Colorectal Cancer
Colorectal cancer is one of the few cancers we can often prevent outright — and one of the most curable when caught early. A single colonoscopy in middle age can change the course of a life.
What colorectal cancer is — in plain words
Colorectal cancer begins as a small growth called a polyp on the inner lining of the colon or rectum. Most polyps are harmless. A small fraction, over several years, develop the genetic changes that turn them into cancer. Remove the polyp, and you prevent the cancer it would have become — which is why screening colonoscopy works so well.
"Colon cancer" and "rectal cancer" are closely related but managed slightly differently. Rectal cancer (in the last 15 cm of the bowel) often needs radiation as part of treatment; colon cancer usually does not.
Signs and symptoms to take seriously
Blood in the stool
Bright red or dark, mixed with stool or on the paper. Never assume it is "just piles" — get it checked.
Change in bowel habit
Persistent loose motions, persistent constipation, or a new sense of incomplete emptying that lasts more than a few weeks.
Abdominal pain or bloating
Cramping that comes and goes, or a vague ache that doesn't settle. New, persistent bloating in someone over 45 deserves a look.
Iron-deficiency anaemia
Unexplained tiredness with a low haemoglobin — in any adult over 45, or anyone with risk factors, this should prompt a colonoscopy.
"I've never met a patient who regretted having a colonoscopy. I've met many who wished they'd had one a year earlier."
How colorectal cancer is diagnosed
- Colonoscopy — the gold-standard test. A flexible camera examines the entire colon and rectum; any suspicious area is biopsied on the spot.
- CT scan of chest, abdomen and pelvis — to look for spread to the liver, lungs or lymph nodes.
- MRI of the pelvis — for rectal cancers, MRI is essential to plan surgery and decide whether radiation is needed first.
- CEA blood test — a tumour marker. Not used for diagnosis, but helpful for monitoring after treatment.
- Molecular testing — KRAS, NRAS, BRAF mutations and microsatellite instability (MSI) status guide treatment choices in advanced disease.
Stages — what the numbers mean
Stage I
Cancer confined to the inner layers of the bowel wall. Surgery alone usually cures. Five-year survival above 90%.
Stage II
Cancer through the bowel wall but no lymph nodes involved. Surgery cures most; chemotherapy added for higher-risk features.
Stage III
Lymph nodes involved. Surgery followed by six months of chemotherapy is the standard, and substantially improves cure rates.
Stage IV (metastatic)
Spread to liver, lungs or peritoneum. Not always curable — but a meaningful minority of patients with liver-only spread can be cured with combined chemotherapy and surgery.
How we treat colorectal cancer
Surgery
Removing the affected segment of bowel and the nearby lymph nodes is the foundation of cure. Many operations are done laparoscopically with quicker recovery. For low rectal cancers, a temporary or permanent stoma is sometimes needed — modern stoma care makes this far more livable than patients fear.
Chemotherapy
FOLFOX or CAPOX (oxaliplatin-based combinations) are the workhorses, given after surgery for stage III disease and for some stage II cases. For metastatic disease, FOLFIRI and other regimens enter the picture. Treatment is often six months. Read more about chemotherapy →
Targeted therapy
For metastatic disease, the molecular profile guides the next step:
- KRAS/NRAS wild-type cancers may benefit from EGFR-targeting antibodies (cetuximab, panitumumab).
- BRAF V600E mutated cancers respond to a specific combination (encorafenib + cetuximab).
- HER2-amplified cancers have new targeted options.
- VEGF-targeting drugs (bevacizumab) added to chemotherapy improve outcomes.
Immunotherapy
About 5% of metastatic colorectal cancers are MSI-high (also called dMMR). For these, checkpoint immunotherapy is dramatically effective — often more so than chemotherapy. Every patient deserves MSI testing. Read more about immunotherapy →
Radiation therapy
For rectal cancers, a short or long course of radiation (often with chemotherapy) given before surgery shrinks the tumour and reduces local recurrence. Increasingly, patients with an excellent response are being offered a "watch-and-wait" approach without surgery.
What the outlook honestly looks like
Stage I colorectal cancer has a five-year survival above 90%. Stage III, treated properly, has around 70%. Even stage IV is no longer a uniform outcome — patients with liver-only spread who can have both chemotherapy and liver surgery have 30–50% long-term survival, and immunotherapy has been transformative for MSI-high cases.
Screening — the real prevention
- Colonoscopy every 10 years from age 45 for people at average risk. If polyps are found, the interval shortens.
- Earlier and more frequent screening for those with a family history of colorectal cancer, known Lynch syndrome or familial polyposis, or longstanding inflammatory bowel disease.
- Stool tests (FIT, faecal immunochemical test) annually are a reasonable alternative for those who cannot or will not have colonoscopy — though a positive result still requires a colonoscopy.
Life during treatment
Many patients on adjuvant chemotherapy continue working part-time. Oxaliplatin can cause a tingling in the fingers and toes, especially in the cold — wearing gloves and avoiding cold drinks during winter helps. Diarrhoea and mouth soreness are common and manageable. For patients with a stoma, our nursing team will spend whatever time it takes to make you comfortable with the daily routine.
After treatment — survivorship
Follow-up after curative treatment includes regular clinic visits, CEA blood tests, surveillance CT scans, and a follow-up colonoscopy at one year. Most recurrences happen within the first three years, so this period is the most intensive. Read about survivorship care →
Concerned about a colonoscopy report or a new diagnosis?
Bring all the reports — the colonoscopy notes, the biopsy result, the scans. We will go through them and lay out the plan.
Medically reviewed by
Dr. Rehan Abdullah
Dr. Rehan Abdullah is a dual-trained clinical and radiation oncologist with over a decade of experience treating both solid tumours and hematologic malignancies. He serves as Consultant Oncologist at INMOL Hospital and sees patients at Farooq Hospital and Healthnox Medical Center, Lahore. Read full profile →
This page is patient education, not a substitute for an in-person consultation. Cancer care must be individualised. Read our medical disclaimer →