Microplastics, Diet and More: What’s Causing Early-Onset Cancer?

According to the American Cancer Society, the overall cancer mortality rate in the United States has declined by 34% since 1991. However, the incidence of early-onset cancer, which refers to cancer diagnosed in adults younger than 50 years, is on the rise. Could this surge jeopardize previously gained ground?

In a February 2025 Time magazine cover story, Jamie Ducharme reports on this atypical and disquieting trend. To be sure, cancer diagnoses in adults aged 50 and older still make up the majority (88%) of cases, but the rate of new incidences is increasing only in adults younger than 50. Ducharme cites a 79% increase in early-onset cancer diagnoses and a 28% increase in cancer-related deaths in this age group from 1990 to 2019.

Young woman with cancer in a headscarf.

This concern was echoed in a February 2024 conversation Managed Healthcare Executive editors had with Sanjula Jain, Ph.D., chief research officer at Trilliant Health. She shared findings from a Trilliant survey highlighting the concerning rise in cancer cases among those in their 30s and 40s, despite declining mortality rates overall.

"For the first time in our history, we're seeing more deaths attributed to neoplasms in the 35- to 44-year-old population," Jain noted.

Between 2018 and 2022, there was about a 5% increase in deaths in this age group, all the while mortality rates for older populations—those aged 45 to 64—continued to decline.

So, what gives? What is causing the increase among younger populations? Researchers are not entirely sure, and the answer is likely complex and multifactorial. Some scientists have theorized culprits, such as the ubiquity of microplastics or the abundance of ultra-processed foods.

Research at Brigham and Women’s Hospital in Boston points to risk factors, such as consuming a diet high in sugar and processed foods and low in fresh fruits and vegetables, developing insulin resistance, and having an E. coli strain in the gut. However, there are still no concrete answers.

Not every type of early-onset cancer is on the rise. Many oncologists are seeing an increase in digestive system cancers, such as stomach, pancreatic, or colorectal, in young adults. On the other hand, lymphoid leukemia and non-Hodgkin lymphoma incidence rates have been increasing by a slim 0.7% per year in adolescents ages 15 to 19 years, and the rates have declined by 0.8% per year in children younger than 15.

Notably, improvements in diagnostic techniques inevitably lead to more diagnoses and earlier detection, but scientists believe that is only part of the puzzle. Research is ongoing at Memorial Sloan Kettering Cancer Center in New York City, Brigham and Women’s Hospital, and other cancer centers to identify risk factors and discover ways to reverse the rising trend of early-onset cancer.

Meanwhile, early-onset cancer centers are developing or expanding programs that address issues unique to young adults experiencing cancer diagnoses. These can range from the impact of the disease on work and social life to sexual health and fertility preservation.

In addition, Jain expressed that the healthcare industry must reconsider how it engages with younger populations, especially given the ongoing decline in primary care visits.

“Primary care engagement in the U.S. is still down about 8.4% from 2018 to 2022, despite increased accessibility through virtual care and retail clinics,” she noted in the February 2024 interview.

As researchers continue to explore potential links and risk factors, experts urge younger adults to prioritize preventative care, maintain a healthy lifestyle and take advantage of routine screenings to help detect cancer at earlier stages.