It’s a mystery doctors and scientists have yet to solve: More younger adults are getting diagnosed with cancer.

The number of early onset cancer cases — those that occur in adults under age 50 — is rising by 1% to 2% annually, according to the American Cancer Society.

An analysis of global health data published in the journal BMJ Oncology predicts a 30% jump in early onset cancers between 2019 and 2030.

This story appeared in The Forefront magazine. Read the Summer 2024 issue.

Meanwhile, celebrity cancer cases — including actor Chadwick Boseman’s death from colon cancer at age 43, or the cancer diagnosis at 42 of Catherine, Princess of Wales — have put a spotlight on young people facing the disease.

Oncologists at the University of Chicago Medicine Comprehensive Cancer Center say they’re seeing the increase firsthand, and that they are treating more patients in their 30s and 40s in many cancers, including breast, colorectal, and head and neck cancers.

What factors are causing cancer in young people?

Scientists and researchers are still searching for a specific culprit.

“We have yet to identify any singular reason, although it’s likely related to a multitude of factors — possibly including lifestyle or environmental ones,” said UChicago Medicine adult and pediatric oncologist Adam DuVall, MD, MPH.

Some possible reasons include:

• Chronic inflammation: The body’s response to injuries and “invaders” can be caused by low physical activity, obesity, chronic stress, prolonged infections or chronic exposure to toxins.
• Later-in-life birth and/or having fewer children: Reproductive factors can lead to a slightly higher breast, ovarian or endometrial cancer risk.
• Gut microbiome changes: When this delicate network of bacteria is thrown off balance — possibly by processed foods, microplastics or other substances — it could be easier for tumors to grow.
• Healthcare disparities: Inequities in care can limit access to healthy food and timely treatment.

Cancer screenings by age

Young people diagnosed with cancer often fall below the minimum recommended age for screenings that can catch their disease early, said UChicago Medicine gynecologic oncologist Nita Karnik Lee, MD, MPH.

That’s why keeping tabs on your health — including any abnormal symptoms — and knowing your family’s history of cancer are critical details to share with your doctor.

Lee said people of all ages should never hesitate to see their doctor if there’s a concern about cancer. Taking early action can help ensure prompt, appropriate care.

“It’s important to identify those warning symptoms and give them attention as soon as possible,” Lee said. “If you have a family history of cancer, you may need to get screened sooner. We want patients to advocate for themselves.”