Wednesday, August 20, 2014
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Tropics of Cancer?

STANFORD – Cancer is sometimes thought of as a disease of wealthier countries, but it is a major cause of morbidity and mortality in poorer ones as well. Indeed, by the end of this decade, about 150 million people worldwide will have cancer, with approximately 60% of them residing in developing countries.

Although fewer people in developing countries live to the age at which cancer is most prevalent, inadequate nutrition and environmental exposures to viruses and toxins, combined with a paucity of diagnostic and treatment options, increase cancer’s incidence and lethality. Many people in poor countries die from cancers that are preventable or treatable in wealthier societies, but they often succumb to other scourges as well, such as infectious diseases. So what could and should be done about this conundrum?

Margaret Chan, the head of the World Health Organization, and Yukiya Amano, director of the International Atomic Energy Agency (IAEA), noted in a recent article that most developing countries’ health-care systems are designed to cope with infectious diseases rather than cancer. I find this to be a rational strategy, given the heavy toll that infections take, and that many can be prevented and treated at a relatively modest cost.

The diagnosis and treatment of most types of cancer in developing countries would require a huge and daunting investment in infrastructure. As Chan and Amano point out:

“[M]ost lack the funds, equipment, and qualified personnel needed to provide basic care for cancer patients. Thirty countries – half of them in Africa – do not have a single radiotherapy machine. And these countries certainly do not have the financial resources, facilities, equipment, technology, infrastructure, staff, or training to cope with the long-term demands of cancer care.”

In order to begin addressing these deficiencies, “The IAEA’s work involves building countries’ capacity for radiation medicine. But technology means nothing without well-trained and motivated staff to use it.”

Such an approach is, however, poorly focused and unlikely to be cost-effective. As the United Nations’ own data make clear, infectious diseases, many of them preventable and treatable, remain the scourge of poorer populations. In 2008, about 250 million cases of malaria caused almost a million deaths, mostly of children under five. In virtually all poor, malaria-endemic countries, there is inadequate access to antimalarial medicines (especially artemisinin-based combination therapy).

The incidence of malaria could be reduced drastically by the judicious application of the mosquito-killing chemical DDT, but UN and national regulators have curtailed its availability, owing to misguided notions about its toxicity. Hundreds of millions suffer from other neglected tropical diseases, including lymphatic filariasis and cholera.

Although new HIV infections worldwide declined slightly during the past decade, 2.7 million people contracted the virus in 2008, and there were two million HIV/AIDS-related deaths.  By the end of that year, more than four million people in low- and middle-income countries were receiving anti-retroviral therapy, but more than five million who were HIV-positive remained untreated. The number of new cases of tuberculosis cases worldwide is increasing, and the growing emergence of multidrug-resistant strains of the bacteria is especially worrisome.

According to UN statistics, about 15% of the world’s population lacks access to safe drinking water, and “in 2008, 2.6 billion people had no access to a hygienic toilet or latrine,” while “1.1 billion were defecating in the open.” Primitive approaches to managing sewage continue to spread infections such as schistosomiasis, trachoma, viral hepatitis, and cholera.

Many cancers are likely caused by chronic viral infections, another reason that it is surely more sensible to attack infectious diseases by improving access to clean water, basic sanitation, antibiotics, and vaccines than it is to build radiotherapy facilities. In some technology-poor but oil-rich Middle East countries, state-of-the-art radiotherapy (and cardio-pulmonary bypass) equipment has been delivered, but never used, or has been damaged by electrical surges or power outages. And many poor countries do not have a single medical school, and when their citizens study abroad, they often stay there, or are ill-equipped for a low-tech milieu that is so different from where they trained.

Although the use of big-ticket equipment, expensive chemotherapy drugs, and sophisticated and complex procedures such as bone marrow transplantation would not be wise, this is not to say that we should give up entirely on cancer treatment in developing countries. Sometimes, prevention, diagnosis, and treatment are cost-effective. Vaccines to prevent hepatitis A and B (and C, when one becomes available) reduce the incidence not only of the viral infections, but also of sequelae such as cirrhosis and hepatic carcinoma. And public-health efforts to curb air pollution and smoking could reduce the prevalence of lung cancer in Asia and Africa.

Another example is cervical cancers, many of which can be prevented by vaccines against human papilloma virus. And acetic acid can be used to visualize cervical cancers, which can then be treated with cryotherapy (freezing).

The bottom line is that in a world of limited health-care resources, we need to make hard decisions that will deliver high-impact outcomes for the most people at the least cost.

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