Healthcare providers are seeing increasing numbers of younger patients with colorectal cancer, and they’re being diagnosed with more advanced stages of the disease, researchers reported in study findings published in the journal Cancer.

Using data from the National Cancer Data Base, the researchers compared colorectal cancer diagnoses from 2004–2013 in 130,165 patients younger than 50 years and 1,055,598 patients aged 50 and older. Diagnosis rates in younger patients rose from 10% in 2004 to 12.2% in 2013, and nearly 52% were advanced disease, compared to 40% in patients aged 50 and older. Demographically, the increases skewed toward female, African American, and Hispanic younger patients, as well as those who live in urban areas or had higher incomes.

The researchers said that the cause for the increase was unclear, but they called for stricter adherence to screening guidelines. “Many guidelines recommend screening at age 45, but most physicians and patients don’t appear to be following those recommendations,” they said.