Recent trends also highlight global disparities in cancer burden — ScienceDaily

According to a new scientific study from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington School of Medicine, the number of cancer deaths rose to 10 million and the number of new cases rose to more than 23 million worldwide in 2019.

At the start of the decade in 2010, the total number of cancer deaths worldwide was 8.29 million and new cancer cases 18.7 million; the censuses by the end of the decade in 2019 represent an increase of 20.9% and 26.3% respectively.

The paper was published in JAMA Oncology on December 30, 2021 and is part of the Global Burden of Diseases, Injuries, and Risk Factors Study 2019 (GBD 2019).

The researchers estimate cancer burden and trends worldwide for 204 countries and territories. They found that cancer was second only to cardiovascular disease in deaths, disability-adjusted life years (DALYs), and life years lost (YLLs) among 22 groups of diseases and injuries worldwide in 2019. Within the total cancer burden, the five leading causes of cancer-related DALYs for both sexes together were tracheal, bronchial, and lung cancers (TBL); colon and rectal cancer; stomach cancer; breast cancer; and liver cancer. TBL cancer was the leading cause of cancer death in 119 countries and territories for men and 27 countries and territories for women.

While the absolute burden of cancer increased between 2010 and 2019, both in deaths and new cases, global age-standardized mortality and incidence rates decreased by 5.9% and 1.1%, respectively. From a country perspective, the age-standardized mortality rate has decreased in 131 countries and territories and the age-standardized incidence has decreased in 75 countries and territories. The small percentage declines worldwide are promising, but the researchers warn that there may be setbacks in cancer care and outcomes due to COVID-19. The effects of the pandemic on morbidity, mortality and cancer prevention and control were not included in this GBD study, which analyzed the global cancer burden up to 2019.

The authors also analyzed cancer burden based on the socio-demographic index (SDI), a composite measure of per capita income, average number of years of education, and total fertility rate for those under age 25.

While the global trend for age-standardized mortality and incidence rates is encouraging, the decline in rates appears to be driven by higher SDI sites. For mortality, the age-standardized rates decreased in the middle, middle and high quintiles and increased in the low and low middle quintiles. Similarly, for incidence, the age-standardized rates decreased in the high-mid and high quintiles — with the greatest decrease in the high SDI quintile — while they increased in the low, low-middle, and mid SDI quintiles.

“It is critical to ensure that global progress in the fight against the cancer burden is equitable,” said Dr. Jonathan Kocarnik, lead author of the study and research scientist at IHME. “This requires efforts to reduce disparities in cancer prevention, treatment and survival, and the integration of local needs and knowledge into tailor-made national cancer control plans.”

dr. Kocarnik and his co-authors suggested that the larger increases in the lower SDI quintiles likely reflect ongoing epidemiological transitions, demographic shifts and disparities in cancer prevention, care and control. Even without taking into account the COVID-19 pandemic, the absolute burden of cancer worldwide is already increasing significantly.

Some additional findings from the study:

Breast cancer was the leading cause of cancer-related deaths among women worldwide, including in 119 countries. Worldwide, 96.9% of cancer-related DALYs, which is the sum of YLLs and years with disabilities, can be attributed to YLLs or premature death. Of the 22 disease and injury groups in the GBD study, total cancer is the leading cause of DALYs for the high SDI quintile and in the top five causes of DALYs for three of the remaining four SDI quintiles.

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