The common symptoms of rectal cancer include rectal bleeding, bloody stool, pain in the lower abdomen or pelvic area, and bowel habit changes. In the early stages, rectal cancers may not cause symptoms. However, routine screening can detect them even without symptoms.

Rectal cancer is a medical condition where cells in the rectum mutate and start growing atypically. The disease is also called colorectal cancer — a general term for cancers that develop in the rectum or colon. However, it is important to note that colon cancer and rectal cancer have different treatment options.

According to the Centers for Disease Control and Prevention (CDC), colorectal cancer is the fourth most common cancer and the fourth leading cause of death related to cancer in the United States.

This article will discuss the symptoms of colorectal cancer and its symptoms in the advanced stages of the disease. It will also discuss when rectal bleeding is a cause for concern and when to speak with a doctor.

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The American Cancer Society (ACS) states that colorectal cancer might not cause any symptoms in the early stages.

Additionally, a 2015 review states that doctors diagnose many colorectal cancer cases after the onset of symptoms, which usually indicates locally advanced cancer.

Some common symptoms of colorectal cancer include:

  • rectal bleeding
  • changes in bowel habits that last for more than a few days, such as diarrhea and constipation
  • narrow, ribbon-like stool
  • blood in stool where red blood is visible or changes the color of stool to black or dark brown
  • abdominal pain
  • cramping or feeling of gas in the abdomen
  • nausea and vomiting
  • the sensation that the bowel is not emptying even after a bowel movement
  • fatigue and weakness
  • unintended or unusual weight loss

Is pain a symptom of colorectal cancer, and what does it feel like?

Colorectal cancer can cause persistent cramps, pain, or aches, particularly in the abdominal and pelvic areas. This is more common in the later stages of the disease.

It could feel similar to the pain that occurs due to indigestion and can be severe. A person may also experience pain while emptying their bowels.

Rectal bleeding can develop due to many less serious causes, such as anal fissures or hemorrhoids. However, it is also one of the common symptoms of colorectal cancer.

If a person is experiencing rectal bleeding, they may notice:

  • blood on the toilet paper after wiping
  • red streaks on the outside of the stool
  • the water in the toilet bowl has turned pink
  • blood in the stool, causing it to be dark in color

Studies indicate that only a few people with rectal bleeding seek medical attention.

What color would the blood be, and how much blood is cause for concern?

Colorectal cancer can cause rectal bleeding with bright red blood. In combination with stool, it can make the stool appear dark brown or black.

However, noticing small streaks of blood on the stool or when wiping is not always a cause for alarm, as minor issues, such as constipation, hard stool, and a small tear in the anus, can cause it.

According to the United Kingdom’s National Health Service (NHS), if a person experiences a small amount of one-off bleeding, it is not usually a cause for concern.

However, a person should still contact a doctor to rule out colorectal cancer. People should also consult a doctor as soon as possible if they experience large volume, constant bleeding.

Other causes of rectal bleeding

While rectal bleeding with bright red blood is one of the symptoms of colorectal cancer, there are other things that can cause it. Hemorrhoids are the most common cause of rectal bleeding.

Some other causes include:

  • colorectal or anal polyps
  • hard stools
  • anal fissures
  • inflammatory bowel disease (IBD)

Depending on the cause, a person may also experience pain when emptying their bowels and itching.

As the cancer progresses and spreads throughout the body, it can cause additional symptoms, such as:

  • jaundice, which refers to the yellowing of the skin and mucus membranes
  • bone pain
  • difficulty breathing
  • headaches, seizures, or dizziness

The symptoms can vary depending on where the cancer has spread to.

Learn more about metastatic colorectal cancer.

Colorectal cancer symptoms overlap with those of benign conditions of the rectum. Therefore, it is important for a person to contact a doctor if they experience any of the symptoms relating to colorectal cancer.

It is also important for people to attend regular colorectal cancer screenings. This can help detect the disease in its early stages, improving a person’s outlook.

The ACS recommends that those with an average risk of colorectal cancer begin screenings from the age of 45 years. A person has an average risk of colorectal cancer if they do not have:

  • a personal or family history of colorectal cancer or polyps
  • a history of IBD
  • hereditary colorectal cancer syndrome
  • a personal history of receiving radiation to the abdomen to treat a previous cancer

Common symptoms of colorectal cancer include rectal bleeding, changes in bowel habits, and blood in the stool.

It is best to speak with a doctor if a person notices some symptoms or unusual body changes.

A doctor can conduct tests to determine the cause of the changes. If they suspect colorectal cancer, they will refer a person to an oncologist for further testing and treatment.