The study also found that former smokers were nearly twice as likely to develop early-onset colorectal cancer compared to nonsmokers.

When it came to colonoscopies, symptoms were the main motivator: 88% of those diagnosed underwent the procedure due to issues like bleeding, compared with just over half of cancer-free patients.

The findings were presented at the American College of Surgeons Clinical Congress 2025.

A Growing Crisis Among Young Americans

Colorectal cancer rates are climbing among younger adults. According to the Cancer Research Institute, one in five new cases now occurs in people under 55 — a dramatic rise that has been building since the 1990s, even as older adult cases decline.

The causes remain uncertain, but researchers believe modern lifestyles are largely to blame — including sedentary routines, obesity, and diets high in processed foods. Environmental pollutants in air, water, and soil are also suspected contributors.

Because symptoms in younger patients are often dismissed or misdiagnosed, many are diagnosed at later stages — when treatment options are more limited.

Today, colorectal cancer stands as the leading cause of cancer death in American men under 50, and the second deadliest for women in the same age group. In 2023 alone, the disease claimed the lives of 3,750 young adults and affected nearly 20,000 others, according to the American Cancer Society.