Haven’t Heard of Lynch Syndrome? You’re Not Alone.

But because it can raise your risk for cancer, knowing if it's in your family and getting annual check-ups could save your life.

By Chad Burns | UCSF.edu | March 19, 2026

An illustration of a gloved hand holding a petri dish under a microscope, where a glowing yellow immune cell targets several red, spiky cancer cells.

When Allen Rush learned he carried the genetic mutation known as Lynch syndrome, he understood what was at stake.

Years earlier, his daughter Jacqueline was diagnosed with colorectal cancer at age 20, as a result of Lynch. She died three years later. Rush did not know about Lynch syndrome even though his father passed away from colorectal cancer many years before, when he was in his mid-fifties.

Lynch syndrome affects about 1 in 279 people in the U.S. and significantly increases the lifetime risk of colorectal cancer and several other cancers. An estimated 95% of people with Lynch syndrome do not know they carry the mutation.

“Colorectal cancer is one of the cancers that if you catch it early it can be easily treated— or even screened early enough, you can prevent it,” Rush said. “Had we known about Lynch syndrome before, none of this would have happened.”

Today, Rush undergoes annual colonoscopies at UCSF and is participating in a National Institutes of Health (NIH)–sponsored clinical trial designed to prevent cancer in people with Lynch syndrome.

UCSF is the only site in California participating in the randomized, placebo-controlled vaccine study.

“This is a true cancer prevention trial,” said Aparajita Singh, MD, director of the UCSF Lynch Syndrome Center. “Patients are receiving a vaccine to see if we can activate immune cells to eliminate cancer cells as they are forming.”

Read more at UCSF.edu