Gastrointestinal cancer treatment depends on where the tumour started, what the biopsy shows, and whether the cancer has spread. Most localised colon cancers are treated with surgery first, while many locally advanced rectal cancers need treatment before surgery. In oesophageal and gastric cancers, the tumour’s location, subtype, and stage guide whether treatment starts with endoscopic removal, surgery, chemotherapy, or chemoradiation. For advanced disease, molecular testing can help identify when immunotherapy or targeted therapy is appropriate. [1–5]
By Dr Raman Narang, Consultant Medical & Hemato-Oncologist, New Delhi
“Can we remove it?” is often the first question after a gastrointestinal cancer diagnosis. The next question is just as important: what should happen before or after the operation? A tumour in the colon and one a short distance away in the rectum can require a different sequence. This guide covers four common digestive tract cancers for patients and families reviewing their options for gastrointestinal cancer treatment in Delhi.
1. What symptoms should prompt assessment, and how are GI cancers diagnosed?
| Where the cancer starts | Symptoms that may prompt investigation | Usual test to confirm the diagnosis |
|---|---|---|
| Oesophagus (food pipe) | Progressive difficulty swallowing, painful swallowing, or unexplained weight loss | Upper gastrointestinal endoscopy with biopsy |
| Stomach (gastric cancer) | Feeling full after a small meal, persistent upper abdominal discomfort, vomiting, or iron-deficiency anaemia | Upper gastrointestinal endoscopy with biopsy |
| Colon | Blood in the stool, persistent changes in bowel habits, unexplained iron-deficiency anaemia, or abdominal discomfort | Colonoscopy with biopsy |
| Rectum | Rectal bleeding, a change in bowel habits, or a persistent feeling of needing to pass stool even after going to the toilet | Colonoscopy or sigmoidoscopy with biopsy, with assessment of the rest of the colon when feasible |
These symptoms can have several causes. New or worsening difficulty swallowing, persistent rectal bleeding, or unexplained iron-deficiency anaemia deserves assessment. Vomiting blood, heavy rectal bleeding with faintness, or severe abdominal pain with vomiting and inability to pass stool or gas warrants urgent medical care. [1, 2, 5]
Once a biopsy confirms cancer, staging scans assess whether it is confined to its starting site, involves nearby tissues or lymph nodes, or has spread to distant organs. The next test depends on the site. A dedicated pelvic MRI is central to rectal cancer planning. Selected patients with apparently operable gastric cancer may need staging laparoscopy to look for small deposits on the abdominal lining that were missed on CT. [1, 2, 4, 5]
2. How is oesophageal cancer treated?
The two main types are squamous cell carcinoma and adenocarcinoma. Squamous cell carcinoma can arise anywhere in the oesophagus and often occurs in its upper or middle portion. Adenocarcinoma usually starts lower down, sometimes at the junction with the stomach. The biopsy subtype can change which treatment comes first. [1]
- Very early disease. Selected superficial tumours can be removed through an endoscope. The removed tissue is examined for depth, clear margins, and features that suggest a risk of lymph node spread.
- Locally advanced disease. For many fit patients with resectable adenocarcinoma of the oesophagus or its junction with the stomach, perioperative FLOT chemotherapy is given before and after surgery. For suitable patients with locally advanced squamous cell carcinoma, chemoradiation followed by surgery is one option. Definitive chemoradiation, with no planned operation afterward, is also used in selected cases, including some cancers high in the oesophagus.
- Metastatic disease. Treatment usually starts with medicines. The subtype and biomarkers, such as PD-L1 and, for appropriate adenocarcinomas, HER2, can affect the choice. Swallowing and nutrition may need a separate plan while treatment takes effect. [1]
3. How is gastric cancer treated?
Most stomach cancers are gastric adenocarcinomas. The team considers how deeply the tumour has grown, whether nearby lymph nodes are involved, and whether the stomach can be partly preserved. For selected patients, staging laparoscopy and peritoneal washings can find cancer on the abdominal lining even when CT shows no visible spread. That result can change a planned operation. [1, 2]
- Very early or localised disease. Selected tumours confined to the inner lining can be removed endoscopically. Other early cancers may need surgery first, with removal of part or all of the stomach and nearby lymph nodes.
- Resectable, locally advanced disease. Many patients receive chemotherapy before and after surgery. FLOT is one option for patients fit enough to receive it. If surgery has already been done, the final stage, margins, and lymph node findings guide whether postoperative chemotherapy is appropriate.
- Unresectable or metastatic disease. Systemic treatment is usually the main approach. Depending on the setting, HER2, PD-L1, MSI/MMR, and CLDN18.2 testing can inform the use of targeted therapy or immunotherapy. Symptoms such as bleeding, vomiting, or difficulty eating may need treatment alongside cancer therapy. [1, 2]
4. How is colon cancer treated?
Most patients with localised colon cancer have surgery first. A colectomy removes the affected segment of colon and nearby lymph nodes. The surgical pathology then shows whether chemotherapy is likely to reduce the risk of recurrence. [3]
| Stage or situation | What usually guides treatment |
|---|---|
| Stage I | Surgery is usually sufficient. Some very early cancers removed in a polyp can be managed endoscopically when the pathology shows complete removal and favourable features. |
| Stage II | Many patients need follow-up alone after surgery. Chemotherapy may be discussed if the tumour reached the outer surface of the colon, grew into nearby structures, caused obstruction or perforation, or showed other higher-risk features. MMR/MSI results also inform the decision. |
| Stage III | Chemotherapy after surgery is generally recommended for patients fit enough to receive it. The regimen and duration depend on recurrence risk and expected side effects. |
| Stage IV | The team assesses whether all known sites of disease can be treated locally. Selected patients with limited liver or lung metastases may be considered for surgery or ablation. More widespread disease usually starts with systemic treatment. |
For metastatic colon cancer, MMR/MSI, KRAS, NRAS, and BRAF results can guide treatment. The side of the colon where the cancer started can also influence the choice of certain targeted drugs. [3, 6]
5. How is rectal cancer treated, and when is treatment given before surgery?
A dedicated rectal MRI shows how low the tumour sits, how close it is to the muscles that control bowel movements, and whether it approaches the expected surgical margin. Those details help determine whether to operate first, give treatment first, or consider an organ-preserving approach. [4, 5]
- Early disease. Selected small, low-risk tumours can be removed through the anus. Other early rectal cancers need an operation that also removes the surrounding tissue and regional lymph nodes.
- Locally advanced disease. Many patients with low rectal tumours or higher-risk MRI findings receive total neoadjuvant therapy (TNT), which gives systemic chemotherapy and pelvic radiation before the planned operation. Some lower-risk tumours can be treated with a different sequence or with selective use of radiation.
- Biomarker-directed treatment and organ preservation. In locally advanced dMMR/MSI-high rectal cancer, immunotherapy may be the first treatment for eligible patients. For selected patients who have a clinical complete response on examination, endoscopy, and MRI, a structured watch-and-wait programme may allow them to defer surgery. It requires close follow-up because the tumour can regrow.
- Metastatic disease. Systemic therapy is often the first step. The team also considers whether limited metastases can be treated locally and whether the rectal tumour needs treatment for bleeding, pain, or obstruction. [4–6]
What I look for clinically before recommending treatment
I first confirm where the tumour is centred, especially when it sits at the oesophagus–stomach junction or near the boundary between the sigmoid colon and rectum. Then I look for the finding that could change the sequence: an MRI showing a threatened rectal surgical margin, a gastric cancer that needs staging laparoscopy, or a liver lesion that could change the goal of treatment. I also ask what needs attention now, such as poor intake, bleeding, or a possible blockage.
How the next step is decided
| If the reports show… | The next discussion is about… |
|---|---|
| A very superficial oesophageal or gastric tumour | Whether endoscopic removal can provide complete treatment |
| A resectable but locally advanced oesophageal or gastric cancer | Which treatment should come before surgery and why |
| A localised colon cancer | Surgery and which pathology results will determine the need for additional treatment |
| A low rectal cancer or a threatened surgical margin on MRI | Treatment before surgery, expected bowel function, and whether organ preservation is realistic |
| A few liver or lung metastases from colorectal cancer | Whether all sites can be treated and in what order |
What to bring to a gastrointestinal cancer consultation in Delhi
- Endoscopy or colonoscopy report, including the exact tumour location and any images.
- Biopsy or surgical pathology report and details for obtaining the slides or tissue block.
- CT, MRI, or PET-CT reports and the original scan images, if available.
- Operation notes or staging laparoscopy and peritoneal washings reports, if performed.
- Relevant biomarker reports and details of any previous chemotherapy, radiation, or immunotherapy.
- A note of recent weight changes, what you can eat, and any bleeding, vomiting, or bowel changes.
Frequently asked questions
Why might I need chemotherapy before surgery if the tumour can be removed?
For many locally advanced oesophageal, gastric, and rectal cancers, starting treatment before surgery can address microscopic disease and, depending on the site, improve local control or help achieve a clear surgical margin. The reason should be specific to your tumour and stage. [1, 2, 4, 5]
Why do colon and rectal cancers have different treatment plans?
The rectum sits in a narrow space in the pelvis, close to the sphincter muscles and other organs. MRI findings can make radiation or chemotherapy before surgery important. Most localised colon cancers proceed to surgery first. [3–5]
Does stage IV always rule out surgery?
Selected patients with colorectal cancer and limited liver or lung metastases may still be assessed for treatment with the aim of cure. The decision depends on whether all known disease can be treated and on the patient’s overall health. [3, 6]
Does everyone with a GI cancer need the same biomarker tests?
The useful tests depend on the tumour site, subtype, and stage. For example, HER2 and CLDN18.2 may guide treatment in advanced gastric adenocarcinoma, while MMR/MSI and RAS can inform decisions in colorectal cancer. [1, 2, 6]
Before starting treatment, ask your team to write down the exact cancer site, the stage, the goal of treatment, and the reason for choosing the first step. If two sequences are possible, ask what would make the team choose one and when that decision will be reviewed.
This page is for general education. Individual treatment decisions require review of your pathology, scans, symptoms, and overall health by your treating team.
Clinical references
- European Society for Medical Oncology. Gastric and Oesophageal Cancer: ESMO Clinical Practice Guideline for Diagnosis, Treatment and Follow-up.
- National Cancer Institute. Gastric Cancer Treatment (PDQ). Health Professional Version.
- National Cancer Institute. Colon Cancer Treatment (PDQ). Health Professional Version.
- American Society of Clinical Oncology. Management of Locally Advanced Rectal Cancer: ASCO Guideline.
- European Society for Medical Oncology. Localised Rectal Cancer: ESMO Clinical Practice Guideline for Diagnosis, Treatment and Follow-up.
- American Society of Clinical Oncology. Treatment of Metastatic Colorectal Cancer: ASCO Guideline.