New cases of virtually all types of cancer are rising in countries globally - regardless of income - but the death rates from cancer are falling in many countries, according to a new analysis of 28 cancer groups in 188 countries.
Thanks to prevention and treatment, progress has been made in fighting certain cancers, such as childhood leukemia. But researchers found that of all the cancers studied, there was just one - Hodgkin lymphoma - where the number of new cases dropped between 1990 and 2013. Over the same period, age-standardized death rates for all cancers fell in 126 out of 188 countries.
Published in JAMA Oncology on May 28, the study, "The Global Burden of Cancer 2013," was conducted by an international consortium of researchers led by the Institute for Health Metrics and Evaluation (IHME) at the University of Washington.
In 2013, there were 14.9 million new cancer cases and 8.2 million cancer deaths worldwide. The leading cause of cancer incidence for men was prostate cancer, which caused 1.4 million new cases and 293,000 deaths. Prostate cancer cases have increased more than threefold during this period due in part to population growth and aging.
For women, similar factors contributed to the rise in breast cancer incidence. In 2013 there were 1.8 million new cases of breast cancer and 464,000 deaths. Breast cancer has remained the leading cause of incident cancer cases for women between 1990 and 2013, but the number of new cases doubled during this period.
Other leading causes of incident cases globally include colon and rectum cancers, which have increased 92%, stomach cancer, up 23% since 1990, and liver cancer, with a 70% increase.
"Cancer remains a major threat to people's health around the world," said oncologist Dr. Christina Fitzmaurice, a Visiting Fellow at IHME and lead author of the study. "Cancer prevention, screening, and treatment programs are costly, and it is very important for countries to know which cancers cause the highest disease burden in order to allocate scarce resources appropriately."
The death toll from cancer is also changing as new cases increase. Cancer was the second-leading cause of death globally after cardiovascular disease, and the proportion of deaths around the world due to cancer has increased from 12% in 1990 to 15% in 2013. Lung, stomach, and liver cancer have remained the three leading causes of cancer deaths for both sexes combined during this time period. Lung cancer deaths have increased by 56%, stomach cancer deaths by 10%, and liver cancer deaths by 60%.
Cancer is often seen as a problem primarily in more affluent nations, but the disease is an issue in developing countries as well as developed countries. Even though breast cancer remains the leading cause of incident cancer cases for women globally, in developed countries incidence rates have been stable or declining since the early 2000s. The reverse is true in developing countries, where incidence rates are lower but rising faster than in developed countries.
The rankings for developed and developing countries are largely the same when it comes to cancer deaths for both sexes, though there are some notable differences. Cervical cancer ranks eighth in developing countries, compared to 18th in developed countries, and prostate cancer ranks 13th in developing countries but sixth in developed countries. Cervical cancer has a particularly significant impact in sub-Saharan Africa, where it's the most commonly diagnosed cancer in almost two dozen countries in the region, including Ghana, Nigeria, and Zambia, and the most common cause of cancer death for women in 40 countries, such as Ethiopia, Kenya, and Tanzania.
"With better screening and treatment sub-Saharan Africa can lead the way in the fight against cervical cancer," said Mr. Yohannes Adama Melaku, of Mekelle University in Ethiopia and a co-author of the study. "Prevention will be a critical part of the effort to save lives."
Although cancer is a global phenomenon, countries around the world show important variations. In China, stomach cancer, not breast cancer, is the second-most common cause of cancer death for women. Non-Hodgkin lymphoma is the most commonly diagnosed cancer for men in United Arab Emirates and Qatar rather than prostate cancer. Mouth cancer, which is not prominent globally, is the second-most diagnosed cancer in India. Japan, Norway, Portugal, Spain, and Sweden are the only countries in the world where colon and rectum cancer was the most deadly form of cancer for women.
"The most effective strategies to address cancer will be tailored to local needs," said IHME Director Dr. Christopher Murray. "Country-specific data can drive policies aimed to reduce the impact of cancer now and in the future."
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