The Early Colon Cancer Sign Most People Miss, According to Gastroenterologists

Colon cancer is among the most common types of cancer in America, with approximately 106,000 new cases reported in the United States each year, according to the American Cancer Society. The good news: it’s often easily treatable when caught in the early stages—which is why it is so important to be alert for any potential symptoms of colon cancer. And which signs do people often miss?

But what are those symptoms?

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The Top Colon Cancer Sign People Often Dismiss

Rectal bleeding is among the most common early signs of colon cancer. “Bleeding is the number one cardinal symptom,” says Dr. Robert E. Schoen, MD, gastroenterologist at UPMC.

While rectal bleeding may be hard to miss, people often assume it is caused by something less serious. “People have some rectal bleeding, and they think, ‘Oh, it's hemorrhoids. There's nothing to worry about.’ And that can be a fatal mistake,” says Dr. Schoen. “Because it's not always hemorrhoids. It could be something bad, like cancer, and it needs to be addressed and evaluated.”

Dr. Arielle Kanters, MD, a colorectal surgeon at Cleveland Clinic, agrees that this isn’t something people should just brush off without consulting a doctor. “Rectal bleeding without a clear source and without a recent colonoscopy—at least in my mind, as a colorectal surgeon—is [possible] cancer until proven otherwise,” Dr. Kanters says.

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Other Commonly Missed Signs of Early Colon Cancer

The other common early colon cancer symptom many people overlook—or ignore—is a change in bowel habits. “That could be either going from where you were regular and now you've got increasing constipation, or the flip side, a change to diarrhea symptoms,” says Dr. Schoen.

Since bowel patterns can fluctuate for a wide range of reasons, Dr. Schoen says the key is to watch for ongoing issues with no obvious cause. “If you go on vacation, and you get constipated, that doesn't mean you need to rush to your doctor. You want to see some persistency to the symptoms.”

Dr. Kanters says there are other symptoms that could be a potential sign of early colon cancer. “Other common symptoms would be unexplained weight loss and unexplained anemia—so, low blood counts, feeling really tired and energy loss. And changes in the color of your stool. Not just turning bright red, but turning dark black could also be a sign of blood loss, even though it's not the normal color we think of.”

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Why Routine Screenings Are So Important

Doctors stress that ideally, you want to catch colon-related issues before they even cause noticeable symptoms, and way before they ever reach the point of becoming cancer. The American Cancer Society reports that diagnosis rates for colon cancer have been decreasing for the past few decades, due in part to the increase in screenings.

“You need to go get yourself screened,” says Dr. Schoen. “That's the best way to protect yourself from getting and, God forbid, dying of colorectal cancer.”

He notes that colon cancer screenings can not only detect and diagnose cancer, but can frequently prevent cancer from developing in the first place. Growths called polyps, some of which may be pre-cancerous, can often be removed during a colonoscopy. This preventive approach is the best possible outcome, doctors say. “We always say that the best cancer is a cancer you don't get,” says Dr. Schoen.

Next up, find out how Brooks Bell helped convince Ryan Reynolds to get a colonoscopy—and why she wants you to be next