Medical Oncologist
CION Cancer Clinics
Colon lymphoma, GIST and other rare colon cancers | CION Cancer Clinics
Most colon cancers are adenocarcinomas, which grow from the gland cells lining the bowel. A small number are something else: a lymphoma, a GIST, a sarcoma, or a cancer that began in another organ and spread to the colon. Each is treated differently, often without the surgery-then-chemotherapy plan used for ordinary colon cancer. This page explains what each type is, how it is confirmed and why the type changes the plan. At CION Cancer Clinics in Hyderabad, our oncologists explain colon cancer in plain words and plan care around you and your family.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed October 2026, next review due October 2027
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The short answer
What counts as a rare colon cancer?
Almost every cancer that starts in the colon is an adenocarcinoma, a cancer of the gland cells that line the bowel. A rare colon cancer is any tumour that starts from a different kind of cell. The commonest of these are lymphoma, which grows from immune cells in the bowel wall, and GIST, which grows from the cells that keep the bowel moving. Sarcomas, and cancers that spread to the colon from another organ, are rarer still.
Why the type changes everything
Ordinary colon cancer has a well-worn path: an operation to remove the affected segment, then chemotherapy for some people. A rare type may follow none of that. A colon lymphoma is usually treated with chemotherapy and an antibody drug, often without any operation. A GIST is removed by surgery and may then need a targeted tablet, while the standard colon cancer drugs do little for it. Getting the type right comes first, and it comes from the pathologist, not the scan.
Neuroendocrine tumours have their own page
Carcinoid and other neuroendocrine tumours are also uncommon in the colon. They have their own grading and their own treatments, explained on the neuroendocrine tumours page.
Rare does not mean untreatable. It means the plan must be built for that type, not borrowed from ordinary colon cancer.The main rare types
Lymphoma, GIST, sarcoma: what is each one?
Each starts in a different layer of the bowel wall, and each is treated by a different route.
Colon lymphoma
A cancer of lymphocytes, the immune cells that sit in the bowel wall. In the colon it most often appears near the appendix, where the small bowel joins the large bowel. Diffuse large B-cell lymphoma is the commonest kind.
Often shows up as
- A lump or thickening on a scan
- Fever, night sweats or weight loss
- Pain, bleeding or a blocked bowel
GIST
A gastrointestinal stromal tumour grows from the pacemaker cells that make the bowel squeeze. Most GISTs are in the stomach or small bowel, so one in the colon is unusual. They tend to spread to the liver rather than to lymph nodes.
Many GISTs carry a KIT gene change that a targeted tablet can block.Sarcoma
A leiomyosarcoma grows from the muscle layer of the bowel wall and is very rare. Many tumours given this name in the past would now be called GIST, which is why an old report and a new one can disagree.
Cancer that spread to the colon
Sometimes the tumour in the colon began elsewhere, often in the ovary, stomach or breast. Under the microscope it looks like the original cancer, and it is treated as that cancer, not as colon cancer.
Not sure whether this applies to you?
Ask an oncologistFrom biopsy to plan
How do doctors confirm a rare type?
A biopsy, at colonoscopy or by needle
CION arranges the colonoscopy or a needle biopsy through its partners. A tumour growing beneath the bowel lining can look normal from the inside, so the sample sometimes has to come from a scan-guided needle instead.
Special stains on the tissue
The pathologist uses stains that light up particular proteins. Lymphoma cells, GIST cells and sarcoma cells each carry their own markers. This is the step that separates a rare type from an ordinary adenocarcinoma, and it can add a few extra days.
Scans matched to the type
Lymphoma is usually staged with a PET-CT, and sometimes a bone marrow sample. A GIST or a sarcoma is usually staged with CT. CION arranges these through its imaging partners.
The tumour board and the right specialist
A lymphoma is led by a medical oncologist or haematologist. A GIST is led by a surgical oncologist, with a medical oncologist alongside. The tumour board agrees the order of treatment before anything starts.
Side by side
What usually comes first for each type?
The type
What usually leads treatment
Ordinary adenocarcinoma
Surgery, with chemotherapy afterwards for some stages
Lymphoma
Chemotherapy with an antibody drug; surgery mainly for a blockage or bleeding
GIST
Surgery, then a targeted tablet if the risk of return is high
Sarcoma
Surgery, with chemotherapy or radiation chosen case by case
Spread from another organ
Treatment aimed at the original cancer
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Commonly believed
Four things families say about rare colon cancers
"Rare means doctors here will not know how to treat it."
These types are uncommon, not unknown. Oncologists treat lymphoma routinely, and GIST treatment is well established. What matters most is an accurate pathology report and a tumour board that reviews it, and both can be arranged without leaving Hyderabad.
"A GIST is a harmless growth, so it can be left alone."
Some small GISTs behave gently, but any GIST can grow and spread. Its size, its site and how fast the cells are dividing decide the risk. That is a judgement for the surgical oncologist, not a reason to wait.
"If it is in the colon, the colon has to come out."
Not for lymphoma. Chemotherapy and antibody treatment often clear a colon lymphoma without an operation. Surgery is kept for a bowel that is blocked, bleeding or torn, or for when an operation was the only way to make the diagnosis.
"The same chemotherapy works for every bowel cancer."
The drugs used for ordinary colon cancer, such as FOLFOX, are chosen for adenocarcinoma. Lymphoma uses a different combination, and GIST barely responds to standard chemotherapy at all. This is why the type must be clear before treatment starts.
Being straight with you
What this page cannot tell you
It cannot tell you which type you have. Rare colon tumours can look the same on a scan and at colonoscopy, and only the pathologist's stains settle the question. If your report says suspicious, or asks for further tests, the type is not yet known, and no plan should start until it is.
It cannot predict how your tumour will behave
Within each type there is a wide range. A low-risk GIST removed completely and a GIST that has reached the liver are very different situations, and the same is true of lymphoma. Your oncologist will explain what the grade, the stage and the markers mean for you.
Who this does not apply to
If your report says adenocarcinoma, including the mucinous and signet ring cell types, you have one of the commoner forms and the usual colon cancer pathway applies. Tumours of the anus, including most squamous cell cancers and melanomas of the lower bowel, belong to the anal cancer hub. This page is written for adults; lymphoma in children follows a different plan.
For a second opinion, bring the pathology report, the biopsy blocks or slides and the scans on disc. A fresh look at the slides is often where a rare type is confirmed.Questions we are asked
Common questions about rare colon cancers
Is colon lymphoma the same as colon cancer?
Not quite. Lymphoma is a cancer of the immune system that happens to be growing in the colon. It is staged and treated as a lymphoma, usually with chemotherapy and an antibody drug, rather than with the operation-first plan used for ordinary colon cancer.
What exactly is a GIST?
A gastrointestinal stromal tumour, which grows from the cells that control the bowel's squeezing movements. It is a type of sarcoma, and in the colon it is rare. Surgery is the main treatment, and a targeted tablet is added when the risk of the tumour returning is high.
Can a GIST be treated with tablets alone?
Sometimes, for a time. A targeted tablet can shrink a large GIST before surgery or hold back one that has spread. Whether it works depends on the gene change inside the tumour, so the tissue is tested first. Surgery remains the main treatment whenever the tumour can be removed.
How are rare colon cancers usually found?
Mostly the same way as ordinary colon cancer: bleeding, pain, a change in bowel habit, anaemia (a low haemoglobin) or a blocked bowel leads to a scan or a colonoscopy. Some are found by chance on a scan done for something else entirely.
Are these cancers inherited?
Most are not. A few rare syndromes raise the risk of GIST, and a weakened immune system raises the risk of lymphoma, but most people have no family pattern. Your oncologist will ask about the family and suggest genetics advice only if something fits.
Will I need a stoma?
Not usually. When an operation is needed, the surgeon normally joins the two healthy ends of bowel together. A stoma is more likely after emergency surgery for a blocked or torn bowel. CION's surgical oncologists plan any operation, which is carried out at an accredited partner hospital.
Why is my biopsy report taking so long?
Rare types need extra stains, and sometimes a gene test on the tissue, before the pathologist can sign the report. A second review at a specialist laboratory is also common. The wait is worth it, because starting the wrong treatment would cost far more time.
Where do I start if my report names a rare type?
Collect the full pathology report, the slides or blocks if you can, and the scans on disc. Bring them to a medical oncologist. If you are unsure where to go, call the CION helpline and someone will book the right clinic and arrange any missing tests.
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 — What Is Colorectal Cancer?
- Cancer Research UK — Stages, types and grades of bowel cancer
- National Cancer Institute — Targeted Therapy for Cancer
- National Cancer Institute — Surgical Pathology Reports
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
Types of colon cancerWhere the rare types sit beside the common onesNeuroendocrine tumours of the colonIf your report says carcinoid or neuroendocrineSmall bowel cancer and how it differsWhere most bowel lymphomas and GISTs actually startSecond opinion on a colon cancer diagnosisHaving the slides looked at again before treatment
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Has your report named an unusual type of colon tumour?
Send us the pathology report and scans, and a medical oncologist will explain what the type means and what the next step should be. One helpline serves every CION centre.