Cancer
Cancer is another noncommunicable disease long considered a health threat primarily for high-income countries, but now imposing a considerable disease burden worldwide.3 In 2001, cancer caused more than 7 million deaths, of which 5 million were in low- and middle-income countries. That year, cancer resulted in the loss of more than 100 million DALYs, with nearly 75 million lost in low- and middle-income countries. By 2020, unless cancer prevention and screening interventions effectively reduce the incidence of cancer, the number of new cancer cases will increase from an estimated 10 million cases in 2000 to an estimated 15 million per year, and 9 million of them will occur in developing countries.
While cancer is a problem everywhere, it is not manifested in the same way worldwide. A substantial portion of cancers in developing countries, up to 25 percent, are associated with chronic infection. Liver cancer is causally associated with hepatitis B infection, cervical cancer with infection by certain types of human papillomavirus, and stomach cancer with Helicobacter pylori infection. The incidence of these cancers is also related to the absence of a well-developed public health infrastructure for the control of cancer-causing infectious agents.
In 2000, seven types of cancer accounted for approximately 60 percent of all newly diagnosed cancer cases and cancer deaths in developing countries: cervical, liver, stomach, esophageal, lung, colorectal, and breast. The first four exhibit elevated incidence and mortality rates in developing countries. The last three have a lower but increasing incidence because of demographic and industrial transitions. Developing regions also exhibit considerable variation in their cancer burdens. Deaths from liver cancer are relatively high in East Asia and Africa because of the high prevalence of chronic hepatitis B infection and inadequate food storage and preservation in those regions. Deaths from colorectal and breast cancer are relatively high in Eastern Europe as people in those regions have adopted less healthy, high-fat diets and more sedentary lifestyles. Deaths from oral cancer are particularly high in South Asia, where chewing betel quid is common. These different types of cancer call for different intervention strategies.
Interventions fall into several categories. Primary prevention eliminates exposure to cancer-causing agents; secondary prevention involves detecting and treating precancerous lesions; treatment includes surgery, chemotherapy, and radiotherapy; and palliative care addresses patients' physical and psychological comfort from diagnosis through death.
Primary prevention for the types of cancer that are of greatest concern in developing countries include immunizing against and treating infectious agents, implementing dietary interventions, introducing tobacco control programs, reducing excessive alcohol consumption, and using chemoprophylaxis. Cost-effectiveness studies of these interventions are relatively rare and are concentrated in high-income countries. For example, studies in the United Kingdom and the United States find that the costs of screening and treating individuals for helicobacter infections to reduce the risk of stomach cancer run between US$25,000 and US$50,000 per life year saved, but another study found that this intervention would be much more cost-effective in Colombia, where health care costs are lower and the prevalence of stomach cancer is higher.
Secondary prevention consists of screening programs to detect and treat precursors of cancer, which can prevent or reduce the incidence of highly invasive cancers, such as cervical or colorectal cancers. Effective screening can also detect invasive cancers, such as breast and lung cancers, at an earlier stage than would otherwise be possible and thus improve the likelihood that treatments will be successful. The cost-effectiveness of secondary prevention depends on many factors, including the costs of diagnostic tests, the prevalence of the disease, and the availability of effective treatments.
"Treatment cost-effectiveness for cervical, breast, oral, and colorectal cancer ranges from US$1,300 to US$6,200 per year of life saved. For . . . liver, lung, stomach, and esophageal cancer, the cost-effectiveness is much worse . . ."
Cancer treatment includes surgical removal of tumors, chemotherapy, and radiation therapy. Treatment cost-effectiveness for cervical, breast, oral, and colorectal cancer ranges from US$1,300 to US$6,200 per year of life saved. For cancers that are more difficult to treat, such as liver, lung, stomach, and esophageal cancer, the cost-effectiveness is much worse, ranging from US$53,000 to US$163,000 per year of life saved.
The availability of cost-effective methods of prevention and treatment for cancers in low- and middle-income countries varies significantly depending on the type of cancer, with a consequent substantial effect on the equity of outcomes. In the case of cancers for which effective detection and treatment are not available, that is, esophageal, liver, lung, and pancreatic cancer, survival rates are similar in rich and poor countries. For cancers with proven methods of treatment, such as large bowel, breast, ovarian, and cervical cancer, a substantial gap is apparent between the better survival rates in high-income countries and the worse survival rates in low- and middle-income countries. A third group of cancers requires treatments that are complex and multimodal, including testicular cancer, leukemia, and lymphoma. The challenges to providing appropriate care for these cancers are particularly large in settings without specialized medical staff and good health care infrastructure.
