Prostate cancer is very common, with around 50,000 men diagnosed every year in the UK. Even after treatments given with the aim of curing the cancer, such as surgery or radiotherapy, the cancer can come back in up to half of men with higher‑risk disease.

A common place for the cancer to return is the pelvic lymph nodes—small glands in the pelvis that help the body fight infection. When cancer comes back in these nodes, it can lead to worse long-term outcomes if not treated effectively.

Modern scanning, especially PET‑CT, can now pick up very small areas of recurrence in the pelvic lymph nodes when a patient’s PSA level rises after previous treatment.
However, there is currently no clear standard treatment for this type of recurrence.

Clinicians may offer:

• Stereotactic Body Radiotherapy (SBRT):
  Highly targeted treatment to the affected lymph node(s).

• Extended Nodal Irradiation (ENI):
  A wider radiotherapy field that treats both the known cancer and nearby lymph nodes where tiny cancer cells might also be present.

• Systemic treatments, such as:

  • androgen deprivation therapy (ADT)
  • chemotherapy (e.g., docetaxel)
  • newer hormone therapies

SBRT works well at controlling cancer in the area being treated and usually causes few side effects. But we do not yet know whether SBRT helps prevent the cancer from spreading further or whether repeated SBRT is effective if the cancer returns again.

Studies looking at ENI suggest it may improve the length of time before the cancer spreads elsewhere, while still causing low levels of severe long-term side effects. ENI can also be given in just 5 treatment sessions, which has been shown to be safe in other prostate cancer settings.

A randomised controlled trial is now needed to directly compare:

• SBRT to the affected lymph node(s)
  versus
• ENI, delivered in either:
  • 5 radiotherapy sessions, or
  • 20 radiotherapy sessions (the current standard)

The trial will look at:

• whether ENI better prevents cancer from spreading compared with SBRT
• whether the shorter 5‑session ENI schedule is as safe as the standard 20‑session schedule
• how each treatment affects side effects, quality of life, and long-term outcomes

This study will help clinicians understand the best way to treat men whose prostate cancer has returned in the pelvic lymph nodes, using modern radiotherapy approaches that aim to balance cancer control with quality of life.