Compared with adults born circa 1950, those born circa 1990 have double the risk of colon cancer and quadruple the risk of rectal cancer.
That's according to a study published Feb. 28 in the Journal of the National Cancer Institute(academic.oup.com) that was spearheaded by scientists at the American Cancer Society (ACS).
The study found colorectal cancer (CRC) incidence to be rising in young and middle-aged adults, including people in their early 50s, with rectal cancer rates increasing particularly fast. As a result, three in 10 rectal cancer diagnoses are now in patients younger than 55.
"Trends in young people are a bellwether for the future disease burden," said Rebecca Siegel, M.P.H., strategic director of surveillance information services for the ACS, in a news release(pressroom.cancer.org). "Our finding that colorectal cancer risk for millennials has escalated back to the level of those born in the late 1800s is very sobering. Educational campaigns are needed to alert clinicians and the general public about this increase to help reduce delays in diagnosis, which are so prevalent in young people, but also to encourage healthier eating and more active lifestyles to try to reverse this trend."
- A study from the American Cancer Society (ACS) found colorectal cancer (CRC) incidence to be rising in young and middle-aged adults, including people in their early 50s.
- The good news out of this research is that overall CRC prevalence in the United States has declined since the mid-1980s, with the sharpest drops in incidence occurring within the past 10 years.
- ACS researchers based their findings on a retrospective cohort study of patients 20 and older who were diagnosed with invasive CRC from 1974 through 2013 in nine areas throughout the country.
The good news to come out of this research is that overall CRC prevalence in the United States has declined since the mid-1980s, with the sharpest drops in incidence occurring within the past 10 years.
Family physician Richard Wender, M.D., chief cancer control officer for the ACS and chair of the National Colorectal Cancer Roundtable, told AAFP News that without question, this decrease in CRC rates is related to the advent of fiber-optic scoping and polyp removal.
"In the past 20 years, we've been systematically screening for colon cancer," he said. "In fact, screening rates are increasing. When we find and remove polyps, we prevent colon cancer. That is the key factor."
Additionally, the study's authors noted that because of this surge in CRC rates in younger adults, it might make sense to reassess the age range for recommended screening. The ACS recommends beginning screening at age 50. The AAFP and U.S. Preventive Services Task Force similarly recommend screening for CRC in adults ages 50-75.
ACS researchers said in 2013, 10,400 new cases of CRC were diagnosed in patients in their 40s and 12,800 cases in patients in their early 50s.
"These numbers are similar to the total number of cervical cancers diagnosed, for which we recommend screening for the 95 million women ages 21 to 65 years," Siegel said.
Wender said the new ACS data should be considered during all future CRC guideline updates.
'80% by 2018' Update
Back in 2014, the AAFP joined more than 1,300 other organizations in supporting the "80% by 2018" initiative(nccrt.org), which was created by the National Colorectal Cancer Roundtable (NCCRT) with the goal of increasing the percentage of adults 50 and older who get screened for colorectal cancer (CRC) to 80 percent by 2018.
Family physician Richard Wender, M.D., chair of the NCCRT and chief cancer control officer for the American Cancer Society, told AAFP News the campaign is working.
"CRC screening rates are going up since we launched 80 by 18!" he said. "We can reach this goal -- but only if family physicians lead the way."
"Deciding which age to start screening is never straightforward," he said. "We have to be sure that these early onset cancers are similar enough to the cancers that occur after age 50 that screening will work. And both the potential risks and benefits of screening will have to be considered."
ACS authors based their findings on a retrospective cohort study of patients 20 and older who were diagnosed with invasive CRC from 1974 through 2013 in the nine oldest Surveillance, Epidemiology and End Results program areas: Atlanta, Connecticut, Detroit, Hawaii, Iowa, New Mexico, Seattle-Puget Sound, San Francisco-Oakland, and Utah. The analysis included more than 490,000 cases.
The study found that after having decreased since 1974, colon cancer incidence in adults 20-39 started to increase from the mid-1980s through 2013 by 1 percent to 2 percent per year. In patients 40-54, rates increased by 0.5 percent to 1 percent per year from the mid-1990s through 2013.
Even more alarming, rectal cancer incidence has been increasing more quickly, and for longer, than that for colon cancer -- rising about 3 percent per year from 1974 through 2013 in adults 20-29 and from 1980 through 2013 in patients 30-39. In adults 40-54, rectal cancer rates have increased by about 2 percent per year from 1990 through 2013.
In contrast, rectal cancer rates in adults age 55 and older generally declined during the entire 40-year study period, including well before widespread screening was common practice.
These opposing trends have narrowed a previously sizeable disease risk gap between adults 50-54 and those 55-59. In the 1990s, both colon cancer and rectal cancer rates in adults 50-54 were half of those in adults 55-59. But from 2012-2013, the comparative rates were just 12.4 percent lower for colon cancer and equal for rectal cancer.
Possible Causes of Spike in CRC Rates
Wender said the cause of the marked increases in the risk for colon and, particularly, for rectal cancer in each succeeding generation since 1950 is unknown.
"Given the rapidity of this change, it's unlikely that this represents a change in genetically inherited cancers," he said. "It's far more likely that this is related to external factors. The leading candidates are changes in our diet and physical activity level."
Wender added that obesity is a known risk factor for CRC, but this spike could be related to patients' increased intake of simple sugars or even a reduction in routine use of aspirin or other nonsteroidal anti-inflammatory drugs.
Furthermore, changes in the microbiome -- possibly due to increased antibiotic use and dietary changes -- should be considered, he said.
Infectious diseases such as HPV may also play a role. It's widely known that the HPV vaccine helps prevent cervical cancer, but Wender said he's optimistic that it also would help prevent other HPV-related cancers including head and neck, anal, and some rectal cancers.
Because of the variety of these possible causes of CRC, Wender said it's important to conduct more research that focuses on the sources of this growing health concern.
Calling All Family Physicians
Colon cancer can occur at any age. That's why Wender said family physicians should never dismiss rectal bleeding, changes in bowel habits or unexplained iron deficiency. Patients with these symptoms need to be fully evaluated.
Wender also said efforts to gather complete family histories and periodically update them must improve.
"Anyone with a first-degree relative with a history of colon cancer or a colon polyp is not at average risk and should begin screening before age 50," he said.
CRC is the second leading cause of cancer-related death in adult patients, yet it can be prevented completely or found early when it's still fully curable through screening. The good news, according to Wender, is there are several highly effective screening tests available to facilitate this.
"Colonoscopy every 10 years is a great test, but there are also simple, affordable tests that can be done in the privacy of your own home," he said. One such test, a novel stool-based colorectal screening test that detects red blood cells and DNA mutations, was approved in 2014.
Wender cautioned that if family physicians fail to recommend screening for CRC to patients, the likelihood that patients will ever be screened plummets.
"Of all the preventive interventions in your practice, very few are as reliably life-saving as CRC screening," he said. "Major quality improvement programs and pay-for-performance program measures hold family physicians accountable to increase CRC screening rates. We're relying on you to increase these rates."
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