A 41-year-old woman thought she had food poisoning and haemorrhoids. A colonoscopy revealed a 6cm tumour in her rectum, and she was later diagnosed with stage 3 colorectal cancer.

Kara Miller, a South London resident, said her symptoms were initially misdiagnosed. But when they persisted, a faecal immunochemical test (FIT) came back positive, prompting additional testing that revealed the tumour.

Miller said doctors told her the cancer had spread to her lymph nodes. Miller underwent chemotherapy, radiotherapy and surgery and has now cancer-free for three years.

Miller's experience demonstrates how colorectal cancer can sometimes cause symptoms that are mistaken for more common digestive issues. Bowel cancer is more common in older adults, but it can also affect younger people.

What Are the Warning Signs of Colorectal Cancer?

Colorectal cancer can cause bowel changes, bleeding and other digestive issues. However, these symptoms can have a variety of other causes, making them easy to miss.

Possible warning signs include blood in the stool or bleeding from the rectum, persistent changes in bowel habits such as diarrhoea, constipation or more frequent bowel movements, and the sensation that the bowel has not emptied completely after a bowel movement.

People with colorectal cancer may also experience abdominal or rectal pain, unexplained weight loss, fatigue and shortness of breath. These latter symptoms can sometimes be related to anaemia caused by blood loss. In some cases, colorectal cancer can cause bowel obstruction, resulting in abdominal cramps, bloating, vomiting, constipation or difficulty passing wind.

Having one or more of these symptoms does not necessarily mean that someone has cancer. Blood in the stool, for example, is frequently caused by haemorrhoids, while changes in bowel habits can have a variety of other causes. However, any unusual or persistent symptoms should be evaluated by a healthcare professional.

Doctors may use a faecal immunochemical test (FIT) to look for tiny amounts of blood in stool and may recommend additional testing, such as a colonoscopy, based on the results and symptoms.

Can Colorectal Cancer Affect Younger Adults?

Although colorectal cancer is more common in older adults, it can also affect younger people. In fact, rates of colorectal cancer among young adults have been increasing in recent years.

According to the American Cancer Society's 2026 statistics, colorectal cancer rates in the United States increased by about 3% per year between 2013 and 2022 among adults aged 20 to 49, while rates fell among those aged 65 and older. The increase has been particularly noticeable in cancers of the sigmoid colon and rectum.

Early-onset colorectal cancer, which is defined as cancer diagnosed before the age of 50, is also increasing in several countries. Cancer Research UK describes the rise as a global phenomenon, with younger-onset bowel cancer rates increasing in 27 of the 50 countries and territories studied.

The reasons for this trend are not entirely clear. Certain risk factors, such as a family history of colorectal cancer, inherited genetic conditions, inflammatory bowel disease and some lifestyle factors, can raise a person's risk. However, younger people with no known risk factors can also develop colorectal cancer.

Colorectal cancer is less common in younger adults, so persistent symptoms may be attributed to other conditions. This is not to say that every digestive symptom is a sign of cancer, but unusual or ongoing changes should not be overlooked simply because someone is young. If symptoms persist, worsen or keep coming back, people should speak with a healthcare professional rather than assume they are harmless. Getting persistent symptoms checked can help identify the cause and determine whether further testing is needed.

When Should You Get Bowel Symptoms Checked?

Persistent changes in bowel habits, rectal bleeding or other unexplained digestive symptoms should not be ignored, especially if they continue or worsen. While these symptoms are frequently caused by conditions other than cancer, a healthcare professional can help determine whether further evaluation is required.

A doctor may ask about the symptoms, medical and family history, and how long they have been present. Depending on the circumstances, they may suggest tests such as a FIT or other investigations to determine the cause.

People should also seek immediate medical attention if they experience severe abdominal pain, persistent vomiting, significant abdominal swelling or an inability to pass stool or wind, as these can be symptoms of a bowel obstruction.

Miller's experience demonstrates that age alone does not rule out colorectal cancer. Persistent symptoms do not always indicate cancer, but having them checked can help identify the cause and ensure proper treatment if necessary.

Although colorectal cancer is less common in young people, its incidence has been increasing. Persistent changes in bowel habits, rectal bleeding or unexplained digestive symptoms should not be assumed to be cancer, but they should also not be ignored.

Recognising unusual or persistent symptoms and seeking medical advice can help identify the underlying cause and ensure that appropriate testing and treatment are provided when necessary.

Frequently Asked Questions

  • What are the warning signs of colorectal cancer?
    Warning signs include blood in the stool, persistent changes in bowel habits, abdominal pain, unexplained weight loss, and fatigue.
  • Can younger adults get colorectal cancer?
    Yes, although it is more common in older adults, colorectal cancer can affect younger people, and rates have been increasing among young adults.
  • When should you get bowel symptoms checked?
    Persistent changes in bowel habits, rectal bleeding, or other unexplained digestive symptoms should be evaluated by a healthcare professional, especially if they continue or worsen.