ESTRO 2020 Abstract book

S379 ESTRO 2020

localized intermediate- and high-risk prostate cancer. To date, no differences were seen in CSS and OS. When toxicity at 5-year follow-up remains comparable between both arms (no difference was observed after 2 years), addition of a focal boost should be considered standard treatment for intermediate- and high-risk prostate cancer. OC-0613 Prostate Only or Pelvic Radiotherapy in High Risk Prostate Cancer: Outcomes of a Randomised Trial V. Murthy 1 , P. Maitre 1 , G. Panigrahi 1 , D. Chaurasia 1 , R. Krishnatry 1 , R. Phurailatpam 2 , G. Prakash 3 , G. Bakshi 3 , M. Pal 3 , S. Menon 4 , U. Mahantshetty 1 1 advanced Centre For Treatment- Research And Education In Cancer- Mumbai, Radiation Oncology, Mumbai, India ; 2 advanced Centre For Treatment- Research And Education In Cancer- Mumbai, Medical Physics, Mumbai, India ; 3 advanced Centre For Treatment- Research And Education In Cancer- Mumbai, Urological Oncology, Mumbai, India ; 4 advanced Centre For Treatment- Research And Education In Cancer- Mumbai, Pathology, Mumbai, India Purpose or Objective To report long term clinical outcomes from a randomised trial of prostate only versus whole pelvic radiotherapy in high risk, node negative prostate cancer. Material and Methods Patients with node negative, locally advanced prostate adenocarcinoma and Roach nodal risk >20%, were randomised to prostate only (PORT, 68Gy/25# to prostate) or whole pelvis (WPRT, 68Gy/25# to prostate and 50Gy/25# to pelvic nodes as simultaneous integrated boost) arms, with stratification for TURP, Gleason score (GS), baseline PSA, and type of androgen deprivation therapy (ADT). All patients received daily image guided intensity modulated radiotherapy and two years of ADT. Ga[68] PSMA PET-CT was used for disease staging at baseline and recurrence. Primary endpoint was 5-year biochemical failure-free survival (BFFS), defined from the date of randomisation using the Phoenix definition. Survival outcomes were estimated using Kaplan Meier method and compared between the two arms using log rank test. Results Total 224 patients were randomised (PORT 114, WPRT 110) from November 2011 to August 2017. Median baseline serum PSA was 28 ng/mL (IQR 13.66-52.89) and the median nodal risk was 42% (IQR 24.6-52.8). GS was 8-10 in 49% of patients and 25% had GS 9-10. Clinical stage T3-4 was seen in 78% patients. At a median follow up of 51 months, 5- year BFFS was 95.3% with WPRT versus 79.3% with PORT (p<0.0001) (Figure 1). There were a total of 30 biochemical failure (BCF) events (WPRT=5, PORT=25), with median time to BCF being 45.5 months (IQR 25.5-61) . The PSMA PET detected sites of recurrences are shown in Table 1. There were 7 (28%) and 0 isolated pelvic nodal recurrences in the PORT and WPRT arms respectively. There was no difference between the WPRT and PORT arms for 5-year overall survival (91.4% vs 89.6%, p=0.632) or prostate cancer specific survival (96.9% vs 94.7%, p=0.645). Acute bladder and bowel toxicities and late bowel toxicity were similar for both arms, whereas late ≥grade II bladder toxicity was higher with WPRT (17.7% vs 7.5%, p=0.03).

Regional only

Distant Only

Regional and distant

PSA only

Trial Arm

WPRT (n=5) PORT (n=25)

0 1 2

2

7 6 8

4

Conclusion Addition of pelvic irradiation for localised prostate cancer with a high risk of nodal involvement resulted in significantly improved biochemical failure-free survival as compared to prostate only RT, but showed no impact on overall or prostate cancer specific survival. The late RTOG grade 2 urinary toxicity was higher with WPRT.