By Amy Norton
FRIDAY, January 31, 2020 (HealthDay News) – A new study finds that the rate of colon cancer among Americans increases dramatically between the ages of 49 and 50, which supports the case of earlier detection of the disease.
The researchers say that the increase between these two ages does not reflect a real increase in the onset of colon cancer, but the fact that the detection of the disease has traditionally begun at age 50. Then, "latent" cancers that had been present for some time are detected at that age.
Experts said the findings could have implications for colon cancer screening recommendations, which are currently contradictory.
For years, the guidelines of several groups said that people at average risk of colon cancer should begin to be screened at age 50. The previous evaluation was reserved for people at higher risk.
But in 2018, the American Cancer Society lowered its recommended threshold at age 45, largely due to a rising incidence of colon cancer among younger Americans.
But the US Preventive Services Working Group. UU., Which sets the federal detection standards, still recommends an initial age of 50 years for people with average risk.
Given the debate, Dr. Jordan Karlitz said his team wanted to observe more closely how colon cancer rates in Americans change in annual age increases. Previous studies, he explained, have analyzed age blockages, such as 45 to 49 and 50 to 54.
A look year after year, Karlitz said, could give a clearer picture of what is happening among people in their 40s. It has long been suspected that the incidence of colon cancer in that age range is higher than the statistics show, because most people between 40 and 40 do not have screening tests.
The researchers expected to see an increase in colon cancer between the ages of 49 and 50. What they found was an increase of 46%.
"It was a strong rebound," said Karlitz, an associate clinical professor at the Tulane University School of Medicine in New Orleans. "We expected to see something, but not to that extent."
The pattern probably reflects cancers that began before age 50, even years before, but were not detected until detection began, according to Dr. Umut Sarpel.
Sarpel, who was not involved in the study, is an associate professor of surgical oncology at the Icahn School of Medicine at Mount Sinai in New York City.
"The results of this study support efforts to reduce the detection age to less than 50 years," said Sarpel.
The findings, published online on January 31 in JAMA Network Open, are based on government data on cancer from 2000 to 2015. The Karlitz team focused on colon and rectal cancer rates among young people aged 30 to 60.
During that period, the rate among 49-year-old Americans was less than 35 cases per 100,000 people. The researchers found that that increased to 51 cases per 100,000 among 50-year-olds.
The vast majority of cases detected at age 50, almost 93%, were invasive, which means that they would probably require more extensive treatment and probably have been there for some time.
Statistics show that most colon cancers are diagnosed after age 50. However, the rate among younger Americans has been rising, for reasons that are not yet clear.
A study by the American Cancer Society found that since the mid-1990s, colon cancer rates among Americans aged 20 to 54 have increased steadily, between 0.5% and 2% each year. Rectal cancer has increased faster, from 2% to 3% per year.
"It has been known for about 15 years that rates of colon and rectal cancer are increasing among young patients," said Dr. Joshua Meyer, a radiologist oncologist at the Fox Chase Cancer Center in Philadelphia. "This seems to be true for both those under 40 and between 40 and 50 years."
What is not clear, Meyer said, is how long colon tumors can be growing when they are finally detected through detection.
"This study makes it clear that they have been growing for several years," said Meyer, who was not involved in the research.
The increase between the ages of 49 and 50 was observed not only for cancers confined to the colon and rectum, but also for regional cancers, which means that the disease has spread to nearby lymph nodes. There was also a small increase (just under 16%) in more advanced cancers, those that have spread to distant sites in the body.
Meyer said it is worrisome to see an increase in more advanced cancers. The findings support the "consideration of reducing the age of detection for colorectal cancer," he said.
Researcher Karlitz said he hopes the results "shed light" on the fact that colon cancer is more common among people in their 40s than statistics suggest.
For now, he said people should discuss the best screening strategy, including the age of onset, with their doctor. And everyone, no matter how young they are, must act on the possible symptoms of cancer, Karlitz emphasized.
Some possible warning signs include a persistent change in bowel habits; abdominal pain or cramps; dark stools or with visible blood; and involuntary weight loss.