Skip to main contentLast updated: 03-Nov-2026
Dr Harsh Shah
MS, MCh (Surgical Gastroenterology), DrNB (Surgical Gastroenterology)
Registered with Gujarat Medical Council, Reg. No. G-38738
Gastro & Cancer Surgeon
Dr. Jivraj Mehta Hospital, Vasna, Ahmedabad · 18 years of experience
In short
Most rectal cancers have no single cause. Daily habits, long-standing bowel disease, age and family genes add up over many years.
Alcohol, smoking, weight and processed meat raise the risk a little. Colitis that has lasted years and some inherited syndromes raise it much more.
If a close relative had bowel cancer, or you are under 50 with symptoms, tell your doctor early. A simple family tree can change your check-up plan.
The full plan of care is on the middle rectal cancer surgery page. This post explains who is at risk, and why, in plain words.
No one factor is a sentence. Risk grows when several factors meet, and most of them are shared with colon cancer.
| Factor | Effect on risk | What you can do |
|---|---|---|
| Alcohol | Raises risk, and the link looks a little stronger for the rectum than for the colon | Cut down, or stop |
| Smoking or tobacco | Raises risk. The link also looks a little stronger for the rectum | Stop. Ask for help to quit |
| Extra body weight | Raises risk | Aim for a steady, healthy weight |
| Type 2 diabetes | Raises risk | Keep sugar under control |
| Processed meat | Raises risk. It is listed as a known cancer-causing food | Eat it rarely |
| Fibre and whole grains | Lower the risk | Eat dal, vegetables, fruit and whole grains daily |
| Regular activity | Lowers the risk, a little less for the rectum than for the colon | Walk or exercise most days |
In India, alcohol and tobacco are common among urban men. This fits the pattern of rectal cancer we see. Changing habits does not remove the risk, but it moves the odds the right way.
Men get rectal cancer more often than women. The disease is also being found at younger ages than before.
People who had pelvic radiation, or this old urine-diversion operation, need regular scope checks. Ask your doctor when to start.
Long-standing ulcerative colitis, and Crohn’s disease that involves the colon, are among the strongest non-inherited risks.
Regular colonoscopy with careful biopsies is the safeguard. Cancer in colitis is often flat and spread over an area, so it is easy to miss on a quick look. If cancer or pre-cancer is found, the usual operation removes the whole colon and rectum and builds an internal pouch.
A small share of rectal cancers run in families. Two conditions matter most: Lynch syndrome and familial adenomatous polyposis.
| Syndrome | What it is | What it means for care |
|---|---|---|
| Lynch syndrome | A fault in genes that repair DNA mistakes. It is the usual inherited cause of rectal cancer | Close scope checks for life. Relatives should be tested. Aspirin may lower risk, but take it only on your doctor’s advice |
| Familial adenomatous polyposis (FAP) | Hundreds of polyps form in the colon and rectum from the teen years | An operation is planned before cancer starts. The choice depends on how many polyps sit in the rectum |
| Attenuated FAP and MUTYH polyposis | Fewer polyps, but still a high risk | Managed much like colon cancer risk |
| Peutz-Jeghers and juvenile polyposis | Rare syndromes with a different type of polyp | Regular scope checks and family advice |
In Lynch syndrome, a standard rectal cancer operation is usually enough, with close checks of the rest of the bowel. Removing the whole colon and rectum is sometimes discussed, but the benefit is not clear and it changes daily life. This is decided one patient at a time.
One test answers two questions. It screens for Lynch syndrome, and it shows whether immunotherapy may work for you.
You can read how the result guides treatment in our post on the rectal cancer pathology report.
Meet a genetic counsellor if your cancer or your family tree fits a pattern. Do not wait for the surgery to be over.
Please share a family tree that goes back three generations. Include cancers of the womb, ovary, stomach, urine tract and skin. Most families do not know this history until someone asks.
There is rarely one cause. Age, alcohol, tobacco, weight, diet, long-standing colitis and inherited gene faults add up over many years. Some people with none of these still develop it.
Only a small share runs in families, mostly through Lynch syndrome or familial polyposis. Having a close relative with bowel cancer still raises your own risk and should change when you start scope checks.
Yes. Both raise the risk, and the link looks a little stronger for the rectum than for the colon. Cutting down or stopping lowers your future risk.
Your risk is higher after about 8 to 10 years of colitis that involves a large part of the bowel. Regular colonoscopy with biopsies is the safeguard, so keep your checks on time.
If your tumour shows lost mismatch repair, or you were under 50, a genetic counsellor can advise which relatives to test. Close relatives may also need an earlier first colonoscopy.
You can lower it by stopping tobacco, cutting down alcohol, keeping a healthy weight, eating more fibre and staying active. Scope checks at the right age find growths before they turn into cancer.
The full range of rectal cancer care starts at the middle rectal cancer page. For questions before you travel, call +91-63555-64601.
Dr Harsh Shah — Dr. Jivraj Mehta Hospital, Vasna, Ahmedabad
Dr. Jivraj Mehta Hospital, Dr Jivraj Mehta Marg, Vasna, Ahmedabad 380007.
Consultations, review of reports and scans, operations and follow-up. OPD Monday to Saturday, 9 am to 5 pm.
Appointments: +91-63555-64601 · +91-63590-11009 · Hospital 079-2663 6363
Directions to the hospital · WhatsApp +91-63555-64601
Worried because someone in your family had bowel cancer, or because you have bleeding or a long-standing gut illness? Risk can be understood, and often lowered. Call, or send a message on WhatsApp, and Dr Harsh Shah will tell you what to check and when. Call +91-63555-64601 Ask on WhatsApp
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