Colon and rectal cancer

Who is this page for?

If you or someone in your family has just heard they have bowel cancer, the news is heavy. Here we want to explain, without frightening you and without empty comfort, what the disease is and what the usual path looks like. This page does not replace your treatment team’s opinion; every patient has their own situation.

What are colon and rectal cancer?

The colon and rectum are parts of the large bowel, and the rectum is the last part, before the anus. The cancer starts in the cells of the inner lining of the bowel. According to ASCRS, almost all of these cancers start from a polyp, and a polyp usually takes years to become cancer, which is why colonoscopy and removing polyps can prevent the disease. Colon and rectal cancer start from the same type of cell, but because of their location and the way they spread, their treatment differs.

Symptoms

Many bowel cancers cause no symptoms at first and are found at screening. Symptoms that may occur:

• A change in bowel habit, such as new and persistent diarrhea or constipation, or thinner stools
• Blood in the stool, bright red or very dark
• Persistent abdominal pain or bloating
• Unexplained weight loss
• Tiredness (sometimes from anemia)

These symptoms have other causes too and having them does not mean cancer, but they need to be checked. ASCRS says the symptoms of rectal cancer are often mistaken for hemorrhoids. That is why not every bleed should be assumed to be a hemorrhoid. See the article “Is every blood in the stool a hemorrhoid?”.

Diagnosis and staging

• Colonoscopy is the most common way to diagnose it. A sample (biopsy) is taken from the suspicious spot and a pathologist examines it. ASCRS says there is currently no reliable blood test to diagnose colon cancer.
• Imaging: CT and sometimes MRI or PET to see how far the disease has spread. For the rectum, MRI and endorectal ultrasound show more clearly how deep the tumor goes and the lymph nodes.
• Blood tests: a blood count (anemia) and CEA, a protein some tumors make, used mostly to follow up for recurrence.

A specialist team (surgeon, oncologist, pathologist and radiologist) reviews the results together. The NHS says a specialist nurse is usually the patient’s main contact.

Staging (0 to 4) shows how far the cancer has gone:

• Stage 0: only in the inner lining
• Stage 1: into the layers beneath but not through the bowel wall
• Stage 2: deep into or through the wall but not in the lymph nodes
• Stage 3: reached nearby lymph nodes
• Stage 4: spread to distant places such as the liver or lungs

ASCRS says the final stage is sometimes not complete until after the operation and the examination of the lymph nodes.

Treatment options

Treatment is decided by the stage, the place of the tumor, your general health and your own wishes.

Colon cancer

• Surgery is the main treatment. The diseased section of bowel is removed together with nearby lymph nodes, and the two healthy ends are usually joined (anastomosis). The operation can be open or minimally invasive (laparoscopic or robotic).
• In stage 0, removing the polyp at colonoscopy or a local removal is sometimes enough.
• Chemotherapy is usually for stage 3 and 4, and for some high-risk stage 2 patients. Drugs such as 5-fluorouracil and oxaliplatin are named. It starts a few weeks after the operation and is usually given as an outpatient.
• Radiotherapy is rarely used for the colon.

Rectal cancer

• If the tumor is limited to the bowel wall and no nodes look suspicious, surgery alone is sometimes enough. For a very early tumor, local removal through the anus may be enough.
• If the tumor has gone deeper or nodes look suspicious, chemotherapy and radiotherapy are usually given first and then the operation. The combinations vary. NCI says treatment before the operation may also help control of stool afterwards.
• A bag (colostomy or ileostomy) may be needed, temporary or permanent. Permanent is less common.
• ASCRS says rectal surgeons often use a minimally invasive approach.
• Sometimes the final pathology shows more advanced disease than expected, and more treatment may be needed.

Other treatments

For advanced or recurrent disease, targeted therapy, immunotherapy, and liver or lung surgery are also described in the sources. These need to be discussed with an oncologist. NCI says taking part in a clinical trial can be an option at any stage.

After the operation and during treatment

• For the first few days you usually have pain, controlled with medicine. You are asked to get up and walk very soon. Tiredness, constipation or diarrhea are common.
• ASCRS says light walking after discharge is advised and heavy lifting may be limited to reduce the risk of a hernia.
• Common complications of the operation: wound infection, abscess, urinary infection, pneumonia. A leak at the join in the bowel is less common. ASCRS says about one in five patients has some kind of complication, from mild to one needing another operation. Smoking, steroids and diabetes make healing worse.
• Side effects of chemotherapy: tiredness, nausea, diarrhea, mouth sores, tingling in the hands and feet. Most improve after treatment ends.

Follow-up after treatment

ASCRS (based on ASCO guidance) writes in general terms:

• Visits every 3 to 6 months for the first few years, then every 6 months until year five
• CEA blood test every 3 months in the early years, and an annual CT if advised
• Colonoscopy about a year after the operation, then according to the findings (later intervals at least several years)
• For rectal cancer, sometimes periodic examination of the rectum

This schedule is not the same for everyone and the treatment team will set it for you. Report any new symptom (bleeding, change in bowel habit, weight loss).

Family

First-degree relatives of a patient (parents, siblings, children) usually need to be screened earlier and more carefully. In the article “When should I start screening colonoscopy?” we explain that recommendations differ between guidelines.

When to call

Call the treatment team if, during or after treatment:

• You have fever, chills, or redness and discharge from the wound
• You have new or worse abdominal pain
• You have persistent vomiting or cannot drink fluids
• You are not passing gas or stool and the abdomen is swollen
• You have bleeding from the anus
• A calf becomes painful and swollen

Chest pain, sudden shortness of breath or heavy bleeding is an emergency: call 115 (Iran’s emergency number). Every patient’s treatment plan is different; ask your doctor about your own situation.