Rates of colon and rectal cancer are rising rapidly for young people – between 1991 and 2014, rectal cancer rates doubled for people between the ages of 20 and 49 years. According to one analysis, someone born around 1990 is twice as likely to have colon cancer as a person born in 1950 and four times more likely to develop rectal cancer.
This spike has led the American Cancer Society (ACS) to recommend that people with colorectal cancer screening – a term commonly used to describe colon and rectal cancer – age 45 instead of 50, the company announced on Wednesday.
Colorectal cancer is the fourth most common cancer diagnosed in adults and the second most common cause of cancer deaths, just behind lung cancer.
For decades, death rates from colorectal cancer declined in patients 55 years of age. This change was attributed to healthy lifestyle changes and broader screening. But in recent years, colon and especially rectal cancer rates have started to rise under a younger demographic. And researchers do not know why it happens.
A Quest for Explanations
It is noteworthy that case numbers for people between the ages of 20 and 49 are still not high ̵
As the ACS researchers stated in the publication of the new screening guidelines, the increase in colorectal and rectal cancer cases can not be explained simply by the fact that screening is more frequent and more cases are found. People in this younger age group are not often screened and the mortality rate of young people is also increasing.
A study in the Journal of the National Cancer Institute, discussing changing rates of illness, found that young people suffering from these cancers are healthier in many ways than before. They drink and smoke less, but they have higher rates of obesity, which increases the risk of colorectal cancer.
The authors also believe diet could play a role, with a low-fat, low-fiber diet in the Western style increasing cancer risks. But there may be other, unknown, explanations.
Different Types of Screenings – It's Not Just a Colonoscopy
Catching the colon and rectally early can make a big difference because precancerous polyps – abnormal growths in the colon or rectum – can be removed become. With early detection, these cancers have high cure rates.
But about a third of over-50s are never screened.
ACS's new guidelines suggest that all healthy adults (men and women) aged 45 and over 50 should be screened for colorectal and rectal cancer for at least 75 years. For patients aged 76 to 85 years ACS says that physicians and patients should decide on a case-by-case basis whether it makes sense to continue the screening based on life expectancy and preference. For patients over the age of 86 years, ACS advises against screening.
Screening for colon or rectal carcinoma is not always a colonoscopy, although this is usually required if another type of test indicates a problem.
There are six tests proposed by the ACS as options for screening. Annual testing options include two types that can be performed from home – for which patients collect a stool sample and send it in for testing. (The scientific names for these tests are a fecal immunochemical test and a highly sensitive, guaiac-based fecal occult blood test.)
Another option is a multi-target stool DNA test, performed every three years And collecting also includes a sample at home and send them in. Every five years, a person could do a computed tomography colonoscopy test (a scan like a CAT scan) or a flexible sigmoidoscopy scan (essentially a tube with a light and camera).
A colonoscopy is recommended every 10 years.
The ACS did not recommend a specific test because a general recommendation for screening with different options is more likely.
The US Preventative Services Task Force – an independent expert panel that publishes recommendations on medical care services such as screenings – has previously found that there are strengths and weaknesses in various tests. But overall, the review with one of these tests reduced mortality rates from colon and rectal cancer compared to not screened.
According to ACS, there is still a "strong recommendation" that adults start screening at the age of 50 – this phrase means that there is good evidence that this the mortality lowers rates.
The recommendation that people over 45 should be screened is referred to by the ACS as a "qualified recommendation". This means that researchers need more data on the impact of early detection of people at these ages to better understand how the practice affects the diagnosis of colorectal cancer and patients. Based on the way in which colon and rectal cancer affects younger people, the ACS has found that such a change is still important to recommend.
For now, the recommendations of the US Preventative Services Task Force strongly recommend that people age 50 start screening.
When younger patients are screened, there will be more data on how this affects the colorectal cancer rate. If current trends continue and more and more young people are developing these forms of cancer, it is possible that some researchers might suggest that screening be even younger.