THURSDAY, Feb. 4, 2021 (HealthDay News) -- Breast cancer has surpassed lung cancer as the world's most commonly diagnosed cancer.
In 2020, there were an estimated 19.3 million new cancer cases and nearly 10 million cancer deaths worldwide, according to the Global Cancer Statistics 2020 report from the American Cancer Society (ACS) and the International Agency for Research on Cancer.
Overall, 1 in 5 people get cancer during their lifetime; 1 in 8 men and 1 in 11 women die from the disease.
Female breast cancer was the most commonly diagnosed cancer last year, with an estimated 2.3 million new cases (11.7%), followed by lung (11.4%), colon (10%), prostate (7.3%), and stomach (5.6%) cancers, according to the study.
The report -- published Feb. 4 in CA: A Cancer Journal for Clinicians -- looked at 10 major cancer types that account for more than 60% of new diagnoses and more than 70% of cancer deaths.
It found that breast cancer is on the rise in countries where rates had historically been low.
"Dramatic changes in lifestyle and built environment have had an impact on the prevalence of breast cancer risk factors such as excess body weight, physical inactivity, alcohol consumption, postponement of childbearing, fewer childbirths, and less breastfeeding," the authors said in an ACS news release.
These factors, along with changes as countries go through periods of social and economic transition have narrowed international gaps in cancer rates, researchers said.
Breast cancer death rates in transitioning countries were higher than in transitioned countries (15 and 12.8 per 100,000, respectively), despite the substantially lower incidence rates (29.7 and 55.9 per 100,000, respectively), the report said.
The poor outcome in these countries largely owes to later diagnosis and treatment, the authors said.
"Efforts to promote early detection, followed by timely and appropriate treatment, are urgently needed through the implementation of evidence-based and resource-stratified guidelines," lead author Hyuna Sung, principal scientist at the ACS, said in the release.
Lung cancer remained the leading cause of cancer death in 2020, with an estimated 1.8 million deaths (18%), followed by cancers of the colon (9.4%), liver (8.3%), stomach (7.7%), and female breast (6.9%).
While lung cancer death rates are up to four times higher in transitioned countries than in transitioning ones, this pattern may change because 80% of smokers are in low- and middle- income nations, according to the study.
About two-thirds of lung cancer deaths worldwide are due to smoking, according to the study.
It forecast 28.4 million new cancer cases worldwide in 2040 -- up 47% from 2020.
If not controlled, the rising cancer rates in transitioning countries could overwhelm their health care systems, researchers warned.
The U.S. National Cancer Institute has more on cancer causes and prevention.
SOURCE: American Cancer Society, news release, Feb. 4, 2021