Guest post by Katie Leach-Kemon, a policy translation specialist from the University of Washington’s Institute for Health Metrics and Evaluation.
The World Health Organization this week released its World Cancer Report, generating headlines such as:
Global cancer cases are rising mostly due to population growth and the fact that more people are living into older ages in low- and middle-income countries.
Experts warn that in countries with few resources, expensive chemotherapy is rarely an option, and stress that cancer prevention is the most cost-effective approach to combat the rising toll of this disease in these settings. Tools to prevent cancer range from reducing tobacco use through tighter regulation, to human papillomavirus (HPV) vaccines to prevent cervical cancer, and hepatitis B and C vaccines to prevent liver cancer.
In today’s post, we will use data visualization tools based on the Global Burden of Disease (GBD) Study 2010 to visualize these changes in greater depth, looking at trends in different types of cancer over time and comparing patterns across age groups and countries. The screen grabs below show the leading causes of death in developing countries in men and women in 1990 and 2010 and the percent change in deaths from each cause over this period. In females, lung cancer was the 25th-leading cause of death in 1990, but rose to 14th place in 2010. Lung cancer deaths increased by 94% during this time. Breast cancer deaths also went up in rank between 1990 and 2010 and grew by 79%. In males, deaths from lung cancer, liver cancer, and stomach cancer increased by 97%, 67%, and 12%, respectively. While deaths from these different types of cancer are increasing, these graphs illustrate how other communicable and non-communicable diseases rank much higher than cancer. Next, the screen grab below gives you an idea of how the overall volume of cancer cases rose in developing countries between 1990 and 2010. The next screen grab shows how the rate of death from cancer rises in older age groups, underscoring why cancer cases are increasing in low- and middle-income countries as people die at increasingly older ages. What insights can we gain by comparing cancer trends across countries in various phases of development? The next screen grab shows death rates from different types of cancer in females in multiple Latin American countries. The data have been adjusted for differences in population size and ages across countries.
Lower-middle-income countries, including Bolivia, Guatemala, and Honduras, stand out as having higher rates of stomach cancer.
Elevated rates of this cancer in these countries can be attributed to greater exposure to H. pylori infection, which is more common in poorer settings and associated with lack of access to good water and sanitation. Guatemala has a higher rate of liver cancer, which is likely a result of higher hepatitis B and C infection rates.
Another type of cancer that stands out among poorer countries in this figure is cervical cancer. Bolivia, Guatemala, El Salvador, and Nicaragua – all lower-middle-income countries – had higher rates compared to wealthier Latin American countries, largely attributable to lower coverage of cervical cancer screening. However, another lower-middle-income country, Honduras, had the smallest rates of cervical cancer deaths compared to the other countries in the figure. The lower rates of cervical cancer in Honduras need to be interpreted with caution, however, given the challenges inherent in assessing causes of death for a country where the quality of data is not always high and where the small population could lead to underestimates of the true burden of cervical cancer.
Looking at cancer rates in upper-middle-income nations in the screen grab highlights some of the challenges countries may face as their incomes rise. Argentina and Cuba have higher rates of breast cancer than the other countries shown here.
Lack of or low physical activity was linked to more than 30% of breast cancer deaths in Argentina and Cuba. Rates of colon and rectal cancers in these countries are also greater than in the other Latin American countries shown in the figure. This is linked to diet-related risk factors including not consuming enough fiber, calcium, and milk and eating too much red meat.
Cuba stands out as the country with the highest death rates from lung cancer as a result of smoking. Finally, women in Chile have higher rates of gallbladder cancer compared to the other countries; 50% of deaths from this cancer in females were linked to obesity and overweight in 2010.
“We know that behavioral factors can explain some of the variation in trends in gallbladder cancer in Chile and in breast cancer in Argentina, but these factors don’t explain all of the differences across countries,” said Mohsen Naghavi, a lead author of the GBD study and an Associate Professor at IHME. “More research is needed to understand why these types of cancers are higher in these countries.”
An in-depth look at cancer trends in countries across the income spectrum can shed light on key factors that contribute to deaths in different types of settings. These trends reveal how countries such as Bolivia and Guatemala could save lives and money by vaccinating against HPV to prevent cervical cancer, and in the case of Guatemala, vaccinating against hepatitis B and C to reduce deaths from liver cancer.
Also, learning from disease patterns in wealthier Latin American countries underscores how regulating cigarettes and encouraging physical activity and healthy eating in poorer countries could improve health and ease the strain on health budgets in years to come.