saudigastro.com/patients/colorectal-cancer
Category
Serious
Red flags
4
This article is educational and does not replace your doctor's advice. Seek urgent care for any red-flag symptoms.
What is it?
Colorectal cancer is a cancer of the colon (large intestine) or the rectum (the last part of the bowel before the anus). It almost always begins as a polyp, a small growth on the inside lining that is not cancer at first. Over years, some polyps can change into cancer. If it is found while still confined to the bowel wall, surgery can often cure it. If it spreads to nearby lymph nodes (small immune glands) or to other organs such as the liver or lungs, treatment is more complex but often still effective.
How common is it?
Colorectal cancer is one of the most common cancers in Saudi Arabia and worldwide, and it is being diagnosed more often in adults under 50 than in the past. The reasons for the rise in younger adults are not fully understood. Because it grows slowly and screening works well, it is also one of the most preventable cancers.
Why does it happen?
It develops when cells in the bowel lining gain changes (mutations) that make them grow out of control. Risk goes up with age, a family history of colorectal cancer or polyps, long-standing inflammatory bowel disease (ulcerative colitis or Crohn's colitis), a diet high in red and processed meat and low in fibre, obesity, little physical activity, smoking, heavy alcohol use and type 2 diabetes. A small share are caused by inherited conditions such as Lynch syndrome (inherited high risk of bowel and other cancers) and familial adenomatous polyposis (FAP), which causes hundreds of polyps from a young age. A family history, especially of cancer in a close relative under 50, should be shared with your doctor.
Symptoms
- Blood in the stool or bleeding from the back passage
- A lasting change in bowel habit: new constipation, diarrhoea, or thinner stools
- Feeling that the bowel does not empty fully, or needing to go repeatedly
- Iron-deficiency anaemia (low blood count) causing tiredness, paleness or breathlessness
- Unexplained weight loss and loss of appetite
- Persistent belly pain, cramps or bloating
- A lump in the belly or around the back passage
- Often no symptoms at all in the early stage, which is why screening matters
Red flags — seek urgent medical care
Blood in the stool, or black or tarry stools
Must always be checked. Do not assume it is piles (haemorrhoids), especially over age 40 or with other symptoms.
Bowel habit change lasting more than a few weeks
Needs assessment, usually with a colonoscopy.
Unexplained weight loss or anaemia
May be caused by slow, hidden bleeding from a tumour.
Severe belly pain with vomiting, a swollen belly and not passing wind or stool
Possible bowel blockage. Emergency.
How is it diagnosed?
The key test is colonoscopy: a flexible camera passed through the back passage to look at the whole colon, take biopsies (small samples) and remove polyps. A biopsy under the microscope confirms cancer. Blood tests include a blood count and CEA, a marker that helps follow treatment. CT scans of the chest, abdomen and pelvis check whether the cancer has spread; MRI of the pelvis is used for rectal cancer to plan treatment. Tumours are often tested for genetic features (such as mismatch repair status, RAS and BRAF) that guide treatment and can point to Lynch syndrome. Doctors describe how far the cancer has grown in stages: stage I and II are limited to the bowel wall, stage III has reached nearby lymph nodes, and stage IV has spread to distant organs. Your case is discussed by a multidisciplinary team (MDT), a meeting of surgeons, cancer doctors, radiologists, pathologists and nurses.
What the latest science says
Treatment is increasingly tailored to the tumour's genetic features. Immunotherapy can work very well for tumours with a mismatch-repair deficiency (also called MSI-high), and targeted medicines are used for tumours with certain mutations. For some rectal cancers, giving chemotherapy and radiotherapy before surgery is now standard, and in selected people a watch-and-wait approach may be considered by expert teams.
Outlook — what to expect
Outcome depends mostly on the stage at diagnosis. Cancers found early, confined to the bowel wall, are often cured. Cancer that has reached lymph nodes can still be cured in many people with surgery plus chemotherapy. Cancer that has spread to other organs is less often curable, but can sometimes be controlled for long periods, and in selected people with limited spread to the liver or lungs, surgery may still offer cure. Your team will give you an individual outlook; statistics describe groups, not individuals.
Treatment
Habits & Lifestyle
Healthy habits lower the risk of colorectal cancer and support recovery during and after treatment.
- Join screening when it is due. Screening is recommended from the age set in the Saudi national and SGA guidance (for average-risk adults it commonly starts at 45 to 50), and earlier with a strong family history. Ask your doctor what applies to you.
- Do not ignore bleeding or a change in bowel habit; see a doctor even if you were screened recently.
- Stay active (regular walking or exercise), keep a healthy weight, do not smoke, and limit alcohol. Activity also helps during and after treatment.
- Tell your relatives if you are diagnosed. Close relatives may need earlier or more frequent screening, and genetic counselling is offered if Lynch syndrome or FAP is suspected.
Diet
No food can cure or cause cancer on its own, but overall diet matters for prevention and for staying strong during treatment.
- Prevention: eat plenty of vegetables, fruit, legumes and whole grains; limit red meat and avoid processed meats such as sausages and deli meats.
- During treatment: aim for enough calories and protein to maintain weight. Small frequent meals and a dietitian's help are valuable if appetite is poor.
- After bowel surgery your diet may need to be adjusted for a while. Follow the advice from your surgical team.
- Be careful with supplements and "cancer-curing" products; some interfere with chemotherapy or harm the liver. Ask your cancer team first.
Medications
Medical treatment is chosen by the MDT based on the stage and tumour features. Treatments and side effects differ from person to person.
- Chemotherapy: given after surgery to lower the chance of the cancer returning (adjuvant), or before surgery or for spread disease. Common side effects include tiredness, nausea, low blood counts and nerve tingling. Your team can treat many of them.
- Targeted therapy: medicines aimed at specific features of the tumour, usually for advanced disease.
- Immunotherapy: helps the immune system attack cancer. It is particularly useful for tumours with mismatch-repair deficiency (MSI-high). Report new diarrhoea, rash, breathlessness or yellow skin to your team promptly.
- Radiotherapy plus chemotherapy: often used for rectal cancer, usually before surgery, to shrink the tumour and reduce the chance of it returning in the pelvis.
- Supportive medicines for nausea, pain, anaemia and low mood are an important part of care. Never hesitate to ask for them.
Procedures & Surgery
Surgery is the main curative treatment for most colorectal cancers that have not spread widely.
- Polypectomy or local removal at colonoscopy can be enough for very early cancers inside a polyp.
- Surgery (colectomy or rectal resection) removes the part of the bowel with the tumour and nearby lymph nodes. It is often done by keyhole (laparoscopic) or robotic techniques, which can speed recovery.
- A stoma (an opening on the belly where bowel contents collect in a bag) is needed sometimes, either temporarily to let the join heal or occasionally permanently, mostly with low rectal cancers. Stoma nurses teach you how to manage it, and most people return to normal activities. See the article "Living with a Stoma" (stoma-care).
- Surgery or ablation for limited spread to the liver or lungs in carefully selected people.
- Follow-up after treatment: regular visits, blood tests (CEA), scans and colonoscopy, for several years.
Living with the condition
- A cancer diagnosis is overwhelming. Fear, sadness, anger and poor sleep are normal. Ask your team about psycho-oncology, counselling, support groups and social-work support.
- Bring a family member to appointments, write down questions, and ask for plain explanations of the plan.
- Bowel function may change after surgery (urgency, frequent stools). This often improves over time, and there are treatments and exercises that can help.
- Talk about sexual health, fertility and work early; these are part of cancer care too.
- Palliative care teams help control symptoms at any stage and are not only for the end of life.
In the Saudi context
Colorectal cancer care is available at Saudi tertiary and oncology centres with multidisciplinary tumour boards, minimally invasive surgery, chemotherapy, radiotherapy and genetic counselling. National Saudi colorectal cancer screening guidance (2026) is available on the SGA platform; many centres offer screening through colonoscopy or stool tests. Family members of patients should ask their doctor about earlier screening.
Questions to ask your doctor
Save this list or print it before your appointment — doctors appreciate prepared patients.
- What stage is my cancer, and what is the goal of treatment (cure or control)?
- Has my tumour been tested for mismatch repair, RAS and BRAF, and does that change my options?
- Will I need a stoma, and if so, is it temporary?
- Should my relatives be screened earlier, and should I see a genetic counsellor?
- What support is available for my emotional wellbeing and for my family?
- What follow-up will I need after treatment?
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Status: Approved for publication by SGA; individual clinician review is ongoing · Published 24/04/2026
For general education only; it does not replace your doctor’s advice. Individual clinician review of this guide is ongoing. SGA clinician? Review this guide