Medical Oncologist
CION Cancer Clinics
Which operation for which part of the colon? | CION Cancer Clinics
The operation you need depends mainly on where in the colon the tumour sits. A tumour on the right side usually means a right hemicolectomy, one in the sigmoid usually means a sigmoid colectomy, and the bends and middle of the colon need longer operations. The reason is the blood supply, which carries the lymph nodes. This page maps each location to its usual operation and explains what changes afterwards. At CION Cancer Clinics, a multidisciplinary team plans colon cancer treatment for your stage, from surgery to chemotherapy and follow-up.
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Medically reviewed by Dr. Muralidhar MuddusettyConsultant Surgical Oncologist · MBBS (AIIMS), MS (Surgery, AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh) · last reviewed October 2026, next review due October 2027
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On this page
- Why does the tumour's position decide the operation?
- Where is the tumour, and which operation is usual?
- What does each operation remove, and how does it change the bowel?
- How does the team find exactly where the tumour is?
- What do families often misunderstand about this?
- What this page cannot tell you
- Common questions about which colectomy you need
The short answer
Why does the tumour's position decide the operation?
The surgeon does not cut out just the lump. They remove the whole section of colon that shares the tumour's main blood vessels, because the lymph nodes, the small glands cancer spreads to first, run alongside those vessels. So the tumour's position decides which vessels are taken, and that decides which part of the colon comes out.
Each part of the colon has its own supply
The right side of the colon is fed by vessels from one main artery, and the left side and sigmoid by another. A tumour on the right means removing the right side with its nodes. A tumour in the sigmoid, the S-shaped last stretch before the rectum, means removing the sigmoid with its nodes. Our guide to the parts of the colon shows where each section sits.
Why not take less, or more?
Taking less risks leaving cancerous nodes behind and getting the stage wrong. Taking more than the vessels require does not improve the outcome for a single tumour, and it changes bowel habits more. The aim is the right amount, not the most.
The same logic applies whether the operation is done open, by keyhole or with a robotic system.Side by side
Where is the tumour, and which operation is usual?
Where the tumour is
The usual operation
Caecum or ascending colon, on the right
Right hemicolectomy
Hepatic flexure, the bend under the liver
Extended right hemicolectomy
Transverse colon, across the upper tummy
Extended right hemicolectomy or transverse colectomy
Splenic flexure, the bend near the spleen
Left hemicolectomy, extended right, or a segmental resection
Descending colon, on the left
Left hemicolectomy
Sigmoid colon, just above the rectum
Sigmoid colectomy
Two cancers apart, or an inherited syndrome
Subtotal or total colectomy may be discussed
Not sure whether this applies to you?
Ask an oncologistOperation by operation
What does each operation remove, and how does it change the bowel?
Your colon mainly absorbs water and stores stool. Losing a section rarely affects how you digest food, but it can change how often you open your bowels.
Right hemicolectomy
The surgeon removes the caecum, the ascending colon and the very end of the small bowel, then joins the small bowel to the transverse colon. Stools are often looser at first and usually settle. Our page on right hemicolectomy explains it in full.
Extended right or transverse colectomy
For tumours at the hepatic flexure or in the transverse colon, more of the colon goes, along with the vessels feeding the middle of it. Many surgeons prefer the extended right operation here, because the join tends to heal more reliably.
Left hemicolectomy and sigmoid colectomy
For the descending or sigmoid colon, that segment is removed and the colon is joined lower down. You may open your bowels more often for a while. Our page on left and sigmoid colectomy covers what to expect.
Subtotal or total colectomy
Most or all of the colon is removed. This is for two separate cancers, many polyps, or some inherited conditions. Stools are looser and more frequent afterwards. See our page on extended and subtotal colectomy.
Before the operation
How does the team find exactly where the tumour is?
The colonoscopy gives a first estimate
The endoscopist notes where the tumour seems to be. Inside a bendy colon this estimate can be wrong, especially in the middle sections, so it is never relied on alone.
A tattoo marks the spot
For smaller tumours, a little ink is injected into the bowel wall beside it. The surgeon can then see the mark from outside the bowel, including through a keyhole camera.
The CT scan confirms the position
A CT scan of the chest, abdomen and pelvis shows where the tumour sits, whether nodes look enlarged, and whether it touches another organ. If the colonoscope could not pass the tumour, the rest of the colon is checked another way.
The tumour board agrees the operation
Surgeons, radiologists and oncologists review the reports together. CION's surgical oncologists plan the operation and it is carried out at an accredited partner hospital.
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Commonly believed
What do families often misunderstand about this?
"Removing more colon is always safer."
For a single tumour, removing the segment with its vessels and nodes is enough. Taking more does not lower the chance of cancer returning, and it leaves you with looser, more frequent stools. Bigger operations are kept for specific reasons.
"Without part of the colon, you cannot digest food properly."
Food is digested and absorbed in the small bowel, which is kept. The colon mainly takes back water. Most people return to rice, dal, curd and their usual meals once the bowel settles.
"The surgeon only needs to cut out the lump."
The nodes that drain the tumour must come out with it. Checking them is how the stage is set, and the stage decides whether chemotherapy is advised afterwards.
"Right-sided and left-sided cancers are the same disease."
They behave differently, cause different symptoms, and can respond differently to some drugs. Right-sided tumours often bleed unseen and show up as anaemia, a low haemoglobin, rather than visible blood.
Being straight with you
What this page cannot tell you
It cannot tell you which operation you will have. The table above shows the usual choice, but your surgeon also weighs the tumour's size, whether it is stuck to another organ, your fitness and your earlier operations. Two tumours in the same place can need different operations.
Who this page does not apply to
It does not apply to cancer in the rectum, the last part of the bowel, where the operations, the use of radiation and the chance of a stoma are different. A tumour where the sigmoid meets the rectum sits on that border. Our page on colon versus rectal cancer explains how that is settled. It also does not cover very early cancers removed whole during colonoscopy.
The grey zones are genuinely debated
For tumours in the transverse colon or at the splenic flexure, there is no single standard operation. Surgeons choose based on the blood supply and the evidence they trust. Asking why one was chosen is reasonable.
If you want the planned operation checked against your scans, a second opinion is a normal request.Questions we are asked
Common questions about which colectomy you need
Which colectomy is the most common for colon cancer?
Right hemicolectomy and sigmoid colectomy are among the most common, because many colon cancers start on the right side or in the sigmoid. Which one you need depends only on where your tumour sits, confirmed by colonoscopy and CT scan.
How much of my colon will be removed?
Enough to take the tumour, its blood vessels and the lymph nodes along them. For a right or left hemicolectomy that is roughly one side of the colon. For a sigmoid colectomy it is the S-shaped last stretch. Your surgeon can show you on a diagram.
Will I need a stoma after a right or left hemicolectomy?
Usually not. In a planned operation the two ends are normally joined straight away. A stoma becomes more likely in an emergency, when the bowel is blocked or torn, or if the surgeon judges the join unsafe to heal on its own.
Why does my report say extended right hemicolectomy?
Because the tumour is near the hepatic flexure or in the transverse colon. Those areas share vessels with the middle of the colon, so more of it has to come out to remove the right nodes. It is the standard choice for that position, not a sign of worse cancer.
What if the colonoscopy and CT disagree about the location?
The surgeon relies most on the CT and on any tattoo left at colonoscopy. If the position is still unclear, a repeat colonoscopy to place a tattoo, or a check at the start of the operation, settles it before any bowel is removed.
I have Lynch syndrome. Should more of my colon come out?
Sometimes. Because the risk of a second colon cancer is higher, a bigger operation may be discussed, especially for younger patients. It is a trade-off against looser, more frequent stools. The decision is made with your surgeon and a genetic counsellor.
Does the location change whether I need chemotherapy?
Not directly. Whether chemotherapy is advised after surgery depends mainly on the stage, set by the pathology report. Location can matter later if the cancer spreads, because right and left tumours can respond differently to some targeted drugs.
Can CION do this operation?
CION's surgical oncologists review your scans, plan the operation with the tumour board, and it is carried out at an accredited partner hospital. Chemotherapy and follow-up then continue at a CION centre. Call the helpline to start.
Your Specialists
Meet CION's colon cancer specialists. Bring your colonoscopy, scan or biopsy report.
Our surgical and medical oncologists plan colon cancer care together: which operation, whether chemotherapy is needed, and the follow-up that comes after.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
Surgical Oncologist
Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
Surgical Oncologist
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Sources
- American Cancer Society — Colon Cancer Surgery
- National Cancer Institute — Colon Cancer Treatment
- Cancer Research UK — Treatment for bowel (colorectal) cancer
- American Cancer Society — What Is Colorectal Cancer?
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Surgery for colon cancer: what your options areThe full range of surgical options in one placeParts of the colon and why location mattersA plain map of the colon's sectionsHow much colon will be removed?What the length removed means for daily lifeTypes of colectomyThe operations themselves, step by step
Talk to us
Not sure why this operation was chosen for you?
Share your colonoscopy and CT reports and a CION surgical oncologist will explain which operation fits the tumour's position and why. If a second opinion would help, we will arrange the review. One helpline serves every CION centre.