Understanding Cancer

Bowel & Colon Cancer

New Zealand has one of the highest rates of bowel cancer in the world.

What to expect before, during, and after radiotherapy treatment:

Explore The Patient Pathway

Most bowel cancers start as benign growths on the wall of the bowel or small intestine. These are called polyps and look like small spots or cherries on stalks. Most are not cancerous, however, one type of polyp, an adenoma can become malignant and can form a tumour in the bowel glands.

Once cancer cells are in the wall, they can travel into the bloodstream or lymph nodes; from here the cancer cells can travel to other parts of the body. The most common places for bowel cancer cells to spread to are the liver and the lungs.

There are a few very rare bowel cancers. Some are very slow growing, and most need a different treatment to more common bowel cancer.

In more detail

By far the most common bowel cancer, adenocarcinomas originate in the glands that line the bowel wall. These glands produce the mucus that allows digested matter to pass easily through the large intestine and out of the body. Adenocarcinomas make up about 95% of all bowel cancers. There are some rare variations to this type, mucinous tumours and signet ring tumours, but the treatment is the same as for standard adenocarcinomas.

Other varieties of cancer that attack the bowel and colon include squamous cell carcinomas, which start in the skin-like lining of the bowel. There are also sarcomas which are cancers of the smooth muscle that supports the bowel, and carcinoid tumours, slow growing cancers of hormone-producing tissue.

Lymphomas are the most rare - they account for about 1% of all bowel cancers. They usually attack the lymph nodes. Each of these cancers has a unique behaviour pattern and growth rate and require treatment that is quite different to the more common adenocarcinomas.

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The Patient Pathway

First Specialist Appointment

At the first specialist appointment you will meet with your specialist radiation oncologist (RO) to discuss the proposed radiotherapy treatment approach and answer any questions and concerns you may have. Click read more to learn more and download information by treatment site e.g. breast, prostate.


At the orientation appointment a patient care specialist (nurse or radiation therapist) will explain the procedures in more detail and answer any concerns that you might have about ARO and your treatment. Click read more to learn more and download information by treatment site e.g. breast, prostate.


Before starting treatment, you will attend a simulation appointment to determine the optimal body position for receiving treatment and provide a detailed picture of the area to be treated.

First Day of Treatment

Please arrive 10-15 minutes before your allocated treatment time so we can greet you and allow you time to get changed for your treatment. Please bring an extra layer of clothing (e.g. cardigan or jacket) should you feel cold while you wait in the treatment reception area. Please report to the ARO reception desk. For free parking please refer to the information below. See location and parking for more information.

During Treatment

Weekly reviews with your radiation oncologist or one of our patient care team will be conducted to monitor any side effects and provide on-going support and advice as required. Click read more to learn more and download information by treatment site e.g. breast, prostate.

Last Week of Treatment

An appointment will be scheduled for you to meet with a member of our patient care team to answer any questions and to ensure appropriate care is organised after your last treatment visit. This may include regular monitoring of blood results, appointments for dressings and management of side effects.

After Treatment

Usually 2-6 weeks after your last treatment visit you will meet with your radiation oncologist or the doctor that referred you to ARO. Your GP will also be sent a report about your treatment and will continue to provide for your general health needs. 

You are welcome to contact our patient care team to answer questions or concerns that you may have about your treatment or possible side effects up to 2 weeks following your last treatment visit.  Please phone our nurses on 09 623 6585, email aronurses@aro.co.nz or make an appointment during business hours. 

Should you require support after 2 weeks, please contact the ARO Specialist Centre on phone 09 623 6587 or email specialistcentre@aro.co.nz. For all other health concerns, please contact your GP, usual healthcare provider or local emergency facility. Click read more to learn more and download information by treatment site e.g. breast, prostate. This includes information on possible side effects and self care advice by treatment site.