Modelling the impact of population-based cytologic screening on cervical cancer incidence and mortality in Hong Kong: an age--period--cohort approach

Trends in cervical cancer mortality in China from 1989 to 2018: an age-period-cohort study and Joinpoint analysis

Background

Worldwide, cervical cancer is the second-most-common malignancy of the female reproductive system. Due to its large population, China accounted for 11.9% of cervical cancer deaths, and 12.3% of global cervical cancer DALYs in 2017. In 2009, China launched a nationwide screening program, yet mortality from cervical cancer has shown an upward trend in recent years. The aim of this study was to explore factors affecting cervical cancer mortality rates in China, and contribute to their future reduction.

Methods

In this descriptive study, a Joinpoint regression analysis and age-period-cohort (APC) model based on the intrinsic estimator (IE) algorithm were utilized. Data from the period 1989–2018 were extracted from the International Agency for Research on Cancer (IARC) Database of WHO (1989–2000) and China Health Statistical Yearbook database (2002–2018).

Results

Our study found mortality from cervical cancer to have initially declined, but increase thereafter over the entire observation period in both rural and urban China. The influence of age, period and cohort effect on the mortality rate had statistical significance. The effect of age increased with years, becoming a contributing factor in women aged over 45 years countrywide. Conversely, the cohort effect became a protective factor for women born after 1938 in urban areas, and for women born after 1958 in rural areas. The period effect was relatively less impactful.

Conclusions

The study indicates that organized cervical screening projects facilitated the identification of potential patients, or patients with comorbidities. Correspondingly, mortality was found to increase with incidence, particularly among elderly women, indicating that newly diagnosed patients were at an advanced stage of cervical cancer, or were not receiving appropriate treatment. Therefore, the coverage of cervical cancer screening should be improved, and women’s health awareness promoted. Early diagnosis and treatment is critical to reduce the disease burden and improve outcomes.

Comparison of Secular Trends in Cervical Cancer Mortality in China and the United States: An Age-Period-Cohort Analysis

Background: As one of the most common cancers in the female population, cervical cancer has ranked as the second most incident gynecological cancer in recent years, trailing only breast cancer. We aimed to assess and compare the secular trends in cervical cancer mortality in China and the United States and analyze the independent effects of chronological age, time period and birth cohort using age-period-cohort (APC) analysis. Methods: We performed an age-period-cohort analysis using the intrinsic estimator method to estimate the independent effects of age, time period, and birth cohort on cervical cancer mortality. We collected mortality data for China and the United States from the WHO Mortality Database and China Health Statistical Yearbook database. Results: We examined the general trends in cervical mortality rates in China and the United States during the periods 1988-2012 and 1953-2012, respectively. The age-standardized mortality rates (ASMRs) for cervical cancer in urban China, rural China and the U.S. showed a general decreasing trend during the observation period, except for urban China, which experienced a significant increase beginning in 2002. The mortality rates for cervical cancer in the three areas showed a general increasing trend with age, regardless of the period effect. Period effects declined steadily in both rural China (from 0.19 to -0.26) and the U.S. (from -0.20 to -0.43); however, a slight increasing trend was identified (from -0.25 to 0.33) in urban China, which indicated that the risk of mortality increased with time. Cohort effects peaked in the cohort born in 1911-1915 in both rural China and urban China, declined consistently in the cohort born before 1950, and then decreased again in the cohort born after 1976-1980. The cohort effect in the U.S. peaked in the birth cohort born in 1876-1880, then leveled off and slightly decreased in younger generations. Conclusions: Our study showed that in general, cervical cancer mortality rates increased with age and decreased with birth cohort in the U.S., while the risk of mortality was highest in the cohort born during 1946-1975 in urban China. Additionally, the risk of mortality consistently increased with age in women younger than 64 years old in urban and rural China and began to decline in older groups. Although the age and cohort effects were relatively strong, the period effect may be the key factor affecting cervical cancer mortality trends, mainly reflecting the immediate effects of effective treatment and the implementation of screening.

Disseminating a cervical cancer screening program through primary physicians in Hong Kong: a qualitative study

BACKGROUND

Organized screening programs are more effective and equitable than opportunistic screening, yet governments face challenges to implement evidence-based programs. The objective of this study was to identify reasons for low levels of adoption among primary care physicians of a government sponsored Cervical Screening Program (CSP).

METHODS

We conducted in-depth interviews with a snowball sample of primary care private and public primary care physicians in Hong Kong. Rogers' theory of diffusion of innovation was used to understand the factors that influenced the physicians' practice decisions.

RESULTS

Our study found that Hong Kong physicians made the decision to encourage cervical screening and to participate in the CSP based primarily upon their clinical and business practice needs rather than upon the scientific evidence. The low rates of adoption of the CSP can be attributed to the physicians' perceptions that the program's complexity and incompatibility exceeded its relative advantages. Furthermore, women's knowledge, attitudes and practices, identified as barriers by physicians, were also barriers to physicians adopting the CSP.

CONCLUSIONS

In both private and public health care systems, screening programs that rely on physicians must align program incentives with the physicians' motivators or pursue additional demand creation policies to achieve objectives.

Cancer mortality-to-incidence ratios in Georgia: describing racial cancer disparities and potential geographic determinants

BACKGROUND

The objective of this study was to evaluate racial cancer disparities in Georgia by calculating and comparing mortality-to-incidence ratios (MIRs) by health district and in relation to geographic factors.

METHODS

Data sources included cancer incidence (Georgia Comprehensive Cancer Registry), cancer mortality (Georgia Vital Records), and health factor (County Health Rankings) data. Age-adjusted incidence and mortality rates were calculated by cancer site (all sites combined, lung, colorectal, prostate, breast, oral, and cervical) for 2003-2007. MIRs and 95% confidence intervals were calculated overall and by district for each cancer site, race, and sex. MIRs were mapped by district and compared with geographic health factors.

RESULTS

In total, 186,419 incident cases and 71,533 deaths were identified. Blacks had higher MIRs than whites for every cancer site evaluated, and especially large differentials were observed for prostate, cervical, and oral cancer in men. Large geographic disparities were detected, with larger MIRs, chiefly among blacks, in Georgia compared with national data. The highest MIRs were detected in west and east central Georgia, and the lowest MIRs were detected in and around Atlanta. Districts with better health behavior, clinical care, and social/economic factors had lower MIRs, especially among whites.

CONCLUSIONS

More fatal cancers, particularly prostate, cervical, and oral cancer in men were detected among blacks, especially in central Georgia, where health behavior and social/economic factors were worse. MIRs are an efficient indicator of survival and provide insight into racial cancer disparities. Additional examination of geographic determinants of cancer fatality in Georgia as indicated by MIRs is warranted.

Age-period-cohort models in cancer surveillance research: ready for prime time?

Standard descriptive methods for the analysis of cancer surveillance data include canonical plots based on the lexis diagram, directly age-standardized rates (ASR), estimated annual percentage change (EAPC), and joinpoint regression. The age-period-cohort (APC) model has been used less often. Here, we argue that it merits much broader use. First, we describe close connections between estimable functions of the model parameters and standard quantities such as the ASR, EAPC, and joinpoints. Estimable functions have the added value of being fully adjusted for period and cohort effects, and generally more precise. Second, the APC model provides the descriptive epidemiologist with powerful new tools, including rigorous statistical methods for comparative analyses, and the ability to project the future burden of cancer. We illustrate these principles by using invasive female breast cancer incidence in the United States, but these concepts apply equally well to other cancer sites for incidence or mortality.

Mapping cancer mortality-to-incidence ratios to illustrate racial and sex disparities in a high-risk population

BACKGROUND

Comparisons of incidence and mortality rates are the metrics used most commonly to define cancer-related racial disparities. In the US, and particularly in South Carolina, these largely disfavor African Americans (AAs). Computed from readily available data sources, the mortality-to-incidence rate ratio (MIR) provides a population-based indicator of survival.

METHODS

South Carolina Central Cancer Registry incidence data and Vital Registry death data were used to construct MIRs. ArcGIS 9.2 mapping software was used to map cancer MIRs by sex and race for 8 Health Regions within South Carolina for all cancers combined and for breast, cervical, colorectal, lung, oral, and prostate cancers.

RESULTS

Racial differences in cancer MIRs were observed for both sexes for all cancers combined and for most individual sites. The largest racial differences were observed for female breast, prostate, and oral cancers, and AAs had MIRs nearly twice those of European Americans (EAs).

CONCLUSIONS

Comparing and mapping race- and sex-specific cancer MIRs provides a powerful way to observe the scope of the cancer problem. By using these methods, in the current study, AAs had much higher cancer MIRs compared with EAs for most cancer sites in nearly all regions of South Carolina. Future work must be directed at explaining and addressing the underlying differences in cancer outcomes by region and race. MIR mapping allows for pinpointing areas where future research has the greatest likelihood of identifying the causes of large, persistent, cancer-related disparities. Other regions with access to high-quality data may find it useful to compare MIRs and conduct MIR mapping.

Who receives, benefits from and is harmed by cervical and breast cancer screening among Hong Kong Chinese?

BACKGROUND

To estimate the proportion of and characterize women who had received cervical and breast screening and to quantify the associated preventable burden of disease and potential iatrogenic harm.

METHODS

A total of 3484 Hong Kong Chinese women were interviewed in person. Screening prevalence and associated predictors, disability-adjusted life-years (DALYs), the numbers of false-positive tests and the resultant confirmatory procedures and related complications were estimated.

RESULTS

A total of 6.2% of women (>or=18) reported regular pap but no mammography or clinical breast examination (CBE) as per local evidence-based guidelines, whereas among women aged >or=40 years, 5.2% reported regular screening by all three modalities and 55.3% had never been screened for either cancer. Women who underwent regular health checkups were consistently the most likely to have been screened, as were younger, married and socially advantaged respondents. Triennial pap screening would save 708 DALYs annually, or 528 more DALYs compared with the status quo. However, this would generate 28,600 repeat smears and 390 colposcopies from false-positive screens. Opportunistic mammographic screening averted 100 DALYs currently, but could have potentially reduced a further 546 with biennial screening. Mass screening mammography (CBE) would lead to 33,700 (20,200) false-positives per year requiring 29,900 (8300) repeat mammograms or ultrasonograms, 6800 (3000) biopsies and 620 (270) biopsy-related complications.

CONCLUSIONS

Screening uptake patterns are suboptimal. By making explicit the possible risks and benefits based on this template, policy makers in developing Asia with a similar female cancer burden may be able to use the information to make evidence-based decisions that are consistent with local circumstances, values and preferences.