Invasive colorectal cancers by age 50 bolster case for earlier screening

Last Updated: 2020-01-31

By Linda Carroll

(Reuters Health) - The vast majority of colorectal cancers detected in 50-year-olds - when screening usually begins - turn out to be invasive, suggesting screening should start earlier, researchers say.

Earlier screening might catch many cancers in time to avoid surgery, the study team concludes in JAMA Network Open.

After analyzing data from more than 165,000 colorectal cancer patients who were diagnosed between 2000 and 2015, researchers determined that nearly 93% of the cancers were no longer in situ.

In contrast to previous studies that grouped patients in multi-year age blocks, such as 45-50, the new study looked at cancer cases diagnosed in one-year age increments. With that kind of detailed examination, the researchers were able to bolster the case for starting screening earlier than age 50.

"Most colorectal cancers take several years to grow," said study coauthor Dr. Jordan Karlitz, an associate professor at Tulane University School of Medicine in New Orleans and a staff gastroenterologist at the Southeast Louisiana Veterans Health Care System. "What we are seeing at age 50 started years before but wasn't detected before then. So it was probably present in the mid-to-late 40s."

The American Cancer Society recommends screening start at age 45, but other medical groups still suggest screening begin at age 50, Karlitz said.

To take a closer look at what was happening between the ages of 49 and 50, Karlitz and his colleagues turned to the Surveillance, Epidemiology, and End Results database, which represents 28% of the U.S. population.

The researchers chose to look at the years 2000 to 2015 because it was during those years that screening for colorectal cancer became commonplace.

Cancers in 50-year-olds were presumed to have been detected as a result of screening, while those diagnosed in younger patients were assumed to have been discovered because patients were symptomatic or because they had a family history of the disease.

Out of a total of 9,474 cancers detected in 50-year-olds, 8,799 were invasive.

Karlitz noted that the rate of colorectal cancers in people younger than 45 are on the rise. "So an important take-home message is that even if you're really young - in your 20s or 30s - you should get a prompt and thorough evaluation if you have a family history or start to have symptoms," he said, adding that telltale symptoms can include a change in bowel habits, rectal bleeding and abdominal discomfort.

The new study along with other recent research supports lowering the screening age from 50 to 45, said Dr. Otis Brawley, the Michael Bloomberg Professor of Oncology and Epidemiology at Johns Hopkins Medicine in Baltimore.

Another issue, Brawley said, is what screening tests should be used. "Most of us who do screening are not as married to colonoscopy as the general public is," Brawley said. "An alternative is the (fecal immunochemical test), which can cost $30. And other than handling the stool, it's not very inconvenient. A colonoscopy costs about $3,000 and requires several days of preparation and, for most people nowadays, anesthesia."

Another option, Brawley said, is the virtual colonoscopy, which is accomplished via a CT scan. One advantage of the virtual colonoscopy is that the doctor can easily go back and have a second look at something she's not sure of.

The new study is "important," said Dr. Edward Chu, deputy director of the UPMC Hillman Cancer Center and a professor and chief of the division of hematology and oncology at the University of Pittsburgh School of Medicine.

"It provides further support that starting screening at age 45 is the right thing to do," Chu said. "And I wouldn't be surprised if the age went even further down."

That's because colorectal cancer appears to be striking an increasing number of younger people, Chu said.

SOURCE: https://bit.ly/2UcShlR JAMA Network Open, online January 31, 2020.