Dennis Massimo was informed in April 2025 that he carried a mutation in the MSH2 gene, after Penn Medicine BioBank researchers contacted him. The finding came from a blood sample he had provided nine years earlier, at the encouragement of his sister Lauren Massimo, an associate professor at Penn.
Lauren, who works in Nursing and Neurology at the University of Pennsylvania and co-directs the Frontotemporal Degeneration Center, often guides her family’s health decisions. She recalled urging Dennis to participate in the BioBank when he underwent a tonsillectomy in 2016.
Dennis, now 42 and living in West Chester, Pennsylvania, said he initially ignored repeated calls from the BioBank because he did not remember signing up. He eventually answered on April 14 and learned about the genetic mutation.
The research team explained that Dennis needed a clinical diagnostic test to confirm the finding since it originated from a research sample. They introduced him to Jessica Long, a genetic counselor at Penn Medicine specializing in hereditary cancer syndromes.
Long explained that mutations in MSH2 disrupt DNA mismatch repair functions, increasing cancer risk. Lynch syndrome is caused by mutations affecting one of four mismatch repair genes—including MSH2—and is the most common cause of hereditary colorectal cancer in the United States. About 1.2 million Americans are affected by Lynch syndrome. Individuals with an MSH2 mutation face a lifetime colorectal cancer risk between 30% and 50%, much higher than the general population’s risk of less than 5%.
At age 42, Dennis was younger than the recommended age for standard colonoscopy screening but received early screening due to his diagnosis. One month after learning about his genetic status, Dennis underwent his first colonoscopy.
He described waking up from the procedure: “The scariest part of the whole thing was waking up from the colonoscopy in a private recovery room, with a box of tissues next to me,” Dennis said. “I thought, ‘Oh my God, I’m in the grieving room.’”
Lauren was present when doctors informed them that Dennis had stage III colorectal cancer and would require surgery. She noted her brother had no symptoms: “Dennis had zero symptoms, and he was only 42—colorectal cancer was not on his radar,” Lauren said. “We thought he would get a baseline colonoscopy. We didn’t think they would find a tumor.”
Reflecting on his experience, Dennis said: “I found out when the cancer was stage III and not stage IV,” adding that participating in the BioBank may have saved his life.
