ESTRO 2023

Session Item

Monday

May 15

16:30 - 17:30

Hall A

Prostate SBRT

Co-Chair: Federica Ferrario, Italy;

Chair: Gilles Crehange, France

Session Code: 3470

Session Type: Proffered Papers

Track: Clinical

17:00 - 17:10

Prostate RT In high risk or N+ Moderate vs Extreme hypofractionation (PRIME): An Interim analysis

Vedang Murthy, India

Presentation Number: OC-0924

Abstract

Abstract Title:

Prostate RT In high risk or N+ Moderate vs Extreme hypofractionation (PRIME): An Interim analysis

Authors:

Vedang Murthy¹, Priyamvada Maitre¹, Moses Arunsingh², Reena Phurailatpam³, Ritesh Mhatre³, Balakrishnan Arun⁴, Gitanjali Panigrahi¹, Pallavi Singh¹, Santosh Menon⁵, Gagan Prakash⁶, Mahendra Pal⁶, Amandeep Arora⁶, Aparna Katdare⁷, Archi Agrawal⁸, Venkatesh Rangarajan⁸, Sadhana Kannan⁹, Indranil Mallick²

¹Tata Memorial Centre, Homi Bhabha National Institute, Radiation Oncology, Mumbai, India; ²Tata Medical Center, Radiation Oncology, Kolkata, India; ³Tata Memorial Centre, Homi Bhabha National Institute, Medical Physics, Mumbai, India; ⁴Tata Medical Center, Medical Physics, Kolkata, India; ⁵Tata Memorial Centre, Homi Bhabha National Institute, Pathology, Mumbai, India; ⁶Tata Memorial Centre, Homi Bhabha National Institute, Surgery, Mumbai, India; ⁷Tata Memorial Centre, Homi Bhabha National Institute, Radiodiagnosis, Mumbai, India; ⁸Tata Memorial Centre, Homi Bhabha National Institute, Nuclear Medicine and Molecular Imaging, Mumbai, India; ⁹Tata Memorial Centre, Homi Bhabha National Institute, Clinical Research Secretariat, Mumbai, India

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Purpose or Objective

Safety of SBRT for high-risk and node-positive prostate cancer is not yet established. We report 90-day toxicity and QOL from the pre-planned interim analysis of the ongoing phase III, multicentric, randomised PRIME trial (NCT03561961).

Material and Methods

Patients with NCCN high-risk or node-positive prostate adenocarcinoma (non-regional nodes or distant metastases excluded) are being randomised 1:1 to moderate (MHRT) or extreme (SBRT) hypofractionated RT. Patients in the MHRT arm received 68Gy/25# or 62Gy/20# to prostate, 50Gy/25# or 44Gy/20# to the pelvis, and in the SBRT arm 36.25Gy/5# with 25Gy/5# to the pelvis. ADT was prescribed for at least 24 months without systemic intensification. Toxicity using CTCAE v5.0, and QOL using EORTC QLQC-30 and PR-25 was recorded at baseline, RT completion, at 3-6 weeks, and then 3-6 monthly, with a threshold of 10 points change in the mean QOL scores for minimal clinically important change (MCIC). While the trial targets a sample of 464 for primary endpoint of 5-year biochemical failure-free survival, we report the cumulative 90-day toxicity and QOL for patients randomised till a pre-planned interim analysis.

Results

Total 307 randomised patients (N0=241, N1=66) were analysed, MHRT=153 and SBRT=154. Of these, 296 received RT and were eligible for toxicity reporting. Table 1 shows the cumulative 90-day urinary (GU) and gastrointestinal (GI) toxicities. Grade 3 GU toxicity was low, and observed in 3 patients (SBRT=1, MHRT=2), GI in 2 patients (1 each in MHRT and SBRT), without any grade 4 toxicity. Grade 2 acute GU and GI toxicities were similar for MHRT and SBRT (GU 33.1% vs 31.8%, p=0.5; GI 17.2 vs 15.2, p=0.9). Change in the mean QOL scores before and after RT for urinary symptoms was 9.4 for MHRT (26.6 to 36.0) and 5.1 for SBRT (27.5 to 32.6). For GI symptoms, the change in mean QOL was 1.9 for MHRT (7.4 to 9.3) and 0 for SBRT (6.7 to 6.7). Both of these were below the pre-defined threshold of MCIC.

Table 1: Cumulative 90-day urinary and gastrointestinal toxicities [*CTCAE grade 3 toxicity in parentheses, others grade 2]

Conclusion

Interim analysis from the ongoing multicentric randomised trial PRIME showed low rate of grade 3 acute toxicities for MHRT and SBRT, with similar toxicities and QOL for these two hypofractionated schedules of radiotherapy in high risk and node positive prostate cancer.