Cancer cases worldwide are expected to soar in the coming decades, a report finds. Here’s why.

Annual cancer cases are projected to rise considerably worldwide by 2050, according to a World Health Organization report on cancer published Wednesday. With its assessment, the United Nations body tempered optimism about improvements in cancer surveillance and treatment and warned that global health care inequities are driving further cases and deaths.

Around 20.6 million people were diagnosed with cancer in 2024, according to the findings. That number could reach 35 million a year by 2050.

The new cases will disproportionately appear in lower-income countries with poorer access to cancer surveillance and treatment, according to the report.

“Far too many people are still being left behind,” André Ilbawi, the team lead for cancer control at the WHO, said at a news conference about the study this week.

Here are some of the report’s key findings:

The WHO projects that cancer incidence will increase by around 67% globally by 2050. That’s in line with predictions made in other recent reports.

The reasons for the increasing cancer rates are complex. Two key drivers the WHO’s report highlights are exposure to known risk factors, such as smoking and alcohol, and an aging population.

Experts have also cited improvements in cancer surveillance, which has allowed doctors to detect and diagnose more cancers than before.

In the United States, the rate of new cases has generally been stable in recent years, according to the National Institutes of Health. The WHO report predicts that cancer rates will increase in all regions across the world, though the biggest increases are projected in Africa and the Eastern Mediterranean region.

Cancer caused 9.7 million deaths globally in 2024, according to the WHO, and is the leading cause of death in dozens of countries.

But people with cancer are surviving longer. In high-income countries, five-year net survival rates for breast and prostate cancer are around 80% to 90%, according to the report.

Emil Lou, an oncologist and associate professor of medicine at the University of Minnesota, told The Washington Post that improvements in cancer surveillance and treatments such as immunotherapy have greatly increased patient survivability.

“While we’ve made great progress as a society in treating some forms of cancer more effectively than ever before, the rise in cancer prevalence worldwide reminds us that we still have a very long way to go,” said Lou, who was not involved in the WHO study.

The WHO report highlighted steep differences in cancer outcomes for lower-income regions lacking access to better cancer treatment and surveillance.

In high-income countries, the five-year net survival rate for breast cancer exceeds 85%, according to the WHO; in low-income countries, it drops below 30%.

Isabelle Soerjomataram, an epidemiologist with the International Agency for Research on Cancer who also spoke at the WHO news conference, said cervical cancer has been reduced to “almost elimination” in parts of Europe and North America.

“In many countries of sub-Saharan Africa, it is still the top, number one cancer,” she added.

Countries both rich and poor are not adequately investing in programs for cancer prevention and treatment, the report said, though it highlighted moderate progress in curbing some practices and conditions that can cause cancer.

The report praised global progress in adopting measures to reduce tobacco use, which has dropped 27% since 2010. Separately, 85% of countries now include human papillomavirus vaccines in their national vaccine programs, according to the report, and an estimated 31% of girls have received the first dose of the vaccine, up from 17% in 2019.

Among the most alarming trends highlighted in the report was a failure by most countries to curb rising obesity rates. Obesity has been linked to more than a dozen cancers, including liver, pancreatic and colorectal cancer, according to the NIH.

“It will be a significant added burden for every country globally when cancers associated with obesity become the norm,” Ilbawi said. “That will likely happen in a significant number of countries in the next 20 or 30 years.”

Soerjomataram said that while the report’s projections for future cancer cases may be alarming, many of them are preventable.

“Four in 10 new cancer cases are linked to risk factors … we already know how to address,” Soerjomataram said.