**5.1 Role of RT in high risk prostate cancer**

#### **Indications for RT after RP**

As stated earlier, currently, a multimodal treatment is chosen to increase survival and reduce biochemical progression. In this sense the RT play an important role.

There are two important studies about this:

The EORTC Trial 22911 included 1,005 patients with positive surgical margins or pT3 disease (extracapsular extension and seminal vesicle involvement) and randomized them to adjuvant EBRT (50 Gy to the prostatic fossa and periprostatic tissue plus a 10–14 Gy boost to the prostatic fossa only) versus no immediate treatment. (55) The cumulative rate of loco regional failure was significantly lower in the irradiated group (*P* <0.0001). However, other clinically important endpoints were not improved. In particular, 5-year metastasis-free survival, cause-specific survival, and overall survival were not affected by adjuvant RT.

The Southwest Oncology Group (SWOG) trial 8794 included 425 patients with high-risk localized disease, who were randomized to receive either 60–64 Gy to the prostatic fossa or observation only. (56) Biochemical control, disease-free survival, cancer-specific mortality, and overall survival were significantly increased in the adjuvant irradiation arm at a median follow-up of 10.6 years.

Both the EORTC and SWOG randomized trials, provide evidence that adjuvant postprostatectomy irradiation reduces the risk of biochemical recurrence and local clinical failure. It remains uncertain, whether administration of radiation immediately after PSA is detected, could provide equally effective long-term outcomes to patients receiving

adjuvant therapy, while sparing such patients from unnecessary irradiation. (17) (48)

#### **Salvage radiotherapy**

The efficacy of radiotherapy in the setting of a rising PSA after RP is unproven, and its use is highly controversial. Stephenson et al. reported on a large retrospective analysis of salvage irradiation of 501 patients from 5 institutions. (57)

Positive surgical margins, Gleason scores <8, or PSADT >10 months. In such patients, PSA relapse-free survival outcomes were in the range of 70% to 80% at 3 years.
