Bowel cancer

Bowel cancer is one of the most commonly diagnosed cancers worldwide. It is most common in people over 50, but it can occur at any age. In its early stages it may cause no symptoms at all, yet when it is found early it can often be treated successfully. Understanding how it develops, what to look for and what treatment involves can help you ask the right questions and take part in your own care.

What is bowel cancer?#

The colon and rectum together are known as the large bowel. Cancer of the large bowel is also called colorectal cancer, and it may be described as colon cancer or rectal cancer depending on where in the bowel it begins.

The bowel is part of the digestive system, which runs from the mouth to the anus. The digestive system breaks down food and turns it into energy, and gets rid of the parts of food the body does not use. The bowel is the long tube that absorbs water and nutrients from food and processes the remaining waste into feces (poo).

How bowel cancer develops#

Bowel cancer starts in the inner lining of the bowel wall. If it is not treated, it can grow into the deeper layers of the wall. From there it can spread to nearby lymph nodes and to nearby organs such as the prostate or bladder. Later it can spread to more distant organs such as the liver or lungs.

Most bowel cancers develop from small growths called polyps. Most polyps are harmless (benign), but some can turn into cancer over time. Because of this, polyps can be removed during a colonoscopy before they have a chance to become cancerous.

Symptoms#

Bowel cancer can develop with no symptoms, which is why screening is important. When symptoms do occur, they may include:

• A change in your usual bowel habits, such as diarrhea, constipation, or smaller and more frequent bowel movements
• Blood in your poo or on the toilet paper
• A feeling of being full or bloated, or a strange sensation in the rectum, often during a bowel movement
• A feeling that the bowel does not empty completely
• A change in the appearance of your poo, such as thin stools
• A blockage in the bowel
• Abdominal (stomach) pain or swelling
• Anal or rectal pain, or a lump in the anus or rectum
• Losing weight for no obvious reason
• Weakness or fatigue, which can be caused by a low red blood cell count (anemia or iron deficiency)

Having these symptoms does not mean that you have bowel cancer, but anyone who notices them should speak to their doctor.

What increases the risk#

The exact causes of bowel cancer are not fully understood, and it can develop without any noticeable symptoms. Some factors are known to increase the risk, including:

• Being aged 50 and over, as the risk increases with age
• Having had bowel cancer, polyps, or some other cancers before
• Having had an inflammatory bowel disease such as Crohn’s disease or ulcerative colitis, particularly for more than 10 years
• Having a large number of polyps in the bowel
• A significant family history of bowel cancer or polyps
• Carrying extra weight or not being physically active
• A diet high in red meat, especially processed meats such as salami, ham, bacon and sausages
• Drinking alcohol or smoking

Bowel cancer in families#

The risk of bowel cancer can be higher if one or more of your close relatives (such as a parent, brother or sister) has had it, especially if they were diagnosed before the age of 55, or if two or more close relatives on the same side of the family have been affected. A family history of some other cancers, such as cancer of the uterus (endometrial cancer), may also increase the risk.

A small number of bowel cancers (about 5–6%) are caused by an inherited faulty gene. Two main genetic conditions occur in some families:

• Familial adenomatous polyposis (FAP) causes hundreds of polyps to form in the bowel. If these polyps are not removed, they may become cancerous.
• Lynch syndrome affects a gene that helps a cell’s DNA repair itself. People with Lynch syndrome have an increased risk of bowel cancer, cancer of the uterus, and other cancers such as kidney, bladder and ovarian cancer.

If you are worried about your family history, talk to your doctor about regular check-ups or ask for a referral to a family cancer clinic.

Types of bowel cancer#

Most bowel cancers are adenocarcinomas, which start in the tissue lining the bowel. Other, rarer types include:

• Squamous cell cancers, which arise in the skin-like cells of the bowel lining
• Neuroendocrine tumors (NETs)
• Small bowel cancer
• Gastrointestinal stromal tumors
• Lymphomas

Diagnosis#

Several tests may be used to diagnose bowel cancer, including:

• A physical and rectal examination
• Blood tests, including a carcinoembryonic antigen (CEA) test and an immunochemical fecal occult blood test (iFOBT)
• Colonoscopy
• CT colonography
• Flexible sigmoidoscopy
• Imaging scans such as CT, MRI or PET-CT scans
• Genetic testing
• Molecular testing, which may be used when advanced bowel cancer is diagnosed to check the biopsy sample for gene mutations or other cell features

Test results may take a few days to come back. It is natural to feel anxious while you wait. It can help to talk to a close friend or relative about how you are feeling, or to speak with a cancer nurse through a cancer support service.

Staging#

Knowing if and how far the cancer has spread is called staging. Staging helps your doctor work out the best treatment for you. A commonly used system is the TNM system, which stands for tumor, node and metastasis and gives numbers to:

• The size of the tumor (T1–4)
• Whether lymph nodes are affected (N1–2)
• Whether the cancer has spread or metastasized outside the bowel (M0–M1)

Based on these numbers, the doctor works out the overall stage:

• Stage 1: the tumor is found only in the inner layers of the bowel wall
• Stage 2: the tumor has spread deeper into the layers of the bowel wall
• Stage 3: the tumor is in any layer of the bowel wall and has spread into nearby lymph nodes
• Stage 4: the tumor has spread beyond the bowel to other parts of the body, such as the liver, lungs, or distant lymph nodes

In many countries about half of all bowel cancers are diagnosed at stage 1 or 2. Ask your doctor to explain the stage of your cancer in a way you can understand, as this helps you choose the best treatment for your situation.

Treatment#

Your health care team will recommend treatment based on what will give you the best outcome, where the cancer is in the bowel, whether and how it has spread, your general health, and your own preferences.

Surgery#

Surgery is the main treatment for bowel cancer. The aim is to remove as much of the cancer as possible along with nearby lymph nodes. It may be performed as keyhole or open surgery.

The most common operation is a colectomy, in which a part of the bowel, the nearby lymph nodes and some surrounding normal bowel are removed. The surgeon takes out the affected section and then joins the two ends together.

Sometimes a stoma (an opening of the bowel onto the abdomen) is made during surgery. Bowel motions then pass through the stoma into a bag. A stoma made from the large bowel is called a colostomy, and one made from the small bowel is called an ileostomy. Some stomas are temporary, to allow the bowel to heal, while others are permanent. Around 1 in 10 people with rectal cancer need a permanent stoma. Before surgery you will be given education and support about living with a stoma.

Chemotherapy and radiation therapy#

Radiation therapy (radiotherapy) is often used before surgery, sometimes together with chemotherapy, to reduce the size and number of cancer cells. It is not used for early colon cancer. Occasionally, if the cancer is more advanced, it may be used after surgery to destroy any remaining cancer cells. Radiation therapy to the pelvis and rectum can affect sexual function and fertility, so it is important to discuss your options before treatment begins.

Chemotherapy may be recommended if the cancer has spread to lymph nodes or other organs. It may be given:

• Before surgery, to shrink the tumor and make it easier to remove
• After surgery, to kill any remaining cancer cells and reduce the chance of the cancer coming back
• On its own, if the cancer has spread to other organs

Treatment for advanced bowel cancer#

Advanced bowel cancer is commonly treated with drugs that reach cancer cells throughout the body. This is called systemic treatment and includes chemotherapy, targeted therapy and immunotherapy.

Chemotherapy drugs affect all rapidly dividing cells, killing cancer cells in the process. Targeted therapy drugs work differently, acting on specific molecules within cells to block cell growth. Immunotherapy uses the body’s own immune system to fight the cancer. Checkpoint inhibitors are the main type of immunotherapy used for the small number of advanced bowel cancers that have a fault in the mismatch repair (MMR) gene. The number of infusions you receive depends on how you respond to the drug (such as pembrolizumab).

The aim of treatment for advanced cancer may be to slow how fast the cancer is growing, shrink the cancer, or manage symptoms. Your doctor will discuss your treatment in detail with you.

Complementary therapies#

Complementary therapies are designed to be used alongside conventional medical treatment such as surgery and radiation therapy. They can increase your sense of control, reduce stress and anxiety, and improve your mood. Always tell your treating team about any complementary medicines you are taking, and never stop your conventional treatment without consulting your doctor first.

Side effects#

All treatments have side effects, which vary depending on the type of treatment. Many are temporary, but some may be permanent. Your doctor will explain the possible side effects before treatment begins. Some side effects can be upsetting and difficult, but help is available if you need it. A cancer support service can connect you with a caring cancer nurse.

Living with bowel cancer#

Living with a stoma#

Having a stoma is a big change, and most people find it takes time to come to terms with it. People often worry about how they will care for it. A stomal nurse will explain how to look after your stoma and tell you about support services.

Sexuality and bowel cancer#

Having bowel cancer and its treatment can change the way you feel about yourself, other people, relationships and sex. These changes can be upsetting and hard to talk about. Doctors and nurses are very understanding and can offer support. You can also ask for a referral to a counselor or therapist who specializes in body image, sex and relationships.

Living with advanced cancer#

Advanced cancer usually means cancer that is unlikely to be cured, but some people live for many months or years with it. Many people think palliative care is only for people who are dying, but it is for any stage of advanced cancer. Doctors, nurses and others who specialize in palliative care can help you live more comfortably by managing symptoms such as pain. Most people continue to have treatment for advanced cancer as part of palliative care, because it helps manage the cancer and improve day-to-day life. Ask your doctor about treatment and palliative care services that may help you.

Caring for someone with bowel cancer#

Caring for someone with cancer can be a difficult and emotional time. If you are caring for someone with bowel cancer, support services for carers can help.

Reducing your risk#

Screening is the most effective way to reduce your risk of bowel cancer. You can also help reduce your risk by:

• Eating a healthy diet with plenty of fresh vegetables and fruit
• Limiting red meat and processed meats
• Maintaining a healthy body weight
• Being physically active each day
• Quitting smoking
• Reducing your alcohol intake

Following this advice does not guarantee you will never get bowel cancer, but it can lower your risk and has other health benefits too.

Screening#

Screening is the process of looking for cancer, or abnormalities that could lead to cancer, in people who do not have any symptoms. It is particularly important for bowel cancer, which often has no symptoms in its early stages.

Many national programs offer regular screening to people within a certain age range, often using a fecal occult blood test (iFOBT). This involves taking tiny samples from two separate bowel motions using a home test kit, which are then sent to a laboratory for testing. Screening ages and intervals vary from country to country, so ask your doctor about the program available where you live.

Most positive tests are not the result of cancer. However, if blood is detected, the doctor is likely to refer you for a colonoscopy. When cancer is found early, there is a much higher chance of treating it successfully.

Key points#

• Bowel cancer is one of the most common cancers and most often affects people over 50, though it can occur at any age.
• In its early stages it may cause no symptoms, but when found early it can often be treated successfully.
• Most bowel cancers develop from polyps, which can be removed during a colonoscopy before they turn cancerous.
• Symptoms can include a change in bowel habits, blood in the poo, abdominal pain, and unexplained weight loss or fatigue.
• Regular screening and a healthy lifestyle are the most effective ways to reduce your risk.

Where to get help#