Abstract SY26-01: Screening and cancer prevention in underdeveloped environments: A global view
Authors: Cazap Eduardo 
Published: August 2012

Today, cancer accounts for approximately one in every eight deaths globally (1) and more than half of the global cancer burden is found in low- and middle-income countries (2). By 2030, it is projected that more than 26 million incident cancer cases will occur each year - more than double the 12.4 million new cancer cases in 2008 (1). Of these, some 70% will occur in low- and middle-income countries (3). By 2050, it is projected that low-income countries alone will account for up to three-quarters of all cancer deaths (4).

There are several reasons - many of them interrelated - why the long-term burdens associated with cancer and other chronic diseases in developing countries are certain to rise. First, the world's population is projected to exceed 8 billion by 2030, with the sharpest increases projected in low- and middle-income countries (1). A growing population will inevitably lead to an increase in the cancer burden. Secondly, as developing economies grow, national populations become more susceptible to chronic diseases associated with affluence (4,5). In China and Latin America, parts of the world that have experienced notable economic advances in recent decades, annual cancer incidence is increasing (6). Obesity is raising in all income strata in low- and middle-income countries, bringing with it increased risks for cancer, heart disease and other chronic diseases (7). Experts foresee a marked increase in tobacco use in developing countries in coming decades (8) and excessive alcohol intake, another risk factor for many cancers, is a particular problem in many developing regions, including sub-Saharan Africa and Eastern Europe. Thirdly, a rapid ageing of national populations is also forecast, especially as countries continue to experience progress in combating diseases that have resulted in substantial premature death. In China alone, life expectancy has increased by two-thirds in the last 40 years (6). This demographic evolution will inevitably lead to increases in cancer, which is more likely to be diagnosed among older people (9).

Communicable diseases also contribute to the cancer burden in many developing countries. WHO reports that cancers related to seven infectious agents - including hepatitis, human papillomavirus, and blood and liver flukes - together account for 18% of global cancer deaths, and disproportionately impact low- and middle-income countries (8). In some countries, high prevalence of HIV is also driving increases in certain cancers, such as Kaposi's sarcoma, non-Hodgkin lymphoma, and invasive cervical cancer (10).

On average, cancer is diagnosed much later in resource-limited settings than in high-income countries. It is estimated that up to 80% of cancers in low- and middle-income countries may be incurable by the time they are diagnosed (11). Comparative international studies indicate that late diagnosis accounts for a substantial share of sub-optimal cancer outcomes in developing countries (12).

Early diagnosis of cancer is critical to improving medical outcomes, especially in settings where expensive, state-of-the-art interventions may not be available to treat late-stage cancers. To generate population-level improvements in cancer outcomes, screening programs need to achieve high coverage, rely on high quality screening tests, and be linked to timely follow-up care (13).

Ethiopia's efforts to improve breast cancer outcomes offer valuable insights regarding promotion of earlier cancer diagnosis. A recent study found that low levels of cancer awareness and late diagnosis in Ethiopia contribute to suboptimal health outcomes, underscoring the importance of coupling technical initiatives to build diagnostic capacity with public education campaigns to help individuals recognize cancer risks and to motivate them to seek diagnostic screening. The study also highlights the need for careful system planning and streamlining to avoid delays in cancer diagnosis and linkage to care. In Ethiopia - where health service delivery is often fragmented and where many patients first consult traditional healers - cancer patients typically go through three or more care channels before they reach the hospital they need (14).

Other studies suggest that screening for a number of treatable cancers - such as colorectal, cervical, or breast cancer - meets recognized cost-effectiveness criteria in low- and middle-income countries (15). In a number of cases, low-tech, more affordable alternatives exist to expensive, state-of-the-art screening methods routinely used in high-income countries.

Advances in affordable screening options for cervical cancer, for example, include direct visualization of precancerous lesions (either with coloration with acetic acid or with Lugol's iodine), as well as screening for chronic HPV infection (11) For colorectal cancer screening, fecal occult blood tests may be a suitable alternative to more complicated sigmoidoscopy or colonoscopy (16) Especially at the earlier stages of efforts to bring cancer care to developing countries, initial work to expand diagnostic capacity should focus on high-prevalence settings where such initiatives will be most cost-effective. For example, in many developing countries, it appears that urban-dwelling women tend to be at greater risk for breast cancer than women living in rural areas, presumably because of differences in lifestyle and exposure to potential carcinogens (17,18). In light of higher population density in urban areas and their relatively better developed service infrastructure, the epidemiology of breast cancer in such settings strongly suggests that an early focus on scaling up diagnostic services in urban settings will be most cost-effective and have the greatest public health impact.

In 2008 the Union for International Cancer Control (UICC) issued the World Cancer Declaration. The Declaration presented 11 Targets which to be achieved by 2020, including the development and implementation of National Cancer Control Plans, the growth and use of population-based cancer registries, the implementation of policies to reduce the burden of cancer risk factors and the prevention of those cancers which can be prevented, and the enhancement of screening and early detection capabilities. (19)

Recently, in September 2011, the UN High Level Meeting has elevated the global issues related to cancer and NCDs and brought them to the attention of the world's leaders. These major public health threats to every nation can be averted if we take action now. Screening and cancer prevention are a key component in this global strategy. (20)

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15. Brown ML et al. (2006). Health Service Interventions for Cancer Control in Developing Countries, in Disease Control Priorities in Developing Countries (2nd ed.) (Jamison DT et al., eds.). Oxford University Press and World Bank.

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19. Union for International Cancer Control (2008) WCD, Geneva, Switzerland

20. Global Status Report on NCD's2010; WHO

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr SY26-01. doi:1538-7445.AM2012-SY26-01