THURSDAY, May 31 (HealthDay News) -- The worldwide incidence of cancer is expected to increase 75 percent by 2030, with a projected increase of more than 90 percent in the poorest nations, a new study reveals.

Rates of certain types of cancer (such as cervical and stomach cancer) appear to be declining in some developing countries, but these reductions are likely to be offset by substantial increases in the types of cancer associated with a "westernized" lifestyle, including breast, prostate and colorectal cancer, according to the report published online May 31 in The Lancet Oncology.

For the study, researchers analyzed International Agency for Research on Cancer (IARC) data from 184 countries in 2008 in order to examine how current and future cancer trends vary between countries based on their levels of development, as measured by their Human Development Index (HDI).

Currently, countries with a low HDI (mainly nations in sub-Saharan Africa) have a high incidence of cancers associated with infection (particularly cervical cancer), as well as liver cancer, stomach cancer and Kaposi's sarcoma. Countries with a higher HDI (such as Australia, Brazil, Russia and the United Kingdom) have higher rates of cancers associated with smoking (lung cancer), reproductive risk factors, obesity and diet (breast, prostate and colorectal cancer).

Improved living standards in countries with a lower HDI may lead to a decrease in some infection-related cancers, but these countries may see a sharp increase in the types of cancer currently seen in higher-development countries, the researchers pointed out in a journal news release.

Cancer incidence rates could increase by 93 percent in low HDI countries by 2030, and by 78 percent in medium HDI countries (such as South Africa, China and India) over the same period, according to study leader Dr. Freddie Bray, of IARC, and colleagues.

The investigators also found that rates of prostate cancer and female breast cancer appear to be rising in most countries with medium, high or very high levels of development, and that rates of stomach cancer and cervical cancer are generally decreasing in countries with medium, high or very high levels of HDI.

Lung cancer is currently not a leading type of cancer in low HDI countries, but that will change unless smoking is effectively controlled in these countries, the study authors noted in the news release.

The researchers also found that 40 percent of worldwide cancer cases in 2008 occurred in countries with very high HDI levels, even though they had just 15 percent of the global population.

More information

The World Health Organization has more about cancer.