Procedure
BUILD NOTE: this page was drafted for the refresh and has NOT yet been read by Dr Chen. Clinical content, and the medical-review byline above, must be confirmed by him before the domain cutover.
Surgery is the main treatment for colorectal cancer that has not spread beyond the bowel and nearby lymph nodes. The diseased section of the colon or rectum is removed, along with the nearby lymph glands, to reduce the risk of the cancer spreading.1 A margin of healthy bowel is taken on either side, and the bowel is rejoined where possible.
Before surgery you will usually have a colonoscopy with biopsy to confirm the diagnosis, and scans to establish the stage of the cancer. Chemotherapy or radiotherapy may be used before or after surgery, and for cancer in the rectum either is sometimes given beforehand to shrink the tumour.1 Your case should be assessed by a multidisciplinary team of specialists, who agree on the treatment plan together. Our guide to colorectal cancer covers the condition.
Staging establishes how far the cancer has spread before surgery is planned. It determines the operation, and whether any treatment should come first. The tests used include colonoscopy and biopsy, CT scanning and, in some cases, PET scanning.1 The sequence is usually:
Staging describes how deeply the cancer has grown into the bowel wall and whether it has reached the lymph nodes or other organs. The scans give a provisional stage, which is confirmed once the removed bowel and lymph nodes have been examined under the microscope. The decision about chemotherapy is made once that result is available.
An additional scan is required for rectal cancer. The rectum sits in a confined space close to other structures, which leaves smaller surgical margins and requires more precise planning.
BUILD NOTE: the CT, MRI and CEA detail above is standard practice but is not stated on the NCCS page, which lists only CT and PET among its diagnostic methods. Dr Chen to confirm the workup he uses before cutover.
| Operation | What is removed |
|---|---|
| Right hemicolectomy | The right side of the colon, for cancer in the caecum or ascending colon |
| Left hemicolectomy | The left side of the colon, for cancer in the descending colon |
| Sigmoid colectomy | The sigmoid colon, the S-shaped segment before the rectum, for cancer in that segment |
| Anterior resection | The upper or middle rectum, for cancer high enough that the anus can be preserved and the bowel rejoined |
| Abdominoperineal resection | The rectum and anus, for cancer very low in the rectum; requires a permanent stoma |
Many colorectal cancer operations can be performed laparoscopically, through several small incisions using a camera, rather than through one long incision. It has been shown to reduce pain after surgery and speed up recovery, though it is not suitable for every case.1 The principles of cancer clearance are the same either way.
Not every case is suitable. Large tumours, previous abdominal surgery with extensive scarring, or particular anatomy may make open surgery the safer choice, and an operation that begins laparoscopically is sometimes converted to open during the procedure if that is safer. Dr Chen will discuss which approach he expects to use and why.
A stoma is an opening on the abdomen through which the bowel empties into a bag. It allows waste to leave the body when the normal route cannot be used or has had to be removed, and it may be temporary or permanent.1 Many people having colorectal cancer surgery do not need one.
A temporary stoma is sometimes formed to protect a new join while it heals, particularly in rectal surgery, and is usually reversed in a second, smaller operation some months later. A permanent stoma is generally necessary only when the anus and its sphincter muscles have to be removed, as in an abdominoperineal resection for a very low rectal cancer. If a stoma is likely or possible in your case, Dr Chen will tell you before the operation and you will meet a stoma nurse beforehand.
The stoma nurse marks the site on your abdomen while you are sitting, standing and lying, so that the bag sits clear of your waistband, and goes through the practical routine with you before the operation.
Day to day, a stoma is managed by emptying and changing the bag, protecting the surrounding skin, and learning which foods make output thicker or looser. Most people find the first few weeks the hardest and become competent faster than they expect. A temporary stoma is reversed once the join has healed and any chemotherapy is complete. The timing is usually measured in months.
BUILD NOTE: stoma reversal timing and the stoma-nurse pathway are described here in general terms and are not covered by the NCCS source. Confirm with Dr Chen what applies at Mount Alvernia, and who provides stoma nurse support.
Most people stay in hospital for several days, with keyhole surgery usually at the shorter end of that range. You will be encouraged to sit up, walk and start drinking early, since some movement after surgery helps recovery. Bowel function takes time to recover. After rectal surgery in particular, stools are commonly more frequent or more urgent for a period before improving.
Early mobilising and early drinking are part of an approach known as enhanced recovery, which replaced the older practice of prolonged bed rest and fasting after abdominal surgery. It involves shorter fasting before the operation and careful fluid management during it. Drains and tubes are avoided where they are not needed, pain control does not rely wholly on strong opioids, and patients are helped out of bed and eating on the first day.
You will be asked to do more, sooner, than after older approaches. Sitting out of bed on the day of surgery and walking the corridor the next morning reduces chest complications and blood clots, and helps the bowel start working again. The nursing team will pace it with you.
BUILD NOTE: the enhanced recovery description is generic and carries no citation. Confirm with Dr Chen which elements apply at Mount Alvernia so this reflects what patients will actually experience.
BUILD NOTE: confirm typical length of stay and recovery timeframes with Dr Chen.
This is the part patients are least often warned about and most often troubled by. When the rectum is removed and the bowel rejoined, the reservoir that used to hold stool before you were ready is gone or much reduced. Bowel movements can then be more frequent, more urgent and grouped together over a period, and it can be harder to tell wind from stool.
This is common and generally improves over months as the bowel adapts. Measures that help include a regular eating pattern, bulking agents to give the stool more form, medication to slow transit where appropriate, and pelvic floor exercises.
Treatment is available. If symptoms are not improving, do not hesitate to raise it at a follow-up appointment.
BUILD NOTE: this section describes low anterior resection syndrome without naming it, and carries no citation because no Singapore patient-facing source was found covering it. Dr Chen to confirm the wording and whether he wants the clinical term used.
The removed tissue is examined under a microscope. This confirms the stage of cancer present, which the scans estimated before surgery, and determines whether chemotherapy is recommended afterwards. For stage 2 and stage 3 cancer, chemotherapy is usually given after surgery for three to six months, to reduce the risk of the cancer returning.1
You are then followed up for 5 years, with regular examinations, blood tests and scans, plus colonoscopies as needed.1 The usual pattern for colonoscopy is at 1 year, 3 years and 5 years after surgery, then every 3 years, where the colon was fully examined before treatment.2
What you pay depends on the operation, the length of stay and your insurance cover. MediSave can be used for hospitalisation and for approved day surgery, meaning a procedure on MOH’s Table of Surgical Procedures.3 An Integrated Shield plan may cover a substantial part of the cost. Our clinic will help you understand your position and give you a written estimate before you decide.
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This is major surgery and Dr Chen will go through the risks with you in detail in the context of your own health before you begin treatment. They include bleeding, infection, chest and urinary complications, blood clots, leakage from the join in the bowel, and injury to nearby structures. Effects on bowel, bladder or sexual function are also possible, and are more relevant in rectal surgery. The likelihood of each depends on the operation, your general health and the position of the tumour.
Many people having colorectal cancer surgery do not need one. A temporary stoma is sometimes used to protect a new join while it heals, particularly in rectal surgery, and is usually reversed later. A permanent stoma is generally needed only when the anus and sphincter muscles have to be removed. Dr Chen will tell you beforehand if a stoma is likely in your case.
Many colorectal cancer operations can be done laparoscopically, which has been shown to reduce pain after surgery and speed up recovery, though it is not suitable for every case.1 Suitability depends on the tumour, previous surgery and your anatomy, and an operation that starts as keyhole is occasionally converted to open if that is safer.
That is decided after surgery, once the removed tissue has been examined and the stage of cancer is confirmed. Some people need no further treatment; others are recommended chemotherapy. For rectal cancer, treatment before surgery is sometimes given instead. The plan is normally agreed by a multidisciplinary team.
Most people stay in hospital for several days and continue recovering at home over the following weeks, with keyhole surgery generally at the shorter end. Bowel function takes time to recover, particularly after rectal surgery. Dr Chen will provide a timeframe based on the operation you are having.
Staging usually involves a colonoscopy with biopsy to confirm the diagnosis and locate the tumour, and a CT scan of the chest, abdomen and pelvis. For rectal cancer, an MRI of the rectum is added. CT and PET scanning are both used.1 A blood test called CEA is often taken as a baseline. The stage of cancer present is confirmed from the removed tissue after surgery.
Because early movement and early feeding reduce chest complications and blood clots and help the bowel start working again. This approach, known as enhanced recovery, replaced the older practice of prolonged bed rest and fasting. The nursing team will pace it with you.
Once the join has healed and any chemotherapy is complete. The timing is usually measured in months. Reversal is a second, smaller operation. A stoma may be temporary or permanent,1 and a permanent one is generally needed only when the anus and sphincter muscles have to be removed.
They usually change. When the rectum is removed, the reservoir that held stool is gone or reduced. Bowel movements can then be more frequent, more urgent and grouped together, and it can be harder to tell wind from stool. This is common, and generally improves over months as the bowel adapts. Treatment is available, so do not hesitate to raise it at a follow-up appointment.
BUILD NOTE: every sourced statement on this page carries a numbered citation. All three sources were fetched and checked on 22 September 2026. The NCCS page shows no review date. The named operations in the table above, the risk list and the stoma reversal timing are not covered by any of these sources and carry no citation, so Dr Chen needs to confirm that wording himself at medical review. This page also makes no claim about cure or survival rates, which is deliberate.
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