Every year in the UK, around 16,000 people are diagnosed with rectal cancer.
The main treatment is surgery, but this can be a major operation with possible risks during and after the procedure.

For people with locally advanced rectal cancer, treatment often begins with radiotherapy, sometimes combined with chemotherapy, to shrink the tumour before surgery.

There are two main types of pre‑surgery radiotherapy:

• Long‑course chemoradiotherapy (LCCRT):
  Given over several weeks, followed by major surgery about 8–15 weeks later.

• Short‑course radiotherapy (SCRT):
  A shorter, more intense course. Traditionally, surgery followed within 10 days, but newer studies show it can be safely delayed for 6–8 weeks.

For 10–20% of patients, chemoradiotherapy can make the tumour disappear completely on scans and endoscopy.
This is called a clinical complete response (cCR).

In these cases, instead of going straight to major surgery, doctors may offer a “watch‑and‑wait” (W&W) approach. This means close monitoring with regular checks, avoiding or delaying surgery unless the cancer returns.

This approach is becoming more common, but there are still questions about how safe it is in everyday practice outside of specialist centres.

Although a randomised trial would be the ideal way to compare surgery versus watch‑and‑wait for people with a complete response, experts believe such trials are unlikely to happen. Many patients strongly prefer to avoid major surgery if possible.

Because of this, researchers need to collect information in a standardised, long‑term way to understand:

• How patients with a complete response do over time
• How safe the watch‑and‑wait approach is in real‑world settings
• Which patients benefit most from avoiding surgery

In simple terms:
This study aims to carefully track patients whose tumours disappear after chemoradiotherapy, to better understand whether avoiding immediate major surgery is safe and effective for them.