intercourse was particularly strong in the case of invasive cancers, with risk estimates over five-fold elevated for women reporting their first intercourse before age 18 compared with those aged over 22 years. This relation might be discussed in terms of multistage models of carcinogenesis, which predict that the incidence of epithelial carcinomas is a function of duration of exposure. In fact, when age was allowed for, the relative risks of cervical neoplasia were positively and strongly related with the total duration of the interval between age at diagnosis/interview and age at first intercourse. Clinical histories of several sexually transmitted diseases were positively associated with the risk of intraepithelial neoplasia. In particular, genital warts were reported by nine cases but no control subject. No such association, however, emerged for invasive carcinomas. Thus, the current findings confirm that, although intraepithelial neoplasia and invasive cervical cancer appear to share several important epidemiological features, the specific (infectious) agents implicated in dysplastic lesions probably differ to some extent from those causing invasive cancer.

Epidemiology of uterine cervical cancer

The epidemiology of cervical cancer presents a number of unique challenges, mainly with respect to disentangling correlated factors and to elucidating biological mechanisms. The available evidence suggests a complex multifactorial etiology, although the relative contributions of risk factors and their interactions remain obscure. Infectious agents are strongly suspected, but as yet not conclusively identified. It is also unclear whether there are subgroups of women or periods of life that are most susceptible to the action of infectious agents, and the contribution of the "male factor" needs to be defined. Several epidemiologic leads can be pursued through biochemical and molecular techniques. Most promising is the recent evidence linking certain HPV types to cervical abnormalities, including cancer, and newly developed probes can be incorporated into epidemiologic studies to evaluate an array of risk factors. Endocrine and metabolic assays may be helpful in clarifying the role of exogenous and possibly endogenous hormones. The effects of cigarette smoking may be further evaluated by studying constituents of tobacco smoke and their metabolites in cervical mucus. Finally, the relationship of diet to cervical cancer should be assessed by examining the levels of micronutrients, trace minerals, and other nutritional indices in body tissues and fluids, as well as through interview data. An understanding of cervical cancer etiology will require a better identification of risk factors for precursor lesions as well as factors that enhance their progression to invasive cancer. Through studies that focus on disease stage and time-related events, it should be possible to clarify the multi-stage processes involved in cervical carcinogenesis, and those factors that may inhibit as well as promote transition rates. The protective effects of screening programs deserve further attention, and research into dietary factors may lead in time to nutritional intervention. Investigation by cell type should also be pursued to define the epidemiology of the rarely occurring adenocarcinomas and adenosquamous carcinomas of the cervix. Finally, preventive strategies should be targeted to high-risk populations, especially those of the lower socioeconomic classes and with limited access to medical care. The need for a renewed focus on epidemiology and prevention is emphasized by recent increases in exposure to several postulated risk factors, including sexual promiscuity, oral contraceptives, and smoking.(ABSTRACT TRUNCATED AT 400 WORDS)

The impact of vaginal cytology on cervical cancer risks in Cali, Colombia

The role of vaginal cytology screening in preventing invasive carcinoma of the cervix was investigated in Cali, Colombia. The history of previous participation in screening programs was obtained from 204 patients with invasive carcinoma and from 2 sets of age-matched controls: one from the same health center and one for the same neighborhood of the patient. Our results show that the risk of developing invasive carcinoma is at least 10 times greater in non-screened than in screened women.

Young people's knowledge of the cervical smear test

A sample of three hundred and forty-eight 16 and 17-year-old students (120 boys and 228 girls) on a range of vocational courses were asked a number of questions about the cervical smear test in October 1980. 10% of the boys and 27% of the girls selected "smear" as a word they would associate with cancer, but only 3.3% of the boys and 9.2% of the girls mentioned the cervical smear test as a preventive measure. Approximately a quarter of the students considered cervical cancer to be usually curable with early treatment, and the majority considered it to be rarely curable with late treatment. 38% of the boys and 64% of the girls had heard of the cervical smear test and the doctor, clinic, family planning clinic and hospital were suggested as places where the smear is available. 9% of the girls said they had had a smear test. These results were used as a baseline for the designing of suitable teaching material.

Socio-economic class differences in cancer incidence in Cali, Colombia

Based on census tract information, cancer incidence rates for three socio-economic strata of the city of Cali, Colombia, were calculated. Strong negative associations with socio-economic status were found for cancers of the cervix and stomach. Colon cancer and endocrine-related cancers were positively associated with socio-economic status, while no such association was found for rectal cancer. Contrary to data from developed countries, all smoking-related cancers were positively associated with socio-economic class. The role of socio-economic gradients in developing countries is stressed as a basis for etiological research.

Risk factors for cervical cancer

Despite a long history of research into the epidemiology and biology of cervical carcinoma, a definitive statement about its probable causes still remains elusive. This review recognizes the population based data on high and low risk groups and summarizes the findings from numerous case-control studies which have explored the marital, sexual and reproductive factors associated with cervical cancer. Although vigorously pursued, an increased risk from oral contraceptives has not been convincingly demonstrated. A variety of venereally transmitted organisms appear to be frequent cohabitants with cervical neoplastic cells. Herpesvirus type 2 still remains the prime suspect in the complex pathogenesis of cervical neoplasia. Clinical findings, biological characteristics of the virus, serological studies and interactions of host cells and viral particles continue to stimulate the most intensive investigative efforts.

Case-control study of the husbands of women with dysplasia or carcinoma of the cervix uteri

The husbands of married women with cervical dysplasia, carcinoma-in-situ, or invasive carcinoma of the cervix who, in an earlier study, had claimed to have had no sexual partner other than their husband, were interviewed to determine whether the risk of cervical epithelial abnormalities in the women could be related to their husband's sexual background. Of 322 women previously studied, 57 were eligible for this study and the husbands of 31 of them were interviewed together with the husbands of a control group, matched for age and age at first intercourse. The number of sexual partners reported by the husband was found to be a significant risk factor, with a relative risk of 7.8 for 15 or more partners outside marriage. The relative risk for women who smoked was 7.0, and this was independent of any of the sexual risk factors. The findings for subgroups of women with invasive carcinoma and with dysplasia or carcinoma-in-situ were similar. The data strongly support the view that an infectious agent is involved in the aetiology of cancer of the cervix and suggest that smoking may have an independent carcinogenic action.