The unhealthy consumption of high-calorie food threatens to reverse declines in smoking-related cancers in developed countries, while cancer death rates are expected to increase in developing countries, a new report suggests.
Researchers estimated the burden of cancer in terms of death and disability in different parts of the world. They called it the first such global attempt for 27 types of cancer.
Overall, average premature mortality was higher in lower-income countries, while disability and impairment attributed to cancer were higher in wealthier countries.
Worldwide, an estimated 169.3 million healthy life-years were lost to cancer in 2008, Dr. Isabelle Soerjomataram of the International Agency for Research on Cancer (IARC) in Lyon, France, and her co-authors concluded in Tuesday's issue of The Lancet.
North America, Australia and northern Europe reported cancer mortality declines that were attributed to a reduction in lung and other smoking-related cancers in men and breast cancer in women. But in most countries, cancer mortality is still rising, the researchers said.
"Our findings emphasize the need for increased efforts in cancer control in low-resource settings," the authors wrote.
"The inadequate prevention, early detection and treatment programs in low-income to middle-income countries should be reassessed in view of the predicted long-term increased in the future burden of cancer."
It is difficult to build a model from sparse cancer registry data, but the findings emphasize the growing burden that cancer poses in developing countries, Dr. Ahmedin Jemal of the American Cancer Society in Atlanta said in a journal commentary linked to the study.
Obesity and physical inactivity have been associated with an increased risk of cancers including colorectal, post-menopausal breast, kidney and pancreatic, Jemal said.
"Incidence rates for most of these cancers are on the rise in several countries partly because of the obesity pandemic in recent decades," he wrote. "If no action is taken to halt or reverse these trends, they might wipe out the gains from the reduction in smoking-related cancers, especially in developed countries."
Jemal supported the researchers' call for better cancer control tailored to the needs of developing countries.
The study's authors estimated disability rates for women were highest in eastern African countries such as Uganda and Zimbabwe. For men, the rates were highest in Hungary and Uruguay.
The cancer burden of the developing world partly reflects aging and growth of the population as well as marketing that is driving increased use of tobacco and consumption of high-calorie foods, Jemal said.
He added that there are opportunities to reduce risk factors through:
- Tobacco control.
- Improving opportunity for physical activity and healthier diet patterns.
- Vaccinating against the hepatitis B virus, which causes liver cancer, and human papillomavirus (HPV), which causes some cervical, other genital and oropharyngeal cancers.
- Promoting safe sex and increasing availability of antiretroviral therapy for those who face HIV-infection related cancers in sub-Saharan Africa.
Bacteria and viruses account for about 22 per cent of cancer cases in developing countries, such as stomach cancer caused by H. pylori.
The study was funded by the Dutch Scientific Society, Erasmus University Rotterdam and IARC.