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Colorectal cancer is cancer that develops in the colon or rectum, which are parts of your large intestine. While colorectal cancer is often diagnosed in older adults, the number of younger adults being diagnosed with this cancer has been rising.

In this article we’ll explore what the research says about this trend, why young-onset colorectal cancer is on the rise, and the warning signs to look out for.

Colorectal cancer is still typically diagnosed in older adults. However, according to a report from the National Cancer Institute (NCI), there’s been a rise in colorectal cancer diagnoses in younger adults since the 1990s.

This trend is illustrated by a report from the American Cancer Society (ACS) in which it’s noted that the median age at diagnosis for colorectal cancer has shifted from 72 years of age in the early 2000s to 66 years of age in 2020.

The same report also estimated that almost 18,000 people in the United States, under the age of 50, would be diagnosed with colorectal cancer in 2020. This makes up about 12% of all new colorectal cancer diagnoses for that year.

In fact, another 2020 report on colorectal cancer trends found that the incidence of colorectal cancer in adults younger than 50 increased by 2.2% annually between the years of 2012 and 2016.

Meanwhile, the rate of colorectal cancer in adults older than 50 has been declining. This is likely due to regular colorectal cancer screening in this age group.

A large 2021 study found that, compared to people with older-onset colorectal cancer, those with young-onset colorectal cancer had improved survival, regardless of cancer stage. However, the ACS still estimated that there would be just over 3,600 deaths due to colorectal cancer in adults under age 50 in 2020.

It’s still unclear exactly why colorectal cancer rates are increasing in younger age groups. However, doctors and scientists do have some theories about this.

The NCI report above notes that there are some genetic conditions that increase the risk of young-onset colorectal cancer. However, only about 10% to 20% of young-onset colorectal cancers are caused by known genetic factors.

This suggests that other factors contribute to the rise in young-onset colorectal cancer. Indeed, a 2020 review notes that certain colorectal cancer risk factors related to environment and lifestyle are more prevalent in younger people now.

Some examples include having obesity, low physical activity, and an unhealthy diet. The research below illustrates how these factors affect colorectal cancer risk, particularly in younger age groups.

Colorectal cancer risk factors in younger adults

  • Having obesity: A 2019 study found that, while overweight women had an increased risk of young-onset colorectal cancer, having obesity nearly doubled a woman’s risk.
  • Eating an unhealthy diet: A 2022 review found that individuals who consumed large amounts of deep-fried, refined, high-fat, and sugary foods and beverages had a higher occurrence of early-onset colorectal cancer. The same study found that consuming more fruits and vegetables, and high amounts of micronutrients helped reduce the risk of colorectal cancer.
  • Engaging in low levels of physical activity: A 2018 study noted that increased TV time, a marker of a less active lifestyle, was also associated with a higher risk of young-onset colorectal cancer.
  • Changes to gut bacteria: Changes in the gut microbiome may also play a role. The types of bacteria present in your gut can be affected by your diet, weight, and activity levels. As already mentioned, these factors all play a role in your colorectal cancer risk.
  • Inflammation in the gut: Changes that favor some types of bacteria may also increase inflammation in the gut. This increase in inflammation may, in turn, raise the risk of cancer in the large intestine.

Gut inflammation is also why people with inflammatory bowel disease (IBD) have an elevated risk of colorectal cancer. In fact, people with colorectal cancer and IBD are about 15 years younger than people with colorectal cancer that don’t have IBD, according to the ACS.

Generally speaking, many of the risk factors for young-onset colorectal cancer are similar to those in older adults.

These risk factors can include:

How to reduce your risk of colorectal cancer

While not all colorectal cancers can be prevented, taking the following steps may help you reduce your risk of young-onset colorectal cancer:

  • Get moving: Try to prioritize physical activity by exercising for at least 30 minutes most days of the week.
  • Eat a healthy diet: Eat a balanced diet that focuses on fresh fruits and vegetables, whole grains, and lean protein sources.
  • Go easy with some types of meat: Try to reduce your intake of red meats and processed meats, like hot dogs, sausages, bacon, and lunch meats.
  • Manage your weight: If you carry excess weight, talk with your doctor about healthy ways to lose weight.
  • Limit alcohol consumption: Drink alcohol in moderation, or not at all.
  • Quit smoking: If you smoke, talk with your doctor about how to quit smoking.
  • Talk with your doctor: Talk with your doctor about any risk factors you may have for colorectal cancer and ask about your screening options.

There are several warning signs to be aware of with colorectal cancer, such as:

If you have any of these symptoms, regardless of your age, make an appointment with your doctor. They can screen you for colorectal cancer.

Even though colorectal cancer rates are on the rise among young adults, some medical professionals may still consider it to be an older person’s disease. Because of this, it’s possible that concerns about colorectal cancer may not be taken seriously.

In fact, some research has found that many younger adults have to make several appointments or need to see multiple doctors before receiving a diagnosis of colorectal cancer. Taking a longer time to diagnose any type of cancer can delay access to vital, life-saving treatments.

As such, it’s important to advocate for yourself if you’re concerned about young-onset colorectal cancer. You can do this by following the steps outline below.

  • Establish a relationship with a doctor whom you trust and feel comfortable with, and who listens to your concerns.
  • Learn as much as you can about colorectal cancer and its risk factors.
  • Find out if anyone in your immediate or extended family has been diagnosed with colorectal cancer.
  • Keep your own records of any concerning symptoms, how often they occur, and whether or not anything makes them better or worse.
  • Write down a list of questions to ask before seeing your doctor.
  • Have an open conversation with your doctor about your specific colorectal cancer risk factors and any screening recommendations.
  • Take careful notes during your appointments that you can reference later.
  • Ask additional questions when things are unclear or don’t make sense.
  • Speak up or push back if there’s something that you disagree with or are uncomfortable with.
  • Seek a second opinion, if necessary.

Over the past few decades, colorectal cancer has been on the rise among younger adults. Meanwhile, colorectal cancer diagnoses in older adults have been decreasing, likely due to regular cancer screenings in this age group.

Although it’s still not clear exactly why colorectal cancer rates are rising in younger age groups, it’s thought that the increase in certain risk factors — such as carrying extra weight, low levels of physical activity, and an unhealthy diet — may play a role.

It’s important to see your doctor if you develop any warning signs of colorectal cancer, regardless of how old you are. They can order screening tests that can help detect colorectal cancer at an early stage.