Colon cancer rates are rising in young people. If you have two symptoms you should get a colonoscopy, a GI oncologist says.

• Cases of colon cancer have risen in younger people by 2% per year since 2011. 
• GI oncologist Dr. James Cleary shared common signs and symptoms to look out for. 
• If you have two of these symptoms at the same time, you should get a colonoscopy, he said. 

Colorectal cancer is on the rise among younger people, but catching it early increases the chances of a full recovery. This means it's crucial to know the symptoms and get tested if they arise, particularly if you have more than one.

Rates of colorectal cancer in people under 50 have been rising by 2% each year since 2011, according to the American Cancer Society. And it's now the deadliest cancer among men that age in the US, and the second deadliest among women.

Around $24.3 billion was spent in the US on colorectal cancer-related healthcare in 2020, accounting for 12.6% of all cancer treatment costs, according to the Centers for Disease Control and Prevention. Comparatively, breast cancer, the cancer with the highest treatment cost, accounts for 14% of all costs, the CDC said.

Most colon and rectal cancers start as small growths, known as polyps, in the lining of the organs. Usually, they are harmless, but sometimes they can develop into cancer.

Often polyps are asymptomatic, so it's important to have regular screenings because those found in the early stages can usually be fully removed, according to Mayo Clinic. The recommended age to start cancer screening is 45, but those with a genetic predisposition, family history of the disease, or other colorectal risk factors may be advised to get tested at a younger age.

"We used to start doing colonoscopies as a screening method at the age of 50, but now the age has been moved back to 45 in recognition that more young people are getting colorectal cancer. So please get your colonoscopy," Dr. James Cleary, a gastrointestinal oncologist at Dana-Farber Cancer Institute in Boston, told Business Insider.

But those who develop signs and symptoms of colorectal cancer before the age of 45 may also want to get screened. "If you're having one symptom, you should think about getting a colonoscopy, but if you're having two of these, statistically speaking, your chances are higher, and you really should go get a colonoscopy," Cleary said.

For example, abdominal pain or cramping and weakness or fatigue are both symptoms of the illness. Although these can be signs of many conditions, if you experience both at the same time you might consider getting tested for cancer.

Cleary shared three of the other common signs and symptoms of colon cancer to look out for.

Iron deficiency anemia

Iron deficiency anemia, which is where a person has low iron levels, can be a sign of colon cancer.

This usually occurs because colon cancer can cause bleeding, particularly rectal bleeding, another symptom of the disease, Cleary said. However, the bleeding can happen on a microscopic level, that a patient wouldn't be aware of.

A loss of blood causes anemia because the red blood cells in the blood contain iron. So if you lose blood, you lose some iron.

"When someone is found to have iron deficiency anemia, I think the important question is always going to be 'why is the person having iron deficiency anemia?' And if you really can't come up with a good cause, that person really should undergo a colonoscopy," he said.

Common symptoms of iron deficiency anemia include tiredness, lack of energy, shortness of breath, and headaches. You can get a blood test to check your iron levels.

Changes in bowel movements

Changes in bowel habits can also be a potential sign of colorectal cancer, but this can show up in a number of ways, Cleary said. If the tumor is low down in the rectum, for example, this can cause a narrowing of the stool because it needs to squeeze past to leave the body.

Changes such as going to the bathroom more often, pencil-thin stools, and blood in the stool are common in colorectal cancer patients, he said.

Other changes can include diarrhea, constipation, and not feeling relieved after a bowel movement.

Unintentional weight loss

Unintentional weight loss can be a sign of any type of cancer, including colon cancer, Cleary said. He tends to see this in patients with very late-stage colon cancer.

"It is usually pretty significant, 10 to 20 pounds over six months to a year," he said, without the patient actively trying.

If people have unintentional weight loss, they should see their doctor and figure out what's going on because it's a high-risk feature, he said, particularly if they are experiencing another symptom, such as rectal bleeding, at the same time.