Understanding the Rise in Early-Onset Cancers

In the 1930s, the state of Connecticut created the world’s first cancer registry: a database that tracks statistics about cancer diagnoses and outcomes in a certain area. Today, there are cancer registries across the United States and the world to help researchers access key information, including who’s at risk for certain cancers, how patterns in cancer diagnoses change over time, whether treatment and prevention measures are working, and any new trends that should be studied.

Using these records, researchers have found that early-onset cancers, which occur before age 50 (or age 40 for breast cancer), have been on the rise. One study found that from 1990 to 2019, early-onset cancer rates increased nearly 80% worldwide.

Columbia researchers Mary Beth Terry, PhD, and Rebecca Kehm, PhD, MPH, who study cancer risk and prevention, break down these trends and discuss what young people should know.

Which early-onset cancers are becoming more common?

Early-onset breast cancer diagnoses have been rising globally since they were first recorded in Connecticut nearly 100 years ago, and the numbers continue to grow. Drs. Terry and Kehm recently found that rates of early-onset breast cancer in the U.S. are substantially higher than those of other early-onset cancers. Their research has also demonstrated geographic differences within the U.S., highlighting how environmental, social, and regional factors may shape early-onset cancer risk.

“Breast cancer is by far the most common type of cancer in adults under 40,” says Dr. Kehm. “Even though it primarily affects women, the number of breast cancer cases is greater than colorectal cancer cases in men and women combined. It’s an overwhelming burden when we think about the types of cancer that are affecting younger adults.”

A more recent trend is the rise in early-onset thyroid and colon cancer rates, which have been increasing in both men and women since the 1990s.

Early-onset breast and colorectal cancers tend to be aggressive and advanced by the time they’re diagnosed. Most routine preventative screenings like mammograms and colonoscopies don’t begin until later in life, so when a young adult has cancer, it’s usually found when they experience symptoms, which can happen months or years after the cancer starts growing.

Why are more young people getting cancer?

Smoking, alcohol use, and genetics are linked to breast and colon cancer, but oncologists have been seeing more young patients with cancer who don’t have any of these risk factors.

“The data are suggesting that cancer rates are increasing with each birth cohort. For example, Gen Z is having more cancer diagnoses than Gen X at an earlier age, and it’s happening worldwide, including in countries where women don’t drink alcohol,” says Dr. Terry.

Researchers believe environmental factors like exposure to forever chemicals and microplastics play an important role in breast and colon cancers, though there are likely many factors that contribute. “While people with a family history or genetic predisposition might be more likely to be diagnosed with cancer at a younger age, we're finding that across the board, anyone could be at risk,” says Dr. Kehm.

How can young adults lower their risk of cancer?

Lifestyle factors like reducing alcohol intake, maintaining a healthy weight, and exercising can help minimize the risk of developing breast and colon cancer. You can reduce your exposure to forever chemicals by storing food in glass containers instead of plastic and using cleaning products with natural ingredients.

It’s important to seek medical care if you notice changes in your breasts or have gastrointestinal symptoms, no matter how old you are.

“No one is too young to get cancer, but it’s still rare,” says Dr. Kehm. “Understanding what populations are at higher risk and why can inform clinical approaches and public health policies to help reduce the burden.”

Mary Beth Terry, PhD, is a professor of epidemiology in environmental sciences at the Columbia University Mailman School of Public Health and the associate director for Population Sciences and Community Outreach at the Herbert Irving Comprehensive Cancer Center. She is also the executive director of the Silent Spring Institute.

Rebecca Kehm, PhD, MPH, is an assistant professor of epidemiology at the Mailman School of Public Health and member of the Cancer Population Science program at the Herbert Irving Comprehensive Cancer Center.