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World Cancer Report (WCR)

The first World Cancer Report, published in 2003, provided a concise assessment of current knowledge about cancer, specifically including the distribution of cancer worldwide, and understanding about the causation of cancer in particular communities or, if applicable, in all communities affected by a particular type of cancer (lung cancer, liver cancer, etc.). Also addressed were research findings indicating how cancer may be prevented.

Publication of the first three World Cancer Reports, in 2003, 2008, and 2014, was based on assessments by scientists with outstanding reputations in their respective fields. Such mobilization of international expertise was based on the unique standing of the International Agency for Research on Cancer (IARC). For more than half a century, IARC has provided a basis on which scientists worldwide could strive for a common perspective of agents that cause cancer (through the IARC Monographs), of the pathology and genetics of different cancer types (through the WHO Classification of Tumours), and of how the incidence of cancer may be reduced (through the IARC Handbooks of Cancer Prevention). IARC has also been the means by which the global distribution of cancer has been determined (through the Cancer Incidence in Five Continents series and GLOBOCAN).

Previous World Cancer Reports have covered all such areas of knowledge by engaging hundreds of scientists from many countries to provide their expertise and perspectives. The challenge, but also the strength, of World Cancer Report is that many areas of research must be addressed. Typically, there are more than 50 chapters in World Cancer Report. For the entire volume to be of manageable length, concise presentations are necessary. For it to be accessible, the science needs to be accompanied by informative illustrations. As a result, in addition to being of benefit to cancer researchers seeking to update their knowledge, World Cancer Report provides comprehensive insight to health professionals and policy-makers whose responsibilities extend over very broad areas.

The next World Cancer Report takes inspiration from the international conference “Global Cancer: Occurrence, Causes, and Avenues to Prevention”, held in Lyon in June 2016 to mark the 50th anniversary of the establishment of IARC. At that conference, investigators were united in recognizing that about half of all cancers could be avoided if current knowledge was adequately translated into preventive interventions. The conference was an overwhelming success, and this level of interest was one of the main reasons to orient the next World Cancer Report in a way that will galvanize cancer prevention research in the coming years.

World Cancer Report is a multidisciplinary publication. Thus, in addressing cancer research for cancer prevention, fields of investigation include descriptive epidemiology (the distribution of disease, and specifically cancer, within particular populations), etiology (e.g. metabolism and nutrition, chemicals, infections, radiation, and genetic), cellular and molecular biology, toxicology and pathology, behavioural and social sciences, public health, biostatistics, and informatics.

World Cancer Report is intended to inform cancer researchers about activity in disciplines beyond their own fields of expertise. Communication of information about cancer to health professionals and policy-makers is also a specific goal. To these ends, World Cancer Report is a professional publication which seeks to remove barriers to communication. The use of technical jargon and associated acronyms is avoided as far as possible.

A feature of World Cancer Report, which distinguishes it from many books and related publications about cancer, is its high illustrative content. When possible, cancer distribution, its cause and prevention, and its biological character will be illustrated through diagrams and photographs.

World Cancer Report outlines the impact of cancer on the worldwide community. For example, when describing the causes of cancer, internal air pollution by wood-fired stoves is documented together with air pollution from vehicle exhausts and petrochemical plant emissions. Both tobacco smoking and obesity are common to many countries, but research provides differing insights depending on, for example, local characteristics and social situations.

World Cancer Report is not primarily concerned with the clinical care of people diagnosed with cancer, including the identification and provision of optimal treatment. For information on this matter, please refer to your national cancer society or organization.

World Cancer Report is an IARC publication. The co-editors are IARC Director Dr Christopher P. Wild, IARC Director-Elect Dr Elisabete Weiderpass, and Dr Bernard W. Stewart of the University of New South Wales, Sydney, Australia. The co-editors have determined that the new World Cancer Report will have a specific focus on cancer prevention and the research that underpins prevention.

The previous World Cancer Report was among a spectrum of authoritative publications documenting that the number of cases and the number of deaths from cancer worldwide will progressively rise over the coming decades. In particular as a proportion of national populations, this rise will increasingly be most marked in low-income countries. Dr Wild has highlighted cancer prevention as the option that may best address the increasing cancer burden, by concluding, “We can′t treat our way out of the cancer problem.”

Cancer research for cancer prevention rests on the foundation of knowledge about the extent of the cancer burden for the world′s population as a whole, and then with reference to the incidence of cancer in different regions and countries. The reason why particular tumour types are the major issues in some countries or communities and not in others reflects, to a large extent, the differing causes of cancer and the fact that some cancer (sporadic cancer) occurs without any discernable relationship with causal agents.

Individuals differ in both the extent of their exposure to carcinogens (cancer-causing agents) and their response to such agents. The scope of biological processes that influence cancer development is broad and is basic to influencing just how much cancer of what particular type occurs in a country or region. Increasingly, in common with all aspects of medical research, biological processes influencing cancer development are being analysed and understood with reference to molecular mechanisms, and in particular with reference to genetic information, sometimes referred to as genomics.

Biological processes are far from the only factors that affect cancer development in different communities. Differences in behaviour and differences in social circumstances, often correlated with racial, class, or community-based inequalities, are increasingly researched as critical to the design and efficacy of cancer prevention initiatives. This aspect of cancer research will also be addressed in the new World Cancer Report.

Cancer prevention is achievable, as indicated by downturns, in some countries and communities, in the amount of cancer attributable to tobacco or sun exposure and, in cases of cancer caused by infectious agents, as achieved by vaccination. Other cancers, including cervical, breast, and colorectal cancer, have been reduced in incidence by earlier detection and improved access to treatment as a consequence of national screening programmes. Integrating all such research for optimal and concise presentation will be the primary responsibility of the editors of the next World Cancer Report.

PDF versions of the 2003, 2008, and 2014 World Cancer Reports are available free online.

The new World Cancer Report will have six sections, each containing a number of chapters. An overview of each section is provided here.

Section 1: The global cancer burden

The impact of cancer on the world community is most immediately clear from the number of new cases and mortality. Information currently available presents cancer occurrence in relation to a broad perspective on disease prevention. Beyond this, data from cancer registries in almost all countries enable changes over time (trends) in particular tumour types to be documented. Once recognized, changes in cancer incidence can often be attributed to patterns of human development, and such relationships in turn provide clear opportunities for cancer prevention.

Section 2: Causes of cancer and hazardous circumstances

The fact that a proportion of most tumour types are caused by particular chemicals, radiation, or biological organisms offers, in most instances, an opportunity for cancer prevention. Some causes of cancer have been known for many decades, although exploitation of this knowledge to prevent cancer has rarely been optimal, particularly from a global perspective. Research findings on cancer causation encompass new insights for both well-recognized carcinogens and those cancer-causing agents that have been recently described. A daunting aspect of research is the extent to which carcinogen exposure – and a consequential burden of disease – that has been controlled in one country or community then emerges in another, even to a greater extent.

Section 3: Biological processes in cancer development

Exposure to a particular carcinogen – or, more commonly, multiple circumstances of exposure – accounts for a proportion of human cancers, acting through different biological pathways at a cellular and molecular level. However, not all people known to be at risk after carcinogen exposure develop cancer. Independently, some people are at greater than average risk of developing cancer because of cancer in earlier generations, but not all members of affected families are afflicted. Finally, cancer may be diagnosed in people not known to have been exposed to relevant carcinogens or whose family has no relevant history. These various scenarios can be explained to varying degrees by biological processes that affect some or all tissues; some of these processes may themselves be the result of environmental or lifestyle exposures. Certain of these processes are described in this section, with particular reference to how available knowledge might be used for prevention.

Section 4: Inequalities affecting cancer prevention

Inequalities, specifically as determined by educational attainment and limitations on circumstances, including nutrition and housing determined by financial income, may perturb the efficacy of virtually all initiatives calculated to reduce the burden of cancer. Relevant factors may be particular to certain countries or regions. Means for investigating such associations, and the manner in which adverse outcomes may be minimized, have improved in recent times. Typically, data are available on variations within a particular country, and certain such data are described in this section.

Section 5: Preventing particular tumour types

The truism that cancer is not a single disease but a multiplicity of different diseases is as valid for cancer prevention as it is for clinical management. Broad understandings about cancer causation, development, detection, and avenues to prevention must be qualified to the extent that no specific list of characteristics (e.g. tumour subtypes) and interventions (e.g. methods of early detection) can be applied with equal relevance to all tumour types. Thus, for example, exogenous causes of prostate cancer are not evident; for now, prevention must focus on sporadic disease or detection of precancerous lesions. For many cancers, there are no recognized screening methods applicable to the whole population. However, success with any research undertaking or preventive measure with one tumour type indicates a means to approach the same challenge for other types.

Section 6: The basis for, and outcomes from, prevention strategies

The burden of death from the multiple different tumour types can be reduced in all communities and countries. The incidence of cancer can be reduced by decreasing or eliminating exposure to carcinogens in multiple contexts. Success in reducing smoking-related cancers in some countries indicates a range of measures that may be researched for efficacy in other situations. Changing behaviour related to nutrition, exercise, and weight gain is being actively researched. Vaccination is effective in relation to some cancers caused by infectious agents. Deaths from sporadic cancer may be reduced through chemoprevention and diagnosis of early disease through screening and emerging molecular methods of early diagnosis. Increased risk of cancer may be indicated by family history and addressed by monitoring affected individuals. The extent to which the options summarized here are realized across national boundaries warrants continuing research.