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Colon cancer, a disease usually associated with middle age and the elderly, is showing up in younger Americans, new research shows.
It’s not an alarming number yet, and doesn’t mean that people under 50 need to start getting colonoscopies, doctors stressed. But the trend is troubling, and doctors may need to think colon cancer when younger people show up with symptoms.
“Particularly in people between ages 20 and 34, we estimate a doubling in incidence rate of colorectal cancer,” said Dr. George Chang of the MD Anderson Cancer Center, who led the study.
“Particularly in people between ages 20 and 34, we estimate a doubling in incidence rate of colorectal cancer."
Chang said he started the study after noticing he was operating on younger patients with colon cancer. Many didn’t have a family history of the disease, which troubled him. People with an inherited genetic tendency to cancer can develop tumors young, but it’s less common without a DNA mutation.
“My impression is that we have been seeing more young people today than we saw a decade ago,” Chang told NBC News. “We did our study using population data to confirm if what we were seeing in our own hospital was true for the country as a whole.”
They looked at 393,000 patients diagnosed with colon cancer between 1975 and 2010.
The numbers confirm what other experts have seen — colon cancer rates are going down steadily in the population as a whole. Colonoscopies are responsible for a lot of this, as they allow doctors to remove pre-cancerous growths called polyps before they can ever become cancer.
But there was an increase in people under 50. Colon cancer rates rose by nearly 2 percent among people aged 20 to 34 over that time.
If the trends continue, they report in the journal JAMA Surgery, the number of colon cancer cases in people aged 20 to 34 will spike by nearly 40 percent by 2020 and 90 percent by 2030.
“We’re talking small numbers, but they’re important numbers when we talk about them possibly increasing over time,” Chang said.
“In absolute terms, we may end up with numbers that no longer will seem so small."
Colon cancer is a big killer — the No. 3 cause of cancer death in the United States. More than 140,000 people will be diagnosed with colon cancer this year and 50,000 will die of it. The numbers for people under 40 are very small, however. About 3,600 people under 40 get colon cancer every year and just 750 people under 30.
But those numbers can add up, said Chang.
“In absolute terms, we may end up with numbers that no longer will seem so small,” he said. “I wouldn’t go ringing the fire bells today based on these small numbers but it’s something we should be aware of."
What’s causing the increase is not clear, but several cancer experts noted that colon cancer is often caused by diet and a lack of exercise.
“Clearly, lifestyle factors impact colorectal incidence,” said Dr. Len Lichtenfeld of the American Cancer Society.
“We can’t say for certain if that’s what’s causing this increase, and which lifestyle factor is responsible based on this study, but we do know there’s been a fundamental change in our behaviors, and we have to pay attention to these factors."
Chang said doctors should not rule out colon cancer in young people with symptoms.
“We need to make sure we’re all thinking about colorectal cancer as a potential problem so that when a younger patient presents with symptoms we don’t discount the possibility of colorectal cancer,” he said.
“There’s been a number of national initiatives to improve diet and lifestyle, and we need to promote those efforts. That is the low-hanging fruit, this is not strictly a colorectal phenomenon, we would probably observe similar findings with other cancers if we looked for it,” he added.