Rectal Cancer Treatment

Surgery for rectal cancer involves either a low anterior resection operation or an abdominoperineal excision operation. In most cases, this surgery results in the formation of a stoma bag. The difference is that with a low anterior resection, the stoma (ileostomy) is usually temporary and can be reversed a few months later once all treatment has been completed. An ‘abdominoperineal excision’ involves removal of the entire back passage, so this requires a permanent colostomy stoma.

The vast majority of people get used to having a stoma bag, and most hospitals have a stoma nurse to talk through how to get used to it and how to manage it. 

Radiotherapy for rectal cancer is performed when there is a concern that the tumour cannot be completely removed. If surgical resection margins are very close to the cancer, then the risk of tumour regrowth is much higher. The role of radiotherapy in rectal cancer is complex and should be discussed with your medical teams. A completely individualised approach based on your specific circumstances is essential.

Dr Andy Gaya has access to cutting edge cancer treatments including SABR (Stereotactic Ablative Body Radiotherapy). It is advantageous for patients with multiple metastatic sites where a few sites are not being managed by drug treatment, removing residual or resistant sites and allowing the patient to continue on drug treatment that is working to control the majority of their disease. Note that SABR is not always accessible on the NHS and is a development area.

If there is any concern that these margins may be close or involved, then preoperative chemoradiotherapy is offered. This is much more common for low rectal cancers as the fatty sheath surrounding the bowel (mesorectum) is much thinner in the low rectum.

Chemotherapy for rectal cancer can be used either before surgery (neoadjuvant chemotherapy), after surgical resection (adjuvant chemotherapy) or in the situation of advanced disease (stage IV rectal cancer) where the cancer has moved to other parts of the body. Chemotherapy is used before surgery for bulky or locally advanced tumour is in order to make them smaller prior to surgery. If several months of chemotherapy is used as well as radiotherapy treatment, this is an approach called TNT (total neoadjuvant therapy) which is now increasingly used to manage bulky tumours. This leads to better downsizing of the tumour, thus facilitating an easier operation to remove the tumour completely. Chemotherapy is also much better tolerated before surgery than after surgery.

This is a type of “internal” radiotherapy, where a probe is inserted into the rectum and high-dose radiation is released into the tumour. It is not used very often, but may be useful in patients as a booster dose of radiotherapy if they are not fit for an operation, it can be used for recurrent rectal tumours, and sometimes for early rectal cancers to avoid an operation.

Immunotherapy is used for rectal cancer only very rarely. It is used in a subtype adenocarcinoma which is called “MMR deficient” adenocarcinoma, and this represents 5% or less of rectal cancers. For this small group, immunotherapy works incredibly well and in most cases the tumour can shrink away completely, often with no surgery required. There is more information about immunotherapy on the Bowel Cancer treatment page.

TNT is an advanced treatment approach primarily used for locally advanced rectal cancer. It involves delivering all the necessary chemotherapy and radiation therapy before surgery, rather than splitting treatments between pre- and post-surgery phases. If patients are not suitable for operation, RT dosage can be boosted to increase the chance of complete response to treatment, evidenced on CT/MRI/Endoscopy. Up to 50% of the time the tumour disappears and the surgical/oncology team will decide on whether to proceed with surgery. Scans and endoscopy cannot pick up very small traces of disease, especially in lymph nodes, so standard of care (SoC) is still offering surgery.

Patients with locally advanced tumours, where the surgical team is concerned about resecting the tumour with clear margins, may be offered primary radiotherapy before the operation. There is a lot of variation between clinicians about how and when to use RT:

• Down-sizing/Staging: Requires RT over 5-6 weeks alongside chemotherapy, typically given via tablets. Surgery post down-sizing/staging takes place 6-12 weeks later to allow time for response.
• Primary RT: Can reduce the risk of local recurrence in the future. short-course RT over 1 week without chemotherapy is used, with surgery usually a few weeks later.

Recurrence rates are low: between 2-3%. However, the closer the tumour is to the anus, the higher the recurrence rate (up to 5-10% for tumours very close to the anus).