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

The idea of having any cancer, let alone colon cancer, is terrifying. Colorectal cancer is the third-most common cancer worldwide and is ranked second for the most cancer-related deaths.

While colon cancer is not something anyone wants to think about, it should be on your radar when you use the toilet. The signs of colon cancer are detectable early on, and the sooner it’s caught, the better your colon cancer survival rate.

We asked the experts directly about colon cancer symptoms, especially the one that’s often missed—but know that for some people, colon cancer can be present even with no symptoms at all, so keep up your routine screenings, even if you feel fine!

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The Top Colon Cancer Symptom 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.

What causes rectal bleeding? Well, it’s complicated because there are several causes of rectal bleeding, some less serious than colon cancer. “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,” Schoen explains.

Hemorrhoids can also cause pain with rectal bleeding, though the rectal bleeding is usually bright red. However, rectal bleeding caused by colon cancer can also be bright red, though tumors that are slowly bleeding may show dark red or black stools. “Because it’s not always hemorrhoids. It could be something bad, like cancer, and it needs to be addressed and evaluated,” Schoen adds.

Rectal bleeding is not something people should brush off without consulting a doctor as it is one of the earliest signs of colon cancer, adds Dr. Arielle Kanters, MD, a colorectal surgeon at Cleveland Clinic: “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.”

Related: FDA Approves Colonoscopy Prep Drink That Actually Tastes Like a Sports Drink

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 Schoen.

What kind of change in bowel habits indicates cancer? This would not be going on vacation and getting constipated because you’re not used to eating foreign cuisine. A change in bowel habits could also happen because of age or insufficient fiber in the diet. Schoen says the key is to watch for sudden changes in bowel habits without obvious cause.

Kanters says unexplained weight loss could be a potential sign of early colon cancer. According to the American Cancer Society, losing over 5% of body weight in a year without trying is a medical concern. Another issue is unexplained anemia, which Kanters says can manifest as “low blood counts, feeling tired and energy loss.”

Related: This Is the #1 Most Important Screening To Get Every Year if You’re 50 or Older

Why Routine Cancer Screenings Are So Important

Ideally, doctors would prefer catching and treating colon issues early enough before they develop into cancer. Routine colon cancer screenings such as a stool test, flexible sigmoidoscopy and a colonoscopy are all options to check for polyps or cancer.

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 note. “We always say that the best cancer is a cancer you don’t get,” Schoen emphasized.

Related: The Early Pancreatic Cancer Signs Most People Miss, According to a Gastroenterologist

Thanks to more people getting screened for colon cancer, the number of cancer cases has dropped since the mid-1980s in older adults. However, doctors are seeing an upward trend in colorectal cases in people younger than 50.

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

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