Bowel cancer treatment depends on the type and stage of cancer, where it started and whether it has spread. Doctors also consider a person’s general health, test results and preferences before recommending treatment.
Treatment may include surgery, chemotherapy, radiotherapy, targeted medicines or immunotherapy. Doctors often combine several approaches. A specialist team reviews scans, biopsy results and other tests before agreeing on a treatment plan.
Bowel cancer treatment at a glance
- Surgery is an important treatment for many localised bowel cancers.
- Doctors may use chemotherapy before or after surgery, or to treat advanced disease.
- Doctors often use radiotherapy for some rectal cancers.
- Doctors may recommend targeted medicines or immunotherapy for some advanced cancers after tumour testing.
- Every treatment plan is different. The same approach does not suit every patient.
Important: this page gives general information about bowel cancer treatment. An oncology or colorectal specialist team should make decisions about diagnosis and treatment with the patient.
On this page
- How doctors plan bowel cancer treatment
- Surgery for bowel cancer
- Chemotherapy
- Radiotherapy and chemoradiotherapy
- Targeted medicines and immunotherapy
- Advanced or metastatic bowel cancer
- Research into probiotics and the microbiome
- Bacillus subtilis and interferon-related immune pathways
- Sodium bicarbonate and tumour acidity
- Colon hydrotherapy and bowel cancer
How doctors plan bowel cancer treatment
Bowel cancer includes cancers that start in the colon or rectum. These cancers are closely related, but doctors may treat them differently.
Doctors first look at the size and position of the tumour. They also check how deeply it has grown and whether cancer cells have reached nearby lymph nodes or other organs.
Tests can also identify changes within the tumour. These results may help doctors choose medicines that target particular features of the cancer.
For example, some people with rectal cancer receive radiotherapy or chemoradiotherapy before surgery. In contrast, some people with colon cancer have surgery first and chemotherapy afterwards.
The NICE colorectal cancer guidance explains how doctors choose treatment according to the tumour site, cancer stage and other clinical factors.
Surgery for bowel cancer
Surgery remains an important bowel cancer treatment when doctors can safely remove the tumour.
The surgeon usually removes the cancer together with a small area of healthy bowel and nearby lymph nodes. The surgeon may then join the remaining sections of bowel.
Some patients need a colostomy or ileostomy. This creates an opening in the abdomen so bowel contents can pass into a stoma bag. A stoma may be temporary or permanent, depending on the operation.
Surgeons may use open surgery or keyhole techniques. The surgical team will explain the planned procedure, possible risks and expected recovery before treatment begins.
Chemotherapy for bowel cancer
Chemotherapy uses anti-cancer medicines to destroy cancer cells or stop them from dividing.
Doctors may give chemotherapy before surgery to shrink a tumour. They may also recommend it after surgery to reduce the risk of cancer returning.
Chemotherapy can also help when bowel cancer has spread beyond the original site. In that situation, treatment may slow the cancer, ease symptoms and sometimes make other treatments possible.
Doctors choose the medicines according to the cancer type and stage, previous treatment and the patient’s general health.
The NHS overview of bowel cancer treatment explains the main options and when doctors may use them.
Radiotherapy and chemoradiotherapy
Radiotherapy uses high-energy radiation to damage cancer cells.
Doctors often use radiotherapy for some types of rectal cancer. They may use it alone or together with chemotherapy before surgery. This approach can lower the risk of the cancer returning in the same area.
Doctors use radiotherapy less often for colon cancer. However, it can sometimes help control symptoms when cancer has spread.
Targeted medicines and immunotherapy
Modern bowel cancer treatment increasingly takes account of the features of each tumour.
Targeted medicines interfere with specific processes that cancer cells use to grow. Some treatments only work when tests show certain changes in the tumour.
Immunotherapy helps the immune system recognise or attack cancer cells. Doctors may consider it for some advanced colorectal cancers with particular test results.
Therefore, tumour testing can become especially important when cancer has spread. Cancer Research UK explains targeted medicines and immunotherapy for metastatic bowel cancer.
Treatment for advanced or metastatic bowel cancer
Metastatic bowel cancer has spread from the colon or rectum to another part of the body. The liver and lungs are common sites, although cancer can spread elsewhere.
Treatment depends on where the cancer has spread and how much disease doctors can see. Doctors may still offer surgery to some patients. In other cases, chemotherapy, targeted medicines, immunotherapy or radiotherapy may help control the cancer.
The aim of treatment can differ. Sometimes doctors try to remove all visible cancer. At other times, treatment aims to slow its growth, ease symptoms and maintain quality of life.
See Cancer Research UK’s guide to metastatic bowel cancer treatment for further information.
Research update
Research into probiotics, the microbiome and bowel cancer
The relationship between gut bacteria and colorectal cancer is an active area of research.
Researchers reviewed nine controlled clinical trials involving people with a higher risk of bowel cancer. They studied probiotics, prebiotics and synbiotics.
In the combined results, people taking probiotics developed fewer colorectal adenomas. Adenomas are growths that can sometimes develop into cancer. However, the analysis did not find a significant reduction in colorectal cancer itself.
A later controlled study investigated the probiotic Clostridium butyricum MIYAIRI 588 in people who had previously developed colorectal adenomas. Some analyses suggested fewer recurring adenomas. However, the main comparison during the first year did not show a clear reduction.
Bacillus subtilis and interferon-related immune pathways
Bacillus subtilis is another probiotic species being studied for its effects on the immune system. One strain, Bacillus subtilis CU1, has been investigated in human clinical research.
In a 2024 clinical study, 88 participants took B. subtilis CU1 for four weeks. Researchers found changes in groups of genes involved in the type I interferon response and other parts of innate immunity.
When researchers later stimulated participants’ blood samples in the laboratory, they also found a stronger immune response involving several signalling molecules, including interferon-gamma (IFN-γ). The study therefore suggests that this particular strain can influence interferon-related immune pathways.
What has research found about Bacillus subtilis and colorectal cancer?
Laboratory and animal research has also explored whether probiotics such as Bacillus subtilis might influence colorectal tumour development.
A 2015 study examined B. subtilis together with Clostridium butyricum. In laboratory tests, the probiotics slowed the growth of colorectal cancer cells and promoted cancer-cell death. In mice with chemically induced colorectal cancer, the probiotics also reduced tumour development.
The researchers linked these effects to lower inflammation and improved immune balance. These findings provide an interesting basis for further research into probiotics and colorectal cancer prevention.
What this means: these studies show biologically interesting effects on immunity and tumour development, but they do not prove that Bacillus subtilis prevents bowel cancer in people. An immune response linked to interferon is also not the same as receiving interferon as a cancer medicine.
It is also important to distinguish between probiotic strains. Research on B. subtilis CU1 does not automatically apply to every product containing Bacillus subtilis. The NHS notes that different probiotics can have different effects and that evidence does not support every health claim made for probiotic supplements.
Overall, probiotic research in bowel cancer is promising but still developing. Probiotics should not replace bowel screening, colonoscopy, surgery, cancer treatment or medical follow-up.
Laboratory research
Sodium bicarbonate and tumour acidity: what does the research show?
Scientists have also studied the acidic environment that can develop around cancer cells.
A 2026 laboratory and animal study looked at how acidity around colorectal cancer cells may help tumours grow and resist treatment.
In one experiment, researchers gave sodium bicarbonate to mice with colorectal tumours to reduce acidity around the tumour. The treatment slowed tumour growth in this animal model.
Earlier animal research also looked at bicarbonate and the acidic environment around tumours. A 2009 study found fewer spontaneous metastases in mouse models of metastatic breast cancer.
What this means: these results come from laboratory and animal research. They do not show that taking sodium bicarbonate prevents or treats bowel cancer in people. They also do not show that bicarbonate used during colonic irrigation has an anti-cancer effect.
People receiving cancer treatment should therefore discuss supplements and complementary approaches with their medical team.
Colon hydrotherapy and bowel cancer
Colon hydrotherapy is not a treatment for bowel cancer and should not replace cancer screening or medical care.
If someone has possible bowel cancer symptoms, medical investigation takes priority. Anyone who has a cancer diagnosis, receives chemotherapy or radiotherapy, or has recently had bowel surgery should speak with their specialist team before considering complementary treatments.
Concerned about possible symptoms?
Read our separate guide to Colon Cancer Symptoms: Signs and When to See a GP. It explains common warning signs, FIT testing and when to seek medical advice.
Reliable information and further reading
Bowel cancer treatment changes as new evidence becomes available. For current medical advice, use information from specialist health organisations and discuss treatment with your clinical team.
- NHS: Treatment for bowel cancer
- NICE: Colorectal cancer – recommendations
- Cancer Research UK: Bowel cancer treatment
- PubMed: Probiotics, prebiotics and synbiotics research
- PubMed: Colorectal cancer and tumour acidity research
- PubMed: Bacillus subtilis CU1 and interferon-related immune responses
- PubMed: Bacillus subtilis, Clostridium butyricum and intestinal tumour research
- NHS: Probiotics – evidence and limitations
Medical information: this article is for general educational purposes. It does not replace assessment, diagnosis or treatment by a qualified medical professional.
