The study, published in Cancer Epidemiology, Biomarkers & Prevention, looked at global cancer incidence and mortality rates up until 2012. Deaths from breast cancer, for example doubled in Zimbabwe and Uganda between 1992 and 2007.
A team led by Lindsey Torre, an epidemiologist at the American Cancer Society in Atlanta, United States, found that low- to middle income countries had the highest rates of infection-related cancers in the world.These include stomach cancer, associated with infection by Helicobacter pylori bacteria; liver cancer, linked with hepatitis B or C virus infection; and cervical cancer, which is associated with human papilloma virus (HPV) infection. Cervical cancer was identified as the third-highest cause of cancer-related deaths among women in developing countries in the study, but was found to be rare in high-income countries. In the timeframe studied, Zimbabwe saw an average of 87 deaths per 100,000 women from cervical cancer, while in Malawi and Uganda death rates stood at 76 and 54 women out of 100,000, respectively. These rates are more than twice as high as those in all other cancer databases studied as part of the research, the authors say. The study adds that around 21 per cent of African women have a HPV infection at any given time, compared with just five per cent in North America.
Although high-income countries still have the highest rates of cancer overall, incidence and mortality are declining because of improvements in screening and diagnostics. For example, the rates of cervical cancer have decreased by around 70 per cent in high-income countries since screening was introduced, the study found.
By contrast, “neither urban nor rural Africans have access to treatments and diagnostics of reasonable quality”, says Clement Adebamowo, director of the Nigerian National System of Cancer Registries.
“Given the high level of poverty, poor follow-up culture and low levels of education, most patients cannot afford therapy, fail to complete treatment and are impoverished by treatment.”
Clement Adebamowo, Nigerian National System of Cancer Registries
The rates of ‘lifestyle’ cancers, which are caused by obesity, physical inactivity and smoking, are also increasing in low- to middle income countries, the study found. Taken together, this growth in cancer prevalence is likely to overwhelm the healthcare systems of poor countries, which are still dealing with a high burden of infectious diseases, says Torre.
“They might just not have the resources to deal effectively with prevention and appropriate treatment, and also palliative care,” she says.
Adebamowo agrees. “Given the high level of poverty, poor follow-up culture and low levels of education, most patients cannot afford therapy, fail to complete treatment and are impoverished by treatment,” he says.
To help the healthcare systems, it will be important to invest in prevention, believes Adebamowo. According to Torre, this could include restrictions on tobacco sale, improved screening for cancer and initiatives to make vaccines for infections such as HPV and hepatitis B available and affordable.