Rectal Cancer

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Rectal cancer starts in the rectum, the last part of the large bowel. This guide explains the tests, treatment choices and support you may need. You can read one section at a time and return to the parts that matter to you.

Your plan depends on where the cancer is, how far it has grown or spread, its test results and your general health. Your priorities also matter, including bowel control, fertility, sexual health and daily life.

Rectal cancer at a glance

How is rectal cancer different from colon cancer?

The colon and rectum together form the large bowel, so their cancers are often grouped under the word colorectal. The rectum sits within the pelvis, the lower part of the body between the hip bones. It is close to the bladder, reproductive organs and muscles that control the bowel opening. This is why its treatment needs particular attention to bowel, bladder and sexual function.

Surgery is often the first treatment for cancer confined to the colon. Rectal cancer more often needs treatment before surgery. The exact position of the tumour helps decide the plan.

Your first questions

• What do my biopsy and scans show, and are any results still pending?
• What is the aim of treatment, and which treatment comes first?
• How might treatment affect my bowel control and everyday life?
• Who should I contact if symptoms change or I need help?

A biopsy is a small tissue sample checked for cancer. Keep a copy of the biopsy report and your treatment history. Ask for a compact disc (CD) containing your scan images in Digital Imaging and Communications in Medicine (DICOM) format and the software needed to view them, along with the written scan reports. These can help if you seek another opinion.

Understand

Where the rectum sits and what it does

The rectum stores stool before it leaves the body through the anus. Rings of muscle around the anus, called sphincters, help control when you pass stool. Nearby nerves help the bowel, bladder and sexual organs work.

Fatty tissue around the rectum is called the mesorectum. It contains blood vessels and lymph nodes, small structures that are part of the immune system. Its outer covering is called the mesorectal fascia. These tissues matter when planning how to remove the cancer safely.

How rectal cancer can develop

Some rectal cancers develop from a polyp, a growth in the bowel lining. Many polyps never become cancer. Certain types, including adenomas and serrated polyps, can develop abnormal cells over time. Removing these polyps can help prevent cancer.

Dysplasia means abnormal cells that have not yet become an invasive cancer. Invasive means cancer has grown beyond the surface lining into the tissue beneath it. Cancer may grow deeper through the bowel wall, reach nearby lymph nodes or spread to other parts of the body. These findings help determine its stage.

Not every early cancer needs the same operation

A carefully selected small early cancer may be removed through the anus while keeping the rectum. This is called local excision. It leaves the nearby lymph nodes in place. If the removed tissue shows a higher chance of cancer in those nodes, more treatment may be needed.

Symptoms and when to seek help

Possible symptoms include bleeding from the anus, a lasting change in bowel habits, mucus in the stool, or a feeling that you still need to pass stool after going to the toilet. This last symptom is called tenesmus. Unexplained weight loss, tiredness or pain can also occur.

Bleeding may cause anaemia, meaning too few healthy red blood cells to carry oxygen around the body. This can make you tired or breathless. Piles, also called haemorrhoids, and small tears at the anus can cause similar symptoms. They can also occur alongside cancer, so persistent symptoms need checking.

A normal examination with a gloved finger does not rule out rectal cancer. Some tumours are too high to feel. Further tests may still be needed.

Risk, screening and family history

Screening looks for early cancer or polyps before symptoms appear. If you have symptoms, seek assessment even if a previous screening test was normal. Cancer can occur in younger adults as well as older people.

Risk can be higher with previous bowel polyps, a strong family history, or long-standing inflammation of the bowel from ulcerative colitis or Crohn's disease. Smoking, alcohol, excess body weight, little physical activity and some dietary patterns are also linked to risk. A diagnosis does not mean you caused the cancer.

Tests on the tumour and tests for inherited risk

All rectal cancers should have tests for mismatch repair (MMR) and microsatellite instability (MSI). These look for signs that cells cannot properly repair errors in their genetic instructions, called deoxyribonucleic acid (DNA). The results can guide treatment and help identify people who may need tests for inherited cancer risk.

• Deficient mismatch repair (dMMR) means this repair system is not working properly. Microsatellite instability-high (MSI-H) means many changes have built up in short repeated sections of DNA. These results usually identify the same group of cancers and can make immunotherapy an option.
• Proficient mismatch repair (pMMR) means the repair system appears to be working. Microsatellite stable (MSS) means the MSI test does not show this pattern of instability. These cancers usually need a different treatment approach.

A tumour result alone does not prove an inherited condition. An inherited, or germline, test uses blood or saliva to look for a gene change you were born with. A genetic counsellor explains what testing could mean for you and your family.

Inherited conditions include Lynch syndrome and conditions that cause many bowel polyps, such as familial adenomatous polyposis (FAP) and MUTYH-associated polyposis. MUTYH is the name of a DNA-repair gene. Testing may be considered because of your age, family history, multiple cancers or tumour-test results. Having no known family history does not rule out an inherited condition.

If an inherited change is found, close relatives may be offered testing and a screening plan suited to their risk.

Tests and diagnosis

How rectal cancer is diagnosed

Different tests answer different questions. A biopsy confirms the type of cancer. Scans show where it is and help the team plan treatment.

1. 1
   Talk about symptoms and have an examination

   The team asks about bowel habits, bleeding, medicines, family history and how you manage daily activities. A gloved-finger examination may help assess a low rectal tumour.

2. 2
   Camera examination and biopsy

   A thin flexible tube with a camera is passed through the anus to look inside the bowel and take small tissue samples.

3. 3
   Blood tests

   These check for anaemia and assess kidney and liver function. Carcinoembryonic antigen (CEA) is a substance measured in the blood that can help track some bowel cancers.

4. 4
   Pelvic MRI

   This maps the tumour's depth and its relationship to nearby tissues, lymph nodes and the muscles controlling the anus.

5. 5
   CT scan or PET-CT scan

   Computed tomography (CT) uses X-rays to make detailed body pictures. CT of the chest, tummy and pelvis usually checks for distant spread, especially to the liver and lungs. Positron emission tomography combined with CT (PET-CT) may be used for a specific question. It combines pictures of tissue activity with detailed body images.

6. 6
   Team review

   The specialists bring the results together, explain the stage and discuss treatment choices with you.

The camera examination and tissue sample

A sigmoidoscopy examines the rectum and lower colon. A colonoscopy examines the whole colon as well. These camera tests are forms of endoscopy. Checking the rest of the bowel helps find any other polyps or cancers.

The report records the tumour's position, including its distance from the anal verge, the outside edge of the anus. It also describes whether the tumour narrows the bowel. Sometimes a small ink mark, or tattoo, is placed to help locate an area later.

What can a biopsy tell me?

A pathologist, a doctor who examines tissue under a microscope, checks whether cancer is present and what type it is. The biopsy may also describe the grade: how abnormal the cells look and how they may behave. Grade is different from stage, which describes how far the cancer has grown or spread.

A small sample cannot show the full depth of a tumour or all the nearby lymph nodes. Scans and, if surgery takes place, examination of the removed tissue add this information. Sometimes another sample is needed if the first one does not explain a suspicious finding.

What each scan or blood test adds

Understanding the main terms in an MRI report

You do not need to interpret the report alone. These are the findings most likely to affect your treatment plan.

What the tissue report and repair tests mean

Alongside the cancer type and grade, the report includes the MMR or MSI result described above. This can affect the choice of medicines and whether inherited-risk testing is recommended.

If you have surgery after treatment, the report may use ypT and ypN. The letters yp mean that tissue was examined after treatment; T describes the remaining tumour's depth and N describes nearby lymph nodes. Regression describes how much the tumour has responded.

The report also checks the cut edges for cancer and may describe cancer in small blood vessels, lymph channels or around nerves. These are called lymphovascular invasion and perineural invasion. Small cancer deposits outside the main tumour can also affect staging and treatment decisions.

When immunotherapy may avoid surgery

For selected patients with stage 2 or 3 dMMR/MSI-H rectal cancer, immunotherapy can be an initial treatment. A medicine such as dostarlimab helps the immune system recognise and attack the cancer. The specialist team checks the response using examination, camera tests and MRI.

If no cancer is detectable, this is called a complete clinical response. Surgery may then be deferred within a structured follow-up programme. This does not prove cure: regular checks remain essential, and surgery or other treatment may be needed if cancer remains or returns.

This immunotherapy approach does not apply to tumours without dMMR/MSI-H. The team also considers your other health conditions and whether immunotherapy is suitable for you.

Planning your treatment

Understanding your stage

Tumour, nodes and metastasis (TNM) staging for rectal cancer

TNM brings together the tumour’s depth (T), nearby lymph nodes (N) and metastasis (M), meaning spread to distant parts of the body. Think of the bowel wall as layers: an inner lining, supporting tissue, muscle and outer tissue. Stage depends on where cancer has reached, not simply how wide the tumour is.

Lymph nodes are small immune-system structures. Regional nodes are those near or draining the cancer’s starting area; distant spread means cancer has reached a site outside that regional area. Stages describe findings, not a sequence that everyone will pass through.

Stage 0

Abnormal or cancerous cells remain within the inner lining and have not entered the supporting layer beneath it. This is also called in situ disease: the cells remain at their starting site.

Stage 1 (I)

Cancer has entered the supporting layer or muscle of the rectum wall, but has not grown through the muscle. Nearby nodes and distant sites are not involved.

Stage 2 (II)

Cancer has grown through the muscle into outer tissue, the outer covering or a neighbouring organ. No nearby lymph-node or distant spread is found. Some stage 2 cancers have features that increase the chance of cancer returning.

Stage 3 (III)

Cancer has reached nearby lymph nodes, or there are particular cancer deposits in the tissue supporting the bowel. It has not spread to distant sites. The depth of growth and the affected nodes or deposits determine the subgroup.

Stage 4 (IV)

Cancer has reached a distant site, such as the liver, lung or abdominal lining. Direct growth into an organ next to the bowel is different from a separate distant deposit.

MRI helps map the cancer and its distance from the planned surgical cut edge. The exact position, response to treatment and ability to remove it fully all matter within each stage. Selected people with a small amount of distant spread may still be offered treatment aiming to remove or destroy all visible cancer.

Clinical stage is the assessment before surgery, using examination, biopsy and scans. Pathological stage adds the findings from tissue removed during an operation. If you had treatment before surgery, the report may use the prefix yp, as explained under Tests and diagnosis. More detailed results can change the stage; this does not necessarily mean the cancer grew while you were waiting.

Treatment choices for stages 0 and 1

Very early cancers may be removed during a camera procedure or through the anus. Others need surgery to remove part or all of the rectum and nearby lymph nodes. The choice depends on the depth, location and tissue-test results, not just the stage number.

For local excision, the team checks that the tumour is small, accessible and removable in one piece with clear cut edges. The removed tissue can reveal deeper growth or features missed by the first biopsy.

Higher-risk features include very abnormal-looking cells, cancer in small vessels, deep growth into the supporting layer, or tumour budding: single cancer cells or small groups breaking away at the tumour edge. Cancer close to a cut edge, or tissue removed in fragments that cannot be assessed reliably, may also lead to a recommendation for more treatment.

Treatment choices for stages 2 and 3

These cancers have grown through the bowel muscle or reached nearby lymph nodes, without distant spread. Treatment often combines medicines, radiotherapy and surgery. MRI helps show which combination and order are most suitable.

The team pays particular attention to cancer near the planned cut edge, in veins outside the bowel wall, or close to the muscles controlling the anus. Your general health and the MMR/MSI result also affect the choice.

Why treatment may come before surgery

Treatment given before an operation is called neoadjuvant treatment. Total neoadjuvant therapy (TNT) means giving the planned chemotherapy and radiotherapy before surgery. Chemotherapy may come before or after the radiotherapy.

This can shrink the tumour, treat cancer cells too small to see on scans and help deliver the planned treatment before recovery from an operation. For selected dMMR/MSI-H cancers, immunotherapy may be the initial treatment instead.

Some lower-risk or upper rectal cancers may be treated with surgery first, or chemotherapy with radiotherapy added only if needed. Ask why the proposed sequence fits your scan and tissue results.

Cancer that has spread or come back

Stage 4, or metastatic, cancer has spread to a distant part of the body. Recurrence means cancer has returned after treatment. A recurrence may be in the pelvis, elsewhere in the body, or both.

Symptoms may need treatment first

A blocked bowel may need a stoma or, in selected situations, a stent: a tube placed inside a narrowed section to hold it open. Bleeding and pain may need radiotherapy or other treatment. An infection or fistula, an abnormal connection between the bowel and another organ or the skin, may need drainage, antibiotics or surgery.

Your treatment plan at a glance

• Confirm the diagnosis and extent. Bring together the biopsy, repair tests, scans and your health needs.
• Agree the aim and first treatment. This may be local removal, a larger operation, treatment before surgery, immunotherapy for a suitable tumour or medicines to control spread.
• Check the response. The team explains when repeat examinations and scans will take place and what the results may change.
• Agree the next step. Surgery is often needed. Carefully selected people with a complete clinical response may discuss close monitoring while deferring surgery.
• Plan recovery and follow-up. Arrange bowel or stoma support, rehabilitation and the tests needed after treatment.

Treatment options

Removing an early tumour through the anus

Local excision removes a selected early tumour while keeping the rectum. Transanal means through the anus. Techniques include transanal endoscopic microsurgery (TEM, also called TEMS) and transanal minimally invasive surgery (TAMIS). Both use special viewing equipment and surgical instruments through this opening.

This usually means a smaller operation and faster initial recovery than major rectal surgery. It leaves the nearby lymph nodes in place, so careful selection and follow-up are essential. The surgeon aims to remove the tumour in one piece, often with the full thickness of the involved bowel wall, so it can be examined properly.

Risks include bleeding and infection. If the removed tissue shows higher-risk features or cancer at the cut edge, a larger operation or other treatment may be needed. Ask what findings would change the plan and when you will receive the results.

Operations to remove part or all of the rectum

Total mesorectal excision (TME) removes the affected rectum with the surrounding fatty tissue and lymph nodes, keeping their outer covering intact. The aim is to remove the cancer with clear margins. The amount removed depends on the tumour's position and extent.

Surgery may use one larger cut, called open surgery, or several small cuts, called laparoscopic surgery. Robotic surgery is a form of surgery using instruments controlled by the surgeon. The approach should support safe cancer removal; the technique's name alone does not determine the result.

Possible problems include a leak from the bowel join, infection, bleeding or another operation. Longer-term effects may include changes in bowel control, bladder emptying and sexual function. Keeping the anus does not guarantee normal bowel function. Ask about the likely outcome with each suitable operation.

Understanding and preparing for a stoma

A stoma brings a part of the bowel to an opening on the tummy. Stool collects in a pouch attached to the skin. An ileostomy is made from the small bowel; a colostomy is made from the colon. A stoma may be temporary or permanent.

A temporary ileostomy diverts stool away from a new bowel join while it heals. It reduces the impact of a leak but cannot prevent every leak. Reversal means closing the stoma and restoring the bowel route. It is considered only after healing and recovery; it is not guaranteed and has its own risks.

Meet a stoma nurse before surgery where possible. They can help choose the site, show you a pouch and discuss clothing, bathing, supplies and help at home. The team also checks nutrition, anaemia, medicines, exercise and smoking before the operation.

An ileostomy usually produces more liquid stool than a colostomy. Losing too much fluid can cause dehydration and affect the kidneys. Your nurse will explain how much output is expected and what to drink. Persistent pouch leakage or sore skin needs review; changing the fit or treating a nearby skin or bowel problem can help.

What treatment before surgery aims to do

Treatment before surgery can shrink cancer away from the planned cut edge, reduce the chance of it returning in the pelvis and treat cancer cells elsewhere that are too small to see. It also shows how the tumour responds. For selected patients, a complete clinical response may allow discussion of close monitoring instead of immediate surgery, within an experienced specialist programme.

Treatment and response checks take place before surgery, so the operation happens later. Cancer can sometimes grow despite treatment, and response tests have limits. The team monitors you and reviews the plan if symptoms or results change.

Two ways of giving radiotherapy

The choice depends on the tumour's position, how much it needs to shrink, your health and the rest of the treatment plan.

Radiotherapy may cause loose stools, urgency, tiredness, sore skin or irritation when passing urine. Effects can continue or temporarily worsen after the course ends. Some bowel, bladder and sexual changes can last longer. Careful positioning and planning limit exposure of healthy tissue but cannot remove every risk.

Before pelvic treatment, discuss any wish to have children. Options may include storing sperm, eggs or embryos. For some people, moving the ovaries away from the radiation area may be considered. Radiation can affect fertility, cause an early menopause, or contribute to vaginal dryness or narrowing and difficulty with erections.

Chemotherapy before surgery

Chemotherapy travels around the body through the bloodstream. A cycle is a period of treatment followed by time to recover. Ask which medicines you will receive, how many cycles are planned and when the response will be checked.

Ask about testing for low levels of dihydropyrimidine dehydrogenase (DPD), an enzyme that helps break down fluorouracil and capecitabine. This may include testing the DPYD gene, which provides instructions for making the enzyme. Low activity can cause severe side effects and may require a different dose or treatment.

Oxaliplatin can cause tingling, numbness or sensitivity to cold, called neuropathy. Report symptoms before they interfere with walking, buttons or other everyday tasks. Reducing the dose or stopping one medicine may protect long-term function while the rest of treatment continues.

Checking the response and deciding what comes next

Restaging means reassessing the cancer after treatment. The team brings together symptoms, a gloved-finger rectal examination, a camera examination, pelvic MRI and checks for cancer elsewhere. CEA may help if it was raised before treatment.

No single test can show whether every cancer cell has gone. Scar tissue can still look or feel abnormal. A surface biopsy may miss deeper cancer, and small deposits may be invisible on scans.

What watch-and-wait means

For carefully selected patients with a confirmed complete clinical response, a specialist team may discuss watch-and-wait: regular, planned checks while deferring surgery. It is not a recommendation for everyone to avoid surgery. The decision includes the benefits and risks of surgery, your priorities and whether intensive follow-up is practical for you.

This can avoid a major operation and a possible permanent stoma, but cancer too small to detect may remain. Cancer can grow back in the rectum, most often within the first two years. Surgery is often possible if regrowth is found early, but a successful later operation cannot be guaranteed. Some patients then need an operation with a permanent stoma.

Follow-up usually includes frequent rectal and camera examinations, repeated pelvic MRI, CEA tests and CT scans. Checks for distant spread are still needed. The team should give you a written schedule and a route for prompt assessment of new bleeding, pain or bowel changes.

What the operation results mean

The pathologist examines the removed rectum and nodes to check how much cancer remains and whether the cut edges are clear. The report also assesses the quality of the removed surrounding tissue. These findings help estimate the chance of cancer returning.

A complete pathological response means no cancer is found in the tissue examined after treatment and surgery. This is encouraging, but follow-up remains necessary. It is different from a complete clinical response, which is judged using examinations and scans without removing the rectum.

More chemotherapy after surgery is not automatic after completed TNT. The decision depends on treatment already given, the operation results, recovery and side effects. If you have a temporary stoma, discuss the checks and timing needed before reversal.

Medicines when rectal cancer has spread

Biomarkers are features of cancer cells that can help select treatment. These include gene changes and proteins measured in the tumour. Your earlier medicines, current symptoms, general health and other test results also matter.

Another chemotherapy combination is folinic acid, fluorouracil and irinotecan (FOLFIRI). It does not contain oxaliplatin. The team chooses a combination and may add a targeted medicine, which acts on a particular cancer growth signal.

Treatment directed at liver, lung or pelvic cancer

If cancer has spread to a limited number of sites, specialists assess whether all visible cancer can be removed or destroyed. Options may include surgery, ablation using heat or cold, or precisely targeted radiation. Medicines may come before or after these treatments.

For cancer returning in the pelvis, another operation may involve nearby organs, such as the bladder, reproductive organs or part of the lower spine. Radiation to a previously treated area needs especially careful planning. These choices require a clear discussion of cancer control, recovery and lasting effects on daily life.

Ask the team to explain the plan for both the rectal tumour and every area of spread, when scans will be repeated, and what would make the treatment plan change.

Managing side effects

Bowel changes after rectal surgery

After part of the rectum is removed and the bowel is joined again, it may not store stool or control emptying as before. A group of symptoms called low anterior resection syndrome (LARS) can include urgency, frequent trips to the toilet, leakage and difficulty emptying fully. Several bowel movements close together are called clustering.

These symptoms can affect travel, sleep and confidence. They often improve over time, but you do not have to manage them alone. Ask for a bowel-function assessment and a treatment plan.

The team also checks for treatable causes, including infection, inflammation, medicine effects or a return of the cancer. Sometimes bile salts irritate the bowel and cause diarrhoea; treatment can help. Persistent symptoms should not automatically be accepted as an unavoidable result of surgery.

Bladder, sexual health and fertility

Pelvic surgery and radiotherapy can affect nearby nerves, blood vessels and organs. Mention changes early, even if they feel difficult to discuss. Help is available.

• Bladder problems: report difficulty emptying, leakage or repeated infections. A bladder specialist or pelvic-floor therapist may help. Being unable to pass urine needs urgent assessment.
• Erections and ejaculation: treatment can affect both. Medicines, devices and specialist support may help with erections; ejaculation and fertility need separate discussion.
• Vaginal dryness or discomfort: moisturisers, lubricants and, when suitable, hormone treatment may help. The team may recommend vaginal dilators, smooth devices used gently to help prevent or manage narrowing.
• Fertility and menopause: ask about storing sperm, eggs or embryos before treatment if relevant. Treatment can cause an early menopause, and support is available for its symptoms.

A caregiver or partner can join these discussions if you want, but you can also ask to speak privately. Recovery is individual, and support may still help months or years after treatment.

Live well

Eating, activity and emotional support

A dietitian can help if you are losing weight, struggling to eat, avoiding food because of bowel symptoms or managing a stoma. Food and fluid advice may change during treatment and recovery. An ileostomy that produces a lot of liquid needs an individual fluid and salt plan.

Build up activity gradually, following the surgical team's advice about lifting and wound healing. Small amounts of regular movement may be easier than a single long session. Ask for help with fatigue, sleep or pain that limits activity.

Worry about recurrence, changes in body image and difficulties with intimacy are common. A specialist nurse, counsellor or support group may help. Caregivers also need rest, information and support; sharing practical tasks can make treatment easier to manage.

Follow-up after treatment

Follow-up checks recovery, helps manage lasting effects and looks for signs that cancer has returned. Surveillance is another word for these planned checks. Your schedule may include appointments, CEA blood tests, scans and colonoscopy. The timing depends on your stage, treatment and individual risk.

Watch-and-wait requires especially close follow-up with rectal examinations, camera tests and MRI, as well as checks elsewhere in the body. Keep appointments even if you feel well. If attending becomes difficult, contact the team so they can help you keep to the plan.

Report new bleeding, persistent pain, a lasting change in bowel habits or unexplained weight loss between appointments. Do not wait for the next scheduled scan. Keep your treatment summary and the team's contact details somewhere you and your caregiver can find them.

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Meet our doctors

Dr (Prof) Vijay Agarwal

Professor and Lead Consultant – Medical Oncology

Dr Prathyush V

Senior Consultant – Medical Oncology & Haemato-Oncology

Dr Darshan R S

Consultant – Medical Oncology & Haemato-Oncology

Where to get care

Bannerghatta Road

Apollo Hospitals
Bengaluru

Seshadripuram

Apollo Hospitals
Bengaluru

Sarjapur

Apollo Hospitals
Bengaluru

Jayanagar

Apollo Speciality Hospital
Bengaluru