YOUNG RECTAL CANCER-WOMEN AND WHITE

Rates of rectal cancer are increasing in young people, and those affected are overwhelmingly female and white, new research indicates.

The work shows an annual increase in rates of the malignancy in people younger than 50 years of about 3%.

"At this point, we can't figure out what's causing these numbers to continue going up," said investigator Odinaka Mogor, MS, a fourth-year medical student at the University of Arizona in Tucson.

"We already know there's a family history component, and other factors, such as alcohol use and obesity," also contribute, Mogor told Medscape Medical News. "The next step is looking at molecular pathways. We want to know on a molecular level if there's something we can isolate to help us reverse this trend."

This finding intensifies focus on the rising colorectal cancer rates in younger age groups. Although colorectal cancer rates have declined overall in the past few decades, 30% of cases are now diagnosed in people younger than 55 years, according to 2017 data from the American Cancer Society, as reported by Medscape Medical News.

Just last week, the society updated its guidelines and now recommends that colorectal cancer screening begin at age 45, rather than age 50, as reported by Medscape Medical News.

Cancer Screen Before Age 50

The investigators wanted to isolate factors correlated with the upward trend in rectal cancer at younger ages, Mogor explained here at Digestive Disease Week 2018.

For their study, he and his colleagues analyzed data on 68,699 patients with rectal cancer from the 2010 to 2012 National Inpatient Sample database.

During that 3-year period, 2748 (4%) of the cases diagnosed were in people younger than 50 years. But in that younger age group, the incidence rose over each of the 3 years, by 2.8%, 3.0%, and 3.4%.

Notably, the younger people diagnosed with rectal cancer were more likely to be women than men (62% vs 39%). More research is needed to discern the reason for this, Mogor pointed out.

"It might be related to hormonal issues," he said. "We don't know quite yet. This is in contrast to what we see in older populations, where men are affected more."

Most doctors are not expecting rectal cancer, so they're treating it as IBS or something else.

Younger patients diagnosed with rectal cancer were more likely than older patients to be white (71% vs 42%). And patients younger than 50 years were far more likely to have a family history of rectal or colon cancer than older patients (48% vs 18%), and were more likely to be obese and to use alcohol.

Younger patients were also more likely to be diagnosed at a more advanced stage of rectal cancer because of misdiagnosis.

"The symptoms are well known, but we expect to see this in a population over age 50," he said. "As it's presenting in younger and younger age groups, most doctors are not expecting rectal cancer, so they're treating it as IBS or something else."

The strong research focus on the incidence of colorectal cancer in younger age groups is reassuring, said Volkan Taskin, MD, from the University of Maryland in Easton.

Although he said he hasn't noticed a similar trend in his own practice, "this helps me out a lot," he told Medscape Medical News. "It's more on my radar and I will be vigilant."

James Walter, MD, from the Einstein Medical Center in Philadelphia, also said he is not seeing a rising number of younger rectal cancer patients in his practice, but his colleagues have reported that they are.

"It's scary. It's changing my practice," Walter told Medscape Medical News. "Three or 4 years ago, I would have chalked [rectal cancer symptoms in young adults] up to other things. I'm more proactive with how I manage these patients now."

Mogor, Taskin, and Walter have disclosed no relevant financial relationships.

Digestive Disease Week (DDW) 2018: Abstract Tu1682. Presented June 5, 2018.