Incidence Of Invasive Cervical Cancer Research Articles

Relation between the incidence of invasive cervical cancer and the screening interval: is a five year interval too long?

To examine the incidence of invasive cervical cancer per 100,000 women years at risk and relative risk according to screening history among eligible women aged 25-69 in Southampton and South West Hampshire during the three years after completion of the first round of comprehensive screening. There was a significantly higher incidence of invasive cervical cancer in women who had not been screened during the preceding 0.5-5.5 years than in those who had been screened (relative risk (RR) 2.6; 95% confidence interval (CI) 1.6 to 4.3). Among the latter group of women (with interval cancers) there was a significantly higher incidence in those with a long interval of 3.5-5.5 years since their most recent smear than in those with a short interval of 0.5-3.5 years (RR 2.2; 95% CI 1.3 to 3.8). Among women with non-interval cancers, there was a significantly higher incidence among those who had no cytology record than among those who had been screened but were overdue for a smear (RR 3.0; 95% CI 1.2 to 7.3). When screen detected cancers were excluded from the figures the relative risks for all the comparative groups described above were greater, though the 95% confidence limits were wider because the numbers were smaller. The most pronounced difference in incidence was between symptomatic cancers in women with a short screening interval (5.8 per 100,000 women years at risk) and in women with no cytology record (71.3 per 100,000 years at risk). Most cancers were interval cancers (76%) because of the high screening coverage: 89.2% of eligible women aged 25-69 had been screened during the preceding 0.5-5.5 years. The overall incidence per 100000 women years at risk approached that of interval cancers, and was nearer to that observed in the short than the long interval because 74.7% of women had been screened within 3.5 years. The results confirm the effectiveness of screening but suggest that a five year screening interval may be too long, at least during the early rounds of screening.

Geographical distribution of risk factors and incidence of invasive cervical cancer in south east China.

Geographical distribution of risk factors and incidence of invasive cervical cancer in south east China.

Low efficiency of cytologic screening for cancer in situ of the cervix in older women

Cytologic screening for cervical cancer has proven to be beneficial in many countries, although the value of this intervention in women older than 50 years remains controversial. The purpose of this study was to investigate the efficiency of detecting cancer in situ by means of a cytologic smear at different ages, with special emphasis on the benefit of screening in women above the age of 50. We analyzed 466,275 smears taken in an open cohort of 118,890 women in Sweden between 1969 and 1988. The number of cancers in situ detected per 1,000 smears, the detection ratio, was used as an outcome measure in univariate analyses and in multivariate regression models. Cancer in situ was detected in 1,076 women in the study cohort. The detection ratio peaked at ages 30 to 34 and decreased heavily during the next 15 years of age. The efficiency of taking smears at ages above 50 was only 20 per cent (OR, 0.19; 95% CI, 0.14-0.26) of that at ages 30 to 34. These results were not changed when adjusting for time period and time interval since the previous smear. In spite of a high incidence of invasive cervical cancer in older women, the benefit of cytologic screening to detect cancer in situ above the age of 50 is uncertain.

Human papillomavirus-associated malignancies in HIV-positive men and women

Human papillomavirus (HPV) infections of the anogenital tract and HPV-associated anogenital neoplasia are commonly found in HIV-positive men and women. Although there is little evidence suggesting that the incidence of invasive cervical cancer is increased in HIV-positive women, the incidence of invasive anal cancer may be increased in HIV-positive men. Among HIV-positive women, cervical intraepithelial neoplasia progresses more rapidly and recurs more often after primary therapy than in HIV-negative women. HPV infection and HPV-associated disease are often multifocal in HIV-positive women, and they may be found in both the vulva and the anus. Cervical cytology appears to be adequate as a screening tool for cervical intraepithelial neoplasia in HIV-positive women, but the high recurrence rate and multifocal nature of this disease reinforces the need for careful evaluation and follow-up of the entire anogenital tract in these women.

Duration of preclinical cervical cancer and reduction in incidence of invasive cancer following negative pap smears.

An investigation has been made into the differences between estimates for the duration of preclinical cervical cancer resulting from two types of studies. A median duration of 5-10 years was suggested by the observed build-up of incidence of invasive cervical cancer after one or more negative smears. Much longer median durations of more than 15 years have been reported from fitting statistical models to screening data. We developed one of these statistical models and fitted it to clinical incidence and screening data from British Columbia, which resulted in estimated mean durations of 12 years for pre-invasive stages, and 4-5 years for screen-detectable stages. The model is used to predict the build-up of the incidence of invasive cancer after one and after two negative smears. The model predictions appear to correspond closely to the observed incidence trends following negative smears. The apparent contradiction between model estimates and observed data is explained by recognizing that many of the women who have had negative smears will have further Pap smears, resulting in earlier diagnosis of invasive cervical cancers and thus an apparent faster build-up of the incidence. When the impact of further Pap smears is neglected, the data suggest that the risk of invasive cancer following one or more negative smears returns to close to prescreening levels within 6-10 years. This is an overestimation of the risk of clinical invasive cancer. In the case of cessation of screening it will take longer before the incidence of clinical cancer will increase. Where there is continuous screening the screen-detected cancers have a relatively favourable prognosis, thus contributing less to the serious morbidity and mortality risks associated with invasive cancer. This should be taken into account in making comparisons with the prescreening situation.

Invasive cancer of the cervix in women with mild dyskaryosis followed up cytologically.

Mildly dyskaryotic smears are common, and women with such results are often followed up with further cervical smear tests. An important consideration in evaluating this practice would be the annual incidence of invasive cervical cancer. A reanalysis of five previous studies of the cytological follow up of women with mildly abnormal smear test results was undertaken to calculate this incidence. The annual incidence of invasive cancer in these women ranged from 0 to 420 per 100,000 women years. The large studies providing the most precise estimates had annual rates of 143 to 420 per 100,000 women years. This is 16 to 47 times greater than in women aged 15-34 years in England and Wales. The average rate was 208 per 100,000 women years. Women with mild dyskaryosis are at high risk of developing invasive cervical cancer despite cytological follow up. A full appraisal of the costs and benefits of colposcopy in this situation is urgently required.

Cytological screening and management of abnormalities in prevention of cervical cancer: an overview with stochastic modelling.

To develop a mathematical model of the histological changes of precancer and the development of invasive cancer and how these are related to cytological findings. To use this to investigate the effects on incidence of cervical cancer, number of smear tests and colposcopies, of different schedules for cervical screening, and the clinical management policies for dyskaryosis. A stochastic model was developed relating the available data on tissue progression to the cytological findings. Two strategies, A and B, were compared: under A, women with any abnormal smear receive immediate colposcopy and treatment; under B, women with mild or borderline dyskaryosis have repeated smears at six monthly intervals with colposcopy only for persistent abnormalities. The model predicted an incidence of invasive cervical cancer in an unscreened population of women aged over 18 years of 5.9 per 10,000 per year. With 70% coverage and three yearly screening under strategy A, the incidence fell to 2.00 and under B to 2.10. The number of smears required was similar but A required two to three times as many colposcopies as B. Raising the coverage to 90% reduced the incidence to around 1 per 10,000 per year but changing the screening interval, the specificity or sensitivity of cytology had much less effect. The model has been tested under a wide range of possible variations in natural history, specificity and sensitivity of cytology. For low grade smear abnormalities, open colposcopic referral is predicted to reduce invasive cancer only slightly more than repeat cytology, at the expense of much additional colposcopy. Improving cytological coverage is suggested as more effective in reducing invasive cancer than increased use of colposcopy or more frequent screening.

Trends in cervical cancer incidence among young black and white women in metropolitan Detroit.

Although the overall incidence of invasive cervical cancer in the United States has declined over the past several decades, recent studies suggest that rates for both invasive and in situ cervical cancer are rising among younger women. Trends in cervical cancer incidence among females between the ages of 15 and 39 years were evaluated using data from the Metropolitan Detroit Cancer Surveillance System, a population-based registry and founding participant in the SEER Program of the National Cancer Institute. Age-adjusted and age-specific rates for all black and white women in this age group were evaluated as well as rates for married and single women for the period 1973-1991. Incidence trends vary by race and marital status. A nonlinear increasing trend was evident (P < 0.01), for in situ cervical cancer among white women, with rates for single white women exhibiting the largest increase. Rates among black women for in situ cervical cancer exhibited a nonlinear decreasing trend (P < 0.01), with rates for married black women declining by 75%. Among single white women, invasive cervical cancer exhibited an increasing linear trend (P < 0.01), although the number of cases was small. Differences in trends among black and white women may reflect a combination of greater exposure to risk factors associated with cervical carcinoma as well as differential access to diagnostic and treatment services. Appropriate groups should be targeted for educational, screening, and follow-up services.

Incidence of invasive cervical cancer preceded by negative screening in high-risk Alaska Native women.

Alaska Native women experience higher invasive cervical cancer incidence and mortality rates than US whites despite a long-standing cancer screening programme including recommendations for annual Pap smears. To determine the frequency and results of cytological screening preceding their diagnoses, a histological and medical record review was completed for 44 of 46 Alaska Native cases of invasive cervical cancer from a defined population. An interval cancer (no prior dysplasia and a negative screening report within 3 years of diagnosis) was determined for 23 women. Mean number of negative reports during the 3- and 5-year intervals before diagnosis was 1.7 and 2.6 respectively. The age-adjusted incidence rate for all cervical cancer was 24.0/100,000 women/year and for interval cancer with single and multiple negative reports during the 3-year interval before diagnosis it was 11.6, and 9.6 respectively. Sensitivity of a Pap smear to demonstrate dysplasia during the year before diagnosis was 51%. Annual cytological screening of all Alaska Native women with current methods would provide earlier diagnoses for only an additional 15% of cervical cancer cases. Plausible but unproven explanations include rapid progression through precursor stages of neoplasia or random screening errors. Improved or ancillary screening methods appear necessary.

Effect of the Clinical Laboratory Improvement Amendments of 1988 (CLIA '88) on the incidence of invasive cervical cancer.

The Clinical Laboratory Improvement Act of 1988 (CLIA '88) mandates strict, new quality-control measures for laboratories that interpret cervical cytology smears. Proposed regulations include proficiency testing of cytotechnologists and remediation for technologists and laboratories that fail to meet proposed proficiency standards. Proponents of the new regulations argue that these measures will reduce deaths from cervical cancer by reducing the false-negative rate of the Papanicolaou (Pap) test, but opponents argue that the regulations will increase the price of processing Pap tests and thereby reduce access to cervical cancer screening for high-risk, vulnerable populations. To examine these claims the authors used David Eddy's published simulation to model the natural history and detection of cervical neoplasia, and developed a new model to examine the health consequences of diminished access to Pap testing. The authors estimated the false-negative rate of the Pap test and the price elasticity of demand for preventive services on the basis of the published literature, and modeled the entire range of published or quoted predictions about the impact of CLIA '88 on accuracy and price. The results show that, if effects on access are ignored, reducing the false-negative rate from 15% to 5% would prevent 66 invasive cancers per 100,000 average risk women screened. However, under moderate assumptions regarding the effect of price on access, the regulations would prevent only 11 (instead of 66) cancers per 100,000 eligible women. The regulatory effect is very sensitive to the degree of improvement in the false-negative rate and increase in price that the regulations cause. Over the range of assumptions and predictions encountered in the literature and tested in our analysis, the proposed regulations could greatly reduce or greatly increase the incidence of invasive cancer, especially among high-risk and uninsured women. The implementation of the regulations should be delayed until new information regarding the actual false-negative rate of the Pap test allow a more precise estimate of the potential impact on the incidence of cervical cancer.

Screening for cervical cancer in Latin America: a case-control study.

The beneficial effect of cervical cytology in reducing the incidence of invasive cervical cancer is well accepted, but many issues regarding specific patterns of screening remain to be resolved, and preventive programmes need to be adapted to regional characteristics. In a case-control study conducted in Latin America, we investigated cytological screening histories of 759 cases of invasive cervical cancer and 1430 controls, with participation rates of 99% and 96%, respectively. Fifty per cent of the cases and 29% of the controls reported never having been screened. Screening was less common among older, less educated and less parous women; non-users of oral contraceptives and women without histories of venereal diseases. There was also evidence that older women and those with multiple partners had longer intervals between examinations. The relative risk (RR) associated with no prior screening was approximately 3 and was not modified by other risk factors. Women reporting a Pap smear within 24-47 months before interview had the same RR as those examined within 12-23 months. Women tested longer ago had higher risks, but still much lower than women never examined. There was evidence that one examination is associated with less reduction in risk than two, regardless of the interval since last Pap smear. Screening appeared to reduce risk of both squamous cell carcinomas and adenocarcinomas. As expected, cases presenting at advanced stages were less likely to have been screened and reported longer intervals since their last examination. These results support the need to concentrate limited resources in the groups that need screening most, mainly older and less educated women who have never been screened.

Screening for Cervical Cancer

Indirect evidence indicates that cervical cancer screening should reduce the incidence and mortality of invasive cervical cancer by about 90%. In the absence of screening, a 20-year-old average-risk woman has about a 250 in 10,000 chance of developing invasive cervical cancer during the rest of her life, and about a 118 in 10,000 chance of dying from it. Screening at least every 3 years from 20 to 75 years of age will decrease these probabilities by about 215 in 10,000 and 107 in 10,000, respectively, and will increase a 20-year-old woman's life expectancy by about 96 days. The particular age at which screening is begun (for example, 17 or 20 years), the requirement of several initial annual examinations before reducing the frequency, and screening every 1 or 2 years compared with every 3 years improves the effectiveness by less than 5%. Screening is recommended at least every 3 years from about age 20 to about age 65 years.

Recent trends in cervix uteri cancer

Since the prevalence of several risk factors for cervix uteri cancer, such as sexual activity patterns, cigarette smoking, and contraceptive use, has changed over time, the authors analyzed US trends for this cancer during the 1970s to 1980s to search for corresponding variations. Invasive cervical cancer incidence and mortality rates continued to decrease among blacks and whites, although declines are moderating or plateauing among young whites. Carcinoma in situ rates have not changed greatly or have declined, more so among blacks than whites. Excess risks among blacks are less evident among younger than older age groups. Increasing trends were seen only among whites in certain age groups or with certain histologic types. Declining trends in cervical cancer appear related to the widespread use of cervical cytologic screening programs, which have counteracted increases anticipated from changes in risk factor prevalence. Continued surveillance is warranted, however, with special attention to the trends in cervical adenocarcinoma.

Incidence of invasive cervical cancer in the Swiss canton of Vaud, and a note on screening.

Age adjusted incidence rates (World standard) from invasive cervical cancer in the Swiss canton of Vaud decreased from 17.7/100,000 in 1968-70 to 9.9/100,000 in 1983-85. The decline was substantial in younger middle age, but no appreciable trend was observed in women over 70. This is consistent with available interview based information on the pattern of cervical screening in the Swiss population. Although there was no organised screening programme in Switzerland, over 80% of women aged 20-44 and 65% of those aged 45-64 reported one or more screening smears over the previous 3 years, compared to only 22% of women aged 65 or over. In the last calendar period, there was an apparent increase in the incidence of invasive cervical cancer (from 2.5 to 6.1/100,000) in women aged 25-29. Although based on small absolute numbers, this is in agreement with incidence and mortality data from other countries, and may therefore confirm a change in risk factor exposure in younger women.

Oral Contraceptive Use and Malignancies of the Genital Tract

Of 47,000 women followed since 1968, those who had used oral contraceptives (ever-users) had a significantly higher incidence rate of cervical cancer than never-users. After standardisation of rates by age, parity, smoking, social class, number of previously normal cervical smears, and history of sexually transmitted disease, the excess was 41 per 100,000 woman-years for carcinoma-in-situ and 8 per 100,000 woman-years for invasive cervical cancer. Incidence increased with increasing duration of use: the standardised incidence rate for cervical cancer in women who had taken the pill for more than 10 years was four times than in never-users. Ever-users had a lower incidence of other uterine cancers (deficit 5 per 100,000 woman-years); a lower incidence of ovarian cancer was also found (deficit 4 per 100,000), but was not statistically significant. Overall, ever-users had an excess incidence for genital tract cancers 37 per 100,000 woman-years. This excess was mainly from carcinoma-in-situ of the cervix; the excess incidence of invasive cervical cancer was offset by the deficits in other uterine and ovarian cancers. Standardised mortality rates from genital cancer were similar in ever-users and never-users. Of relevance to clinical practice is the substantially different distribution of primary cancer sites: cervical cancer accounted for 75% of the invasive genital cancers and 74% of deaths from genital cancer in ever-users, but only 31% of the invasive cancers and 30% of deaths in never-users.

ORAL CONTRACEPTIVE USE AND MALIGNANCIES OF THE GENITAL TRACT: Results from The Royal College of General Practitioners' Oral Contraception Study

Of 47 000 women followed since 1968, those who had used oral contraceptives (ever-users) had a significantly higher incidence rate of cervical cancer than never-users. After standardisation of rates by age, parity, smoking, social class, number of previously normal cervical smears, and history of sexually transmitted disease, the excess was 41 per 100 000 woman-years for carcinoma-in-situ and 8 per 100 000 woman-years for invasive cervical cancer. Incidence increased with increasing duration of use: the standardised incidence rate for cervical cancer in women who had taken the pill for more than 10 years was four times that in never-users. Ever-users had a lower incidence of other uterine cancers (deficit 5 per 100 000 woman-years); a lower incidence of ovarian cancer was also found (deficit 4 per 100 000), but was not statistically significant. Overall, ever-users had an excess incidence for genital tract cancers of 37 per 100 000 woman-years. This excess was mainly from carcinoma-in-situ of the cervix; the excess incidence of invasive cervical cancer was offset by the deficits in other uterine and ovarian cancers. Standardised mortality rates from genital cancer were similar in ever-users and never-users. Of relevance to clinical practice is the substantially different distribution of primary cancer sites: cervical cancer accounted for 75% of the invasive genital cancers and 74% of deaths from genital cancer in ever-users, but only 31% of the invasive cancers and 30% of deaths in never-users.

A case-control study of the effectiveness of cervical cancer screening in Osaka, Japan.

In the small town of Nose in Osaka, Japan, a population‐based screening program for cervical cancer by Papanicolaou smear has been conducted since 1965. In order to evaluate the effectiveness of screening in terms of the reduction of the mortality and the incidence of invasive cervical cancer, two types of case‐control studies were carried out. In the first study, the case series consisted of all women who died of cervical cancer under 80 years of age at the time of diagnosis in 1965‐1987 (N = 15). For each case, 10 controls were chosen from living residents, matched by year of birth. It showed that the odds ratio (OR) of dying of cervical cancer for screened versus non‐screened women was 0.22 (95%CI = 0.03‐1.95). In the second study, the case series consisted of all women who were diagnosed as having invasive cancer under 80 years of age at the time of diagnosis in the same period (N = 28). For each case, 10 controls were chosen from living residents without invasive cancer, matched by year of birth and according to whether or not they were screened at the year of the diagnosis of the matched case. It showed that the OR of getting invasive cancer for screened versus non‐screened women was 0,41 (95%CI = 0.13‐1.29). From these results, it was estimated that 78% of cervical cancer mortality and 59% of invasive cervical cancer incidence among non‐screened women could be prevented by cervical cancer screening.

Decreasing incidence of invasive cervical cancer in young women

Although the overall incidence of invasive cervical cancer is decreasing, there is concern that the disease might be increasing in younger women. Analysis of data from the Cancer Surveillance System, a population-based cancer registry in western Washington, shows a decreasing incidence of cervical cancer in women of all ages.

The frequency of cervical cancer screening. Comparison of a mathematical model with empirical data.

The results of a mathematical model used to analyze the frequency of the Pap smear are compared with a recently published independent empirical study of data from large screening programs in Europe and North America. The model's predictions of the reduced incidence of invasive cervical cancer achieved with different screening frequencies match the empirical results closely--the predictions were within 1% of the empirical results for screening frequencies ranging from 1 to 10 years. The data indicate that compared with annual screening, screening every 2, 3, 5, and 10 years retains 99%, 97%, 89%, and 69%, respectively, of the effectiveness measured as a reduction in frequency of invasive cancer. The mathematical model underestimated the effectiveness of screening every 3 years, compared with screening every year.

Cervical cancer screening in women aged 65 and over.

Pap smear screening is an accepted method of detecting cervical dysplasia or malignancy, and use of this test has been shown to reduce the incidence of invasive squamous cervical cancer in young and middle aged women. Conflicting recommendations exist concerning the screening of women over the age of 65, and little information is available concerning the results of screening in this population. Elderly women are routinely omitted from screening, as it is generally believed that they usually refuse testing. This paper reports a study attempting to evaluate the feasibility of screening in women over the age of 64 attending a large urban outpatient geriatric clinic. It demonstrates that pap smear screening is acceptable to this population, particularly if performed by the usual primary care provider. It also confirms previous reports that women in this age group have had very little screening in the past, and that screening uncovers a large number of abnormalities. Of note is the high rate of false positive smears in this population.