Cancer Control Opportunities in Low- and Middle-Income Countries (2007) / Chapter Skim
Currently Skimming:
2 Cancer Causes and Risk Factors and the Elements of Cancer Control
2 Cancer Causes and Risk Factors and the Elements of Cancer Control
Pages 27-68
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 27... ...
Chapter 7 is devoted entirely to palliative care, the other major pillar of cancer management, so that area is not covered in this chapter. CAUSES OF AND RISK FACTORS FOR CANCER IN LMCS Knowing the causes of cancer provides a basis for understanding the potential for preventing cancer.
|
From page 28... ...
Main Risk Factors Distribution Strategies % Lung, trachea, Tobacco use Zero exposure Tobacco control 60 and bronchus possible as outlined in (770,938) Framework Convention on Tobacco Control (FCTC)
|
From page 29... ...
Future: Drugs to clear infection? Low fruit and 600 grams/day fruit Dietary improvements 19 vegetable intake and vegetable intake for adults Tobacco use Zero exposure Tobacco control as 11 possible outlined in FCTC Liver Chronic hepatitis Zero exposure Hepatitis B 59a (504,407)
|
From page 30... ...
Dietary improvements 9 obesity of 21 and exercise Low fruit and 600 grams/day fruit Dietary improvements 2 vegetable intake and vegetable intake for adults Esophagus Tobacco use Zero exposure Tobacco control as 37 (379,760) possible outlined in FCTC Alcohol use Zero exposure Reduced alcohol use 24 possible Low fruit and 600 grams/day fruit Dietary improvements 19 vegetable intake and vegetable and exercise intake for adults Breast Physical inactivity At least 2.5 hours/ Exercise 10 (317,195)
|
From page 31... ...
lower radon Improved building exposure possible practices to exclude radon Tobacco use Zero exposure Tobacco control as 6 possible outlined in FCTC Various Lower exposures Workplace regulation 2b occupational possible (varying and controls exposures by exposure) NOTE: PAFs from the Global Burden of Disease and Risk Factors (Lopez et al., 2006)
|
From page 32... ...
, are factors such as occupational exposures to asbestos, coal, and other substances; indoor smoke from cooking and heating; and air pollution, which can cause cancer and a larger burden of chronic respiratory diseases. Beyond these factors, the common cancers in LMCs do not share significant risk factors with other chronic diseases.
|
From page 33... ...
and hepatitis C virus, human papillomavirus (HPV) , and Helicobacter pylori -- follow tobacco in importance as risk factors for cancer incidence in developing countries.
|
From page 34... ...
Main Risk Factors Distribution All cancers Tobacco use Zero exposure possible (~5 million cancer deaths) All carcinogenic infections HBV and HCV Zero exposure possible HPV Zero exposure possible H
|
From page 35... ...
; elimination of one or another could prevent a particular cancer from occurring. This means that the PAFs are not mutually exclusive, and added together will generally overestimate the cancer reduction possible by eliminating all identified risk factors.
|
From page 36... ...
. The most significant is Epstein-Barr fig 2-1 virus, a risk factor for Burkitt's lymphoma and cancers of the nasopharynx, to which 2 percent ofthis is asinfixed image, bnitmapBothjpeg, cancers LMCs are attributable.
|
From page 37... ...
Global Burden of Disease and Risk Factors (Lopez et al., 2006) made separate estimates for the three components, based on the best available quantitative evidence and focusing on low fruit and vegetable intake as the best established specific dietary factor.
|
From page 38... ...
Clearly, cancer control authorities in LMCs should join efforts to improve diet and encourage appropriate physical activity in their own countries. Alcohol Use Cancers of the oral cavity, pharynx, larynx, esophagus, liver, and breast can be caused by heavy alcohol drinking, with the risk varying by cancer site, but increasing for all sites with greater consumption and resulting in an estimated 5 percent of attributable cancer deaths in LMCs (Lopez et al., 2006)
|
From page 39... ...
The World Health Organization (WHO) undertook a thorough assessment of worldwide data for five occupational risk factors, one of which was carcinogens (the others were risks for injuries, airborne particulates, ergonomic risks for back pain, and noise)
|
From page 40... ...
is indoor tobacco smoke. The number of cancer deaths caused by indoor and outdoor air pollution is exceeded by deaths from respiratory and some cardiovascular conditions in adults and deaths from acute respiratory infections in children.
|
From page 41... ...
Certain aflatoxins and chronic infection with HBV together are the main risk factors for liver cancer in parts of Africa, Asia, and South America. Improved storage conditions can greatly reduce aflatoxin contamination (see Chapter 6)
|
From page 42... ...
It is well established that an early age at first birth protects women against cancers of the breast, endometrium, and ovary, and that having no children is associated with higher risks. Even obesity, which alters the circulating levels of various hormones, increases the risk of breast cancer in post-menopausal women, apparently at least in part through this mechanism (Stewart and Kleihues, 2003)
|
From page 43... ...
It is not a focus of this report, however. Medical radiation from diagnostic X-rays and radiotherapy represents almost 40 percent of the global human exposure to ionizing radiation worldwide, but is likely to be substantially less in LMCs, where the use of these technologies is far lower.
|
From page 44... ...
, cancer management -- diagnosis and treatment, including palliative care delivered by a multidisciplinary team -- and psychosocial support for patients and families. Details of what is most important and what is feasible vary according to the cancer burden and the resources available.
|
From page 45... ...
Planning: "A practical guide for programme managers on how to plan overall cancer control effectively, according to available resources and integrating cancer control with programmes for other chronic diseases and related problems." 2. Prevention: "A practical guide for programme managers on how to implement effective cancer prevention by controlling major avoidable cancer risk factors."
|
From page 46... ...
[and] can also contribute to preventing other chronic diseases that share the same risk factors.
|
From page 47... ...
Resolution WHA51.18 noted that non communicable diseases, including cancer, represented a significant and growing burden on public health services; resolution WHA53.17 urged the establishment of comprehensive programmes for the prevention and control of major noncommunicable diseases; resolution WHA55.23 urged the development of a global strategy on diet, physical activity and health; and resolution WHA56.1 adopted the WHO Framework Convention on Tobacco Control. SOURCE: World Health Assembly (2005)
|
From page 48... ...
Developing primary prevention strategies requires knowing something about the causes or risk factors associated with the cancer. If the cause or risk factor can be eliminated or reduced, prevention is possible through behavior modification, modification of the environment, or in the case of infectious agents, vaccination or treatment.
|
From page 49... ...
Fortunately, specific interventions are known to work at reducing tobacco use. Tobacco control is the subject of Chapter 5 of this report.
|
From page 50... ...
For difficult-to-treat cancers, the many cancers of all types not seen until they are advanced beyond probable cure, and other cancers that advance despite treatment, palliative care alone may be most appropriate. Psychosocial services to help deal with the psychological and social impacts of cancer can be appropriate for virtually all people with cancer, and for the survivors of those who die from cancer.
|
From page 51... ...
· spread into lymph nodes · cell type and grade of tumor (i.e., how closely the cancer cells resemble normal tissue) · spread to distant sites (i.e., metastases)
|
From page 52... ...
. I, II, III Higher numbers indicate more extensive disease: greater tumor size, and/or spread of the cancer to nearby lymph nodes and/or organs adjacent to the primary tumor.
|
From page 53... ...
and regional lymph nodes, often with additional treatment modalities. In the United States, about 90 percent of cures of solid tumors are through surgery alone or with other modalities.
|
From page 54... ...
How Radiotherapy Works Different types of cells -- normal and malignant -- vary in their susceptibility to ionizing radiation. Clinical radiotherapy schedules are designed to exploit the differences between normal tissues and tumors, so that as many malignant cells as possible are killed, while damage to normal tissue is minimized.
|
From page 55... ...
, collectively known as "megavoltage machines." Cobalt machines and linacs deliver very high-energy, highly focused beams that can reach deeper tumor tissues while depositing relatively small doses in the normal tissues through which they pass. Linacs produce the same intensity of radiation throughout operation, but the machines are more complex than cobalt machines and require greater manpower and attention to maintain them.
|
From page 56... ...
; · The tumor is advanced with a high risk of local recurrence after surgery, such as rectal cancer; · An inoperable cancer can be rendered operable, such as when advanced rectal cancers that are adhered to other organs, preventing complete excision, can be shrunk by radiation; · The surgery included too small a margin of normal tissue around the tumor to preclude a high likelihood of local recurrence; radiotherapy reduces that likelihood. Chemotherapy may improve the results of radiotherapy in the treatment of some cancers (Table 2-5)
|
From page 57... ...
. enhanced tumor response with two modalities, and the use of chemical agents to protect normal tissues from radiation damage, allowing a greater radiation dose.
|
From page 58... ...
These include surgical and medical oncology, pathology, imaging, general and specialist medical and surgical services, and nursing and psychosocial support services. The costs of radiotherapy include the capital costs of the building and equipment, maintenance costs, and staff salaries.
|
From page 59... ...
(Drugs that improve the quality of life of cancer patients during their illness and at the end of life by controlling pain and other symptoms are considered separately in the discussion of palliative care in Chapter 8.) Medical oncologists are the medical professionals trained in the use of chemotherapy.
|
From page 60... ...
Hormonal · Includes adrenocorticosteroids, estrogens, antiestrogens, progesterones, agents and androgens that modify the growth of certain hormone-dependent cancers. · Tamoxifen, used for estrogen-dependent breast cancer, is an example.
|
From page 61... ...
Dexamethasone Injectable liquid Hydrocortisone Powder for injection Prednisolone Tablet Tamoxifen Tablet Medicines Used in Palliative Careb The WHO Expert Committee on the Selection and Use of Essential Medicines recommended that all the drugs mentioned in the second edition of the WHO publication Cancer Pain Relief (WHO, 1996) be considered essential.
|
From page 62... ...
Adjuvant chemotherapy is given either before or after surgery (or both) to kill both remaining cancer cells at the primary site and cells that are circulating or lodged at distant sites where, left unchecked, they may proliferate into metastatic lesions.
|
From page 63... ...
, for some cases of lung cancer. Other tar geted therapies cause cancer cells to die (undergo apoptosis)
|
From page 64... ...
This form of support can be made available at all stages of the cancer experience -- at diagnosis, during treatment, and beyond, including during palliative care. Support may also be needed by family members and others close to the patient.
|
From page 65... ...
The types of services most needed by cancer patients are likely to be similar around the world, but the providers who are available and have sufficient training will vary according to the health care system, as will the resources available, and other social and cultural factors. SUMMARY AND RECOMMENDATION The review of causes and risk factors and of cancer control elements sets the stage for the latter chapters of this report, where the greatest opportunities for cancer control are identified.
|
From page 66... ...
These decisions and others about cancer control at a national level are best approached through a formal process that weighs the opportunities against the costs within the country context. National cancer control planning and the development of national cancer control programs is the obvious means for making such decisions.
|
From page 67... ...
2006. Global Burden of Disease and Risk Factors.
|
From page 68... ...
2005. Cancer prevention and control.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.