Breast cancer is the top cancer in women both in the developed and the developing world. The incidence of breast cancer is increasing in the developing world due to increase life expectancy, increase urbanization and adoption of western lifestyles. Although some risk reduction might be achieved with prevention, these strategies cannot eliminate the majority of breast cancers that develop in low- and middle-income countries where breast cancer is diagnosed in very late stages. Therefore, early detection in order to improve breast cancer outcome and survival remains the cornerstone of breast cancer control.
Limited resource settings with weak health systems where breast cancer incidence is relatively low and the majority of women are diagnosed in late stages have the option to implement early diagnosis programmes based on awareness of early signs and symptoms and prompt referral to diagnosis and treatment.
Population-based cancer screening is a much more complex public health undertaking than early diagnosis and is usually cost-effective when done in the context of high-standard programmes that target all the population at risk in a given geographical area with high specific cancer burden, with everyone who takes part being offered the same level of screening, diagnosis and treatment services.
So far the only breast cancer screening method that has proved to be effective is mammography screening.
Mammography screening is very costly and is cost-effective and feasible in countries with good health infrastructure that can afford a long-term organized population-based screening programmes. Low-cost screening approaches, such as clinical breast examination, could be implemented in limited resource settings when the necessary evidence from ongoing studies becomes available.
Many low- and middle-income countries that face the double burden of cervical and breast cancer need to implement combined cost-effective and affordable interventions to tackle these highly preventable diseases.
WHO promotes breast cancer control within the context of national cancer control programmes and integrated to noncommunicable disease prevention and control.
Several risk factors for breast cancer have been well documented. However, for the majority of women presenting with breast cancer it is not possible to identify specific risk factors (IARC, 2008; Lacey et al., 2009).
A familial history of breast cancer increases the risk by a factor of two or three. Some mutations, particularly in BRCA1, BRCA2 and p53 result in a very high risk for breast cancer. However, these mutations are rare and account for a small portion of the total breast cancer burden.
Reproductive factors associated with prolonged exposure to endogenous estrogens, such as early menarche, late menopause, late age at first childbirth are among the most important risk factors for breast cancer. Exogenous hormones also exert a higher risk for breast cancer. Oral contraceptive and hormone replacement therapy users are at higher risk than non-users. Breastfeeding has a protective effect (IARC, 2008, Lacey et al., 2009).
The contribution of various modifiable risk factors, excluding reproductive factors, to the overall breast cancer burden has been calculated by Danaei et al. (Danaei et al., 2005). They conclude that 21% of all breast cancer deaths worldwide are attributable to alcohol use, overweight and obesity, and physical inactivity. This proportion was higher in high-income countries (27%), and the most important contributor was overweight and obesity. In low- and middle-income countries, the proportion of breast cancers attributable to these risk factors was 18%, and physical inactivity was the most important determinant (10%).
The differences in breast cancer incidence between developed and developing countries can partly be explained by dietary effects combined with later first childbirth, lower parity, and shorter breastfeeding (Peto, 2001). The increasing adoption of western life-style in low- and middle-income countries is an important determinant in the increase of breast cancer incidence in these countries.
Breast cancer control
WHO promotes breast cancer control within the context of comprehensive national cancer control programmes that are integrated to non communicable diseases and other related problems. Comprehensive cancer control involves prevention, early detection, diagnosis and treatment, rehabilitation and palliative care.
Raising general public awareness on the breast cancer problem and the mechanisms to control as well as advocating for appropriate policies and programmes are key strategies of population-based breast cancer control. Many low- and middle-income countries face now a double burden of breast and cervical cancer which represent top cancer killers in women over 30 years old. These countries need to implement combined strategies that address both public health problems in an effective and efficient way.
Prevention
Control of specific modifiable breast cancer risk factors as well as effective integrated prevention of non-communicable diseases which promotes healthy diet, physical activity and control of alcohol intake, overweight and obesity, could eventually have an impact in reducing the incidence of breast cancer in the long term.
Early detection
Although some risk reduction might be achieved with prevention, these 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 outcome and survival remains the cornerstone of breast cancer control .
There are two early detection methods:
- early diagnosis or awareness of early signs and symptoms in symptomatic populations in order to facilitate diagnosis and early treatment, and
- screening that is the systematic application of a screening test in a presumably asymptomatic population. It aims to identify individuals with an abnormality suggestive of cancer.
A screening programme is a far more complex undertaking that an early diagnosis programme.Irrespective of the early detection method used, central to the success of population based early detection are careful planning and a well organized and sustainable programme that targets the right population group and ensures coordination, continuity and quality of actions across the whole continuum of care. Targeting the wrong age group, such as, younger women with low risk of breast cancer, could cause a lower number of breast cancers found per woman screened and therefore reduce its cost-effectiveness. In addition, targeting younger women would lead to more evaluation of benign tumours, which causes unnecessary overload of health care facilities due to the use of addition diagnostic resources (Yip et al., 2008).
Early diagnosis
Early diagnosis remains an important early detection strategy, particularly in low- and middle-income countries where the diseases is diagnosed in late stages and resources are very limited. There is some evidence that this strategy can produce “down staging” (increasing in proportion of breast cancers detected at an early stage) of the disease to stages that are more amenable to curative treatment (Yip et al., 2008).
Mammography screening
Mammography screening is the only screening method that has proven to be effective. Although there is evidence that organized population-based mammography screening programmes can reduce breast cancer mortality by around 20% in the screened group versus the unscreened group across all age groups, in general there appears to be a narrow balance of benefits compared with harms, particularly in younger and older women. There is uncertainty about the magnitude of the harms – particularly overdiagnosis and overtreatment. Mammography screening is very complex and resource intensive and no research of its effectiveness has been conducted in low resource settings.
Breast self examination (BSE)
There is no evidence on the effect of screening through breast self-examination (BSE). However, the practice of BSE has been seen to empower women, taking responsibility for their own health. Therefore, BSE is recommend for raising awareness among women at risk rather than as a screening method.
Clinical Breast Examination (CBE)
Research is underway to evaluate CBE as a low-cost approach to breast cancer screening that can work in less affluent countries. Promising preliminary results show that the age-standardized incidence rate for advanced-stage breast cancer is lower in the screened group compared to the unscreened group (Sankaranarayanan, 2011)
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https://www.who.int/cancer/detection/breastcancer/en/index3.html