D. Maxwell Parkin

Estimating the world cancer burden : GLOBOCAN 2000

Describing the distribution of disease between different populations and over time has been ahighly successfu l way of devising hypothese s about causation and for quantifying the potential for preventive activities.1 Statistical data are also essentia l componentsof diseasesurveillanceprograms. Theseplay acritical role in the developmen t and implementation of health policy, through identification of health problems, decisions on priorities for preventive and curative programs and evaluation of outcomes of programs of prevention, early detection/screenin g and treatment in relation to resource inputs. Over the last 12 years, aseries of estimates of the global burden of cancer have been published in the International Journal of Cancer. 2–6 The methods have evolved and been refined, but basically they rely upon the best availabl e data on cancer incidence and/or mortality at country level to build up theglobal picture. The results are more or less accurat e for different countries, depending on the extent and accuracy of locally availabl e data. This “databased” approach is rather different from themodeling method used in other estimates. 7–10 Essentially, these use sets of regression models, which predict cause-specifi c mortality rates of different populations from the correspondin g all-cause mortality.11 The constant s of the regression equations derive from dataset s with different overal mortality rates (often including historic data from wester n countries) . Cancer deaths are then subdivided into the different cancer types, according to the best availabl e information on relative frequencies. GLOBOCAN 2000 updates thepreviousl y published data-based global estimates of incidence, mortality and prevalence to the year 2000.12

Global cancer statistics in the year 2000

Estimation of the burden of cancer in terms of incidence, mortality, and prevalence is a first step to appreciating appropriate control measures in a global context. The latest results of such an exercise, based on the most recent available international data, show that there were 10 million new cases, 6 million deaths, and 22 million people living with cancer in 2000. The most common cancers in terms of new cases were lung (1.2 million), breast (1.05 million), colorectal (945,000), stomach (876,000), and liver (564,000). The profile varies greatly in different populations, and the evidence suggests that this variation is mainly a consequence of different lifestyle and environmental factors, which should be amenable to preventive interventions. World population growth and ageing imply a progressive increase in the cancer burden--15 million new cases and 10 million new deaths are expected in 2020, even if current rates remain unchanged.

Estimates of the worldwide incidence of 25 major cancers in 1990.

The annual incidence rates (crude and age‐standardized) and numbers of new cases of 25 different cancers have been estimated for the year 1990 in 23 areas of the world. The total number of new cancer cases (excluding non‐melanoma skin cancer) was 8.1 million, just over half of which occur in the developing countries. The most common cancer in the world today is lung cancer, accounting for 18% of cancers of men worldwide, and 21% of cancers in men in the developed countries. Stomach cancer is second in frequency (almost 10% of all new cancers) and breast cancer, by far the most common cancer among women (21% of the total), is third. There are large differences in the relative frequency of different cancers by world area. The major cancers of developed countries (other than the 3 already named) are cancers of the colon‐rectum and prostate, and in developing countries, cancers of the cervix uteri and esophagus. The implications of these patterns for cancer control, and specifically prevention, are discussed. Tobacco smoking and chewing are almost certainly the major preventable causes of cancer today.Int. J. Cancer 80:827–841, 1999.

Estimates of the worldwide mortality from 25 cancers in 1990

We present here worldwide estimates of annual mortality from all cancers and for 25 specific cancer sites around 1990. Crude and age‐standardised mortality rates and numbers of deaths were computed for 23 geographical areas. Of the estimated 5.2 million deaths from cancer (excluding non‐melanoma skin cancer), 55% (2.8 million) occurred in developing countries. The sex ratio is 1.33 (M:F), greater than that of incidence (1.13) due to the more favourable prognosis of cancer in women. Lung cancer is still the most common cause of death from cancer worldwide with over 900,000 deaths per year, followed by gastric cancer with over 600,000 deaths and colorectal and liver cancers accounting for at least 400,000 deaths each. In men, deaths from liver cancer exceed those due to colo‐rectal cancer by 38%. Over 300,000 deaths of women are attributed to breast cancer, which remains the leading cause of death from cancer in women, followed by cancers of the stomach and lung with 230,000 annual deaths each. In men, the risk of dying from cancer is highest in eastern Europe, with an age‐standardised rate for all sites of 205 deaths per 100,000 population. Mortality rates in all other developed regions are around 180. The only developing area with an overall rate of the same magnitude as that in developed countries is southern Africa. All of eastern Asia, including China, has mortality rates above the world average, as do all developed countries. The region of highest risk among women is northern Europe (age‐standardised rate = 125.4), followed by North America, southern Africa and tropical South America. Only south‐central and western Asia (Indian subcontinent, central Asia and the middle‐eastern countries) and Northern Africa are well below the world average of 90 deaths per 100,000 population annually. Our results indicate the potential impact of preventive practices. It is estimated that 20% of all cancer deaths (1 million) could be prevented by eliminating tobacco smoking. Infectious agents account for a further 16% of deaths. Int. J. Cancer 83:18–29, 1999.

The changing global patterns of female breast cancer incidence and mortality

One in ten of all new cancers diagnosed worldwide each year is a cancer of the female breast, and it is the most common cancer in women in both developing and developed areas. It is also the principal cause of death from cancer among women globally. We review the descriptive epidemiology of the disease, focusing on some of the key elements of the geographical and temporal variations in incidence and mortality in each world region. The observations are discussed in the context of the numerous aetiological factors, as well as the impact of screening and advances in treatment and disease management in high-resource settings.

Use of statistics to assess the global burden of breast cancer.

Abstract:  A variety of statistics are used to quantify the burden (occurrence and outcome) of cancer generally and of breast cancer specifically. When undertaking any cancer control program, understanding these statistics, their source, and their quality is important for assessing the current situation, allocating resources to different control strategies, and evaluating progress. Two core statistics are the cancer incidence rate and the cancer mortality rate, which provide estimates of the average risk of acquiring and of dying from the disease, respectively. About 16% of the worlds population is covered by registration systems that produce cancer incidence statistics, while mortality data are available for about 29%. Breast cancer incidence and mortality vary considerably by world region. In general, the incidence is high (greater than 80 per 100,000) in developed regions of the world and low (less than 30 per 100,000), though increasing, in developing regions; the range of mortality rates is much less (approximately 6–23 per 100,000) because of the more favorable survival of breast cancer in (high‐incidence) developed regions. The incidence of breast cancer is increasing almost everywhere. This unfavorable trend is due in part to increases in risk factors (decreased childbearing and breast‐feeding, increased exogenous hormone exposure, and detrimental dietary and lifestyle changes, including obesity and less physical activity). On the other hand, mortality is now decreasing in many high‐risk countries due to a combination of intensified early detection efforts and the introduction of mammographic screening, resulting in the diagnosis of more small, early stage tumors, and advances in treatment.

Time trends incidence of both major histologic types of esophageal carcinomas in selected countries, 1973–1995

The purpose of our study was to examine the incidence patterns of 2 major histologic types of esophageal cancer, in selected countries world‐wide and to identify components of birth cohort, period and age as determinants of observed time trends using regression modeling. The roles of temporal changes in specification of histology of tumors and of classification of cancers at the gastroesophageal junction as esophageal or gastric in origin were taken into consideration. In all, 56,426 esophageal cancer cases were included. The results indicate that the incidence rate of squamous cell carcinoma of the esophagus has been relatively stable in most of the countries analyzed, although increasing trends were observed in Denmark and the Netherlands (Eindhoven) among men and in Canada, Scotland and Switzerland among women. There was a significant increase in the incidence of esophageal adenocarcinomas in both sexes in the United States (among whites and blacks), Canada and South Australia and in 6 European countries (Scotland, Denmark, Iceland, Finland, Sweden and Norway). In France the increase was limited to men and in Switzerland the increase was observed only in women. Modeling was unable to distinguish which trends were the results of changes in risk between generations (as cohort effects), or changes in all age groups simultaneously (as a period effect).

Global burden of cancer in 2008: a systematic analysis of disability-adjusted life-years in 12 world regions

BACKGROUND Country comparisons that consider the effect of fatal and non-fatal disease outcomes are needed for health-care planning. We calculated disability-adjusted life-years (DALYs) to estimate the global burden of cancer in 2008. METHODS We used population-based data, mostly from cancer registries, for incidence, mortality, life expectancy, disease duration, and age at onset and death, alongside proportions of patients who were treated and living with sequelae or regarded as cured, to calculate years of life lost (YLLs) and years lived with disability (YLDs). We used YLLs and YLDs to derive DALYs for 27 sites of cancers in 184 countries in 12 world regions. Estimates were grouped into four categories based on a countrys human development index (HDI). We applied zero discounting and uniform age weighting, and age-standardised rates to enable cross-country and regional comparisons. FINDINGS Worldwide, an estimated 169·3 million years of healthy life were lost because of cancer in 2008. Colorectal, lung, breast, and prostate cancers were the main contributors to total DALYs in most world regions and caused 18-50% of the total cancer burden. We estimated an additional burden of 25% from infection-related cancers (liver, stomach, and cervical) in sub-Saharan Africa, and 27% in eastern Asia. We noted substantial global differences in the cancer profile of DALYs by country and region; however, YLLs were the most important component of DALYs in all countries and for all cancers, and contributed to more than 90% of the total burden. Nonetheless, low-resource settings had consistently higher YLLs (as a proportion of total DALYs) than did high-resource settings. INTERPRETATION Age-adjusted DALYs lost from cancer are substantial, irrespective of world region. The consistently larger proportions of YLLs in low HDI than in high HDI countries indicate substantial inequalities in prognosis after diagnosis, related to degree of human development. Therefore, radical improvement in cancer care is needed in low-resource countries. FUNDING Dutch Scientific Society, Erasmus University Rotterdam, and International Agency for research on Cancer.

International trends in the incidence of cervical cancer: I. Adenocarcinoma and adenosquamous cell carcinomas.

Time trends in the incidence of cervical adenocarcinoma and adenosquamous cell carcinomas during the period 1973–1991 were examined using data provided by 60 population‐based cancer registries from 32 defined populations in 25 countries. Three components of the incidence trend were studied: age, calendar period of diagnosis and birth cohort. Cumulative incidence rates per 1,000 for 2 groups with age ranges 25–49 and 50–74 years were calculated from the model that best described the incidence data. There was a significant increase in the cumulative incidence of cervical adenocarcinomas in women born in the mid‐1930s and in successive cohorts thereafter in some populations in the United States (whites and Hispanic women), Australia, New Zealand (non‐Maori), England, Scotland, Denmark, Slovenia, Slovakia and Japan (Osaka) and among Chinese women in Singapore, with a general decline in the incidence in women born in earlier periods. In Sweden and Slovenia there is a suggestion of an increasing trend in both age groups. A decrease in incidence in both age groups was apparent in Finland, France and Italy. There were no changes in incidence in 24 registries covering other European, Asian and black populations in the United States. Part of the increase may be attributable to an increasing prevalence of human papillomavirus infection, and part to improvements in screening. Int. J. Cancer 75:536–545, 1998.© 1998 Wiley‐Liss, Inc.

The global burden of urinary bladder cancer

Statistics on the incidence of bladder cancer are particularly hard to interpret, because of changing classification, variations in counting of multiple cancers in the same individual and, most importantly, the variable inclusion of non-invasive cancers in different data sets. Mortality statistics are almost certainly more comparable, but as indirect estimators of disease risk, require some cautious interpretation, because of differing survival between populations, and over time. Cancer of the bladder is estimated to be the ninth most common cause of cancer worldwide (357000 cases in 2002) and the 13th most numerous cause of death from cancer (145000 deaths). Rates in males are three to four times those in females. Incidence rates are high in many southern and eastern European countries, in parts of Africa and the Middle East, and in North America. The highest estimated mortality is in Egypt, where rates are more than three times greater than the highest rates in Europe and eight times those in the USA. In the USA, the incidence in whites is higher than in blacks. In general, in Western countries, incidence rates have been rising, but the increase has slowed or stopped in many. Mortality rates are, for the most part, decreasing. Trends are more variable in developing countries. To some extent, the geography and time trends are related to prevalence of known risk factors, especially exposure to tobacco (responsible for almost one-third of bladder cancer deaths) and, in some specific areas, schistosomiasis.