Breast cancer is the number one cancer in women in both developed and developing countries. In developing countries, the incidence of breast cancer is increasing due to increased life expectancy, expanding urbanization and the adoption of Western lifestyles.
While preventive measures may reduce some risk, such strategies cannot eliminate the majority of breast cancers that develop in low- and middle-income countries, where breast cancer is not diagnosed until a very late stage. Therefore, early detection in order to improve breast cancer outcomes and survival remains the cornerstone of breast cancer control.
The recommended early detection strategy for low- and middle-income countries is to look for early signs and symptoms and to screen with clinical breast examinations in the areas of presentation. Mammography screening is costly and is recommended in countries with good health infrastructure and can afford long-term planning.
Many low- and middle-income countries facing the dual burden of cervical and breast cancer need to implement cost-effective and affordable combined interventions to address these two highly preventable diseases.
The World Health Organization (WHO) promotes breast cancer control in the context of national cancer control planning and in conjunction with the prevention and control of non-communicable diseases. With support from the Susan G. Komen Breast Cancer Foundation, WHO is currently conducting a five-year study of the cost-effectiveness of breast cancer in ten low- and middle-income countries.
The project includes planning costing tools to assess affordability. The results of the project are expected to help provide evidence that can be used to develop appropriate breast cancer policies in less developed countries.
Burden of Breast Cancer
Breast cancer is the most common cancer among women worldwide, accounting for 16% of all women’s cancers. It is estimated that 519,000 women died from breast cancer in 2004. And although breast cancer is considered a disease of developed countries, the majority of breast cancer deaths (69%) occur in developing countries (WHO Global Burden of Disease, 2004).
Globally, incidence rates vary widely, with age-specific incidence rates as high as 99.4 per 100,000 in North America. incidence rates are slightly lower but increasing in Eastern Europe, South America, Southern Africa and Western Asia. The lowest incidence rates are found in most African countries, but breast cancer incidence is also increasing there.
Worldwide, breast cancer survival rates vary widely, from 80% or more in North America, Sweden, and Japan to about 60% in middle-income countries and less than 40% in low-income countries (Coleman et al., 2008). The lower survival rates in less developed countries can be largely explained by the lack of early detection planning, which results in a large proportion of women not seeking care until the disease is advanced, and the lack of appropriate diagnostic and treatment facilities.
High risk factors for breast cancer
Several high-risk factors for breast cancer are well documented. However, specific high-risk factors cannot be identified for the majority of women who develop breast cancer (IARC, 2008; Lacey et al., 2009).
A family history of breast cancer can double or triple the risk. Some mutations, particularly in BRCA1,BRCA2 and p53, produce a high risk of breast cancer. However, these mutations are rare and account for a small percentage of the total breast cancer burden.
Reproductive factors associated with chronic exposure to endogenous estrogens, such as early onset of menarche, delayed menopause, and advanced age at first birth, are several of the most important risk factors for breast cancer. Exogenous hormones also produce a higher risk of breast cancer. Users of oral contraceptives and hormone replacement therapy are at higher risk than non-users. Breastfeeding has a protective effect (IARC, 2008, Lacey et al., 2009).
Danaei et al. calculated the effect of various modifiable risk factors (excluding reproductive factors) on the total burden of breast cancer (Danaei et al., 2005). They concluded that 21% of all breast cancer deaths worldwide could be attributed to alcohol consumption, excess weight and obesity, and lack of physical activity.
This proportion was higher in high-income countries (27%), where the most important factors were excess weight and obesity. In low- and middle-income countries, the proportion of breast cancers attributable to these high-risk factors was 18%, with physical inactivity being the most important determinant (10%).
The role of diet combined with later primiparity, fewer births, and shorter duration of breastfeeding may partially explain the differences in breast cancer incidence between developed and developing countries (Peto, 2001). The increasing adoption of Western lifestyles in low- and middle-income countries is an important determinant of the rising incidence of breast cancer in these countries.
Control of breast cancer
WHO promotes breast cancer control in the context of comprehensive national cancer control planning integrated with non-communicable diseases and other related issues. Comprehensive cancer control involves prevention, early detection, diagnosis and treatment, rehabilitation and palliative care.
Raising public awareness of breast cancer issues and control mechanisms and advocating for appropriate policies and planning are key strategies for population-based breast cancer control. Many low- and middle-income countries now face a double burden of breast and cervical cancers, the number one cancer killer of women over 30 years of age. These countries need to implement joint strategies to address these two public health problems in an efficient and effective manner.
Prevention
Control of modifiable breast cancer-specific risk factors and effective combination of NCD prevention to promote healthy diet, physical activity and control of alcohol consumption, excess weight and obesity can ultimately have an impact and reduce the incidence of breast cancer in the long term.
Early detection
Although some risk reduction may be achieved through prevention, such strategies cannot eliminate the majority of breast cancers that develop in low- and middle-income countries. Therefore, early detection in order to improve breast cancer outcomes and survival remains the cornerstone of breast cancer control (Anderson et al., 2008).
There are two approaches to early detection.
Early diagnosis or noting signs and symptoms in a symptomatic population in order to facilitate diagnosis and early treatment ;
Screening, in which screening tests are systematically applied in a potentially asymptomatic population. The aim is to identify people who present with abnormalities suggestive of having cancer.
Screening planning is much more complex than early diagnosis planning (WHO, 2007).
Regardless of the early detection method used, the key to successful population-based early detection is careful planning and well-organized and sustainable planning that targets the right population and ensures coordination, continuity and quality of actions across the medical continuum. Targeting the wrong age group, such as younger women with a lower risk of breast cancer, can result in a lower number of breast cancers detected per woman screened and therefore can reduce cost effectiveness. In addition, targeting younger women would lead to more evaluation of benign tumors, thus unnecessarily overloading health care facilities with workload due to the use of more diagnostic resources (Yip et al., 2008).
Early diagnosis
Early diagnosis remains an important early detection strategy, especially in low- and middle-income countries, where disease is not diagnosed until late in life and resources are very limited. There is some evidence that these strategies can “downstage” the disease (increase the proportion of breast cancers detected at an early stage) to a stage more suitable for radical therapy (Yip et al., 2008).
Mammography screening
Mammography screening is the only screening method that has been shown to be effective. When screening coverage exceeds 70%, it can reduce breast cancer mortality by 20 to 30% in women over 50 years of age in high-income countries (IARC, 2008). Mammography screening is complex and resource-intensive, and its effectiveness has not been studied in low-resource settings.
Breast self-examination
There is no evidence on the effectiveness of screening by breast self-examination. However, the practice of breast self-examination is believed to empower women to take charge of their own health. Therefore, breast self-examination is recommended as a method of raising awareness among women at risk rather than as a screening method.