With more and more young people being diagnosed with colorectal cancer, it’s natural to be nervous about the disease.

Rates of colorectal cancer in people under 50 have been increasing since the 1990s, according to Dr. Michael Cecchini, a co-director of the colorectal program at the Center for Gastrointestinal Cancers and medical oncologist at Yale Cancer Center.

The exact reason why rates are increasing is unknown. Experts “think it’s something lifestyle and environmental, but exactly what that is, we don’t know,” Cecchini said. Researchers are investigating what could be happening. In the meantime, it’s important that you stay alert about colorectal cancer ― even if you’re young.

Part of this is knowing the warning signs. And there’s one surprising symptom in particular that’s been gaining attention on social media: pencil-thin poop.

As one TikTok user explained on the platform, she noticed that her stools were thinner than normal, along with other red-flag symptoms like unexplained weight loss and diarrhea. She thought that she had irritable bowel syndrome, so she didn’t go to the doctor at first. When she finally did, she was diagnosed with stage 4 colon cancer.

Here’s what experts say about this particular issue:

Narrow stool can be a red flag.

Doctors will sometimes see patients whose “stools are much thinner, or they’re pencil in thickness and size, which is a description that some patients with colorectal cancer will have,” Cecchini said.

This tends to occur if tumors are present near the end of the colon or if they line the entire inside of the colon, which narrows whatever stool passes through, Cecchini explained.

Healthy stool should be long and sausage-shaped, according to Medical News Today, and come out as one piece or several smaller pieces. What’s most concerning is when thin stools are a new change that’s persistent, said Dr. Jeffrey Dueker, a gastroenterologist at UPMC and an associate professor of gastroenterology at the University of Pittsburgh School of Medicine.

According to Dueker, any noticeable alteration in your bowel habits could be a potential red flag (but, he stressed, is not always a sign of colon cancer). In addition to a change in stool shape or consistency, this can include going to the bathroom more or less often.

Pencil-thin poop is one of the less common signs of colorectal cancer. “When it exists, it is highly concerning,” Cecchini said. “It’s just not one of the more common symptoms of the disease.” The more widespread signs are blood in the stool and abdominal pain. Unintentional weight loss is another sign. And some cases of colorectal cancer have no symptoms at all.

If you notice any symptoms, you should tell your doctor.

You should never discount your symptoms, Cecchini said, if you notice blood in your stool, chronic abdominal pain, a change in bowel movements, or unexplained weight loss, it’s important that you tell your doctor.

“It’s very easy in younger individuals to think, ‘Oh, it’s just hemorrhoids,’ or something like that ... and it may be, but also those things can coexist,” said Cecchini. “People certainly have hemorrhoids and cancer, or it can be something else completely.”

In general, getting a colonoscopy or another colorectal cancer screening is the best way to lower your risk or catch it in the early stages. You can undergo “screening with colonoscopy or stool-based tests,” Cecchini said. Chat with your doctor to determine the best screening for you.

For most people, screenings start at 45. But if you have any of the symptoms mentioned above or meet certain criteria, you may be eligible for a colonoscopy before 45, Dueker said.

“Anyone with a first-degree relative — mother, father, brother, sister, son or daughter — that has had colon cancer, especially if that person was diagnosed before the age of 50, is going to be at higher risk for colorectal cancer because of that family history, and should speak to their doctor about when they should start getting colonoscopies,” Dueker explained.

If you’ve had inflammatory bowel disease or radiation treatment to the pelvic or abdominal area, or if you have certain genetic syndromes or a personal history of colon cancer, you would also want to get a colonoscopy before 45, Dueker noted.

Suffice to say, it’s important to keep your doctor informed of your medical history and any potential issues you might be experiencing. But while you should take all of this seriously, you also shouldn’t panic.

“All of these symptoms don’t necessarily mean ... you have colon cancer,” said Dueker. Instead, they could mean that a colonoscopy is necessary to determine what is going on. And while the cause could be colon cancer or a precancerous polyp, detecting the disease early is the best way to manage it.

“It’s important to catch cancer early through screening or alerting to some of ... these symptoms so that we diagnose cancer at an earlier stage, where it’s more treatable and hopefully curable,” Cecchini said. “We still cure the majority of people with this cancer every year.”This article originally appeared on HuffPost.