Ultra-hypofractionated and Conventional-fractionated Boost Yield Similar Results in Men with High-risk Prostate Cancer

Presenting author:
Piotr Milecki II, PhD

By Nataniel H. Lester-Coll, MD, Assistant Professor of Radiation Oncology, University of Vermont Larner College of Medicine

Prostate boost delivered with ultra-hypofractionated radiation therapy (UF-RT) and conventional-fractioned radiation therapy (CF-RT) following whole pelvic CF-RT and androgen deprivation therapy yield similar five-year results in men with high-risk prostate cancer according a new randomized trial, presented in the abstract Ultra-Hypofractionated versus Conventionally Fractionated Radiation Therapy Boost for Patients with High-Risk, Localized Prostate Cancer: 5-Year Results from Randomized HYPO-PROST Trial.

All participants in this study received 28 months of androgen deprivation and received CF-RT to the prostate, seminal vesicles and pelvic lymph nodes to a dose of 46 Gy in 2 Gy fractions. Participants were then randomized to receive a prostate boost using either CF-RT (30 Gy in 15 fractions) or UF-RT (15 Gy in 2 fractions) using image-guided intensity modulated radiation therapy. The primary outcome was tolerance, based on genitourinary and gastrointestinal toxicities according the RTOG/EORTC criteria. Secondary outcomes including biochemical relapse free survival (BRFS), metastases-free survival (MFS) and overall survival (OS).

There were 208 participants included in this analysis with a median follow-up of 60 months. The trial found no significant differences in late grade 2 or higher gastrointestinal toxicity (13.9% vs. 8.6%, p=0.18), genitourinary toxicity (5.9% vs. 5.8%, p=0.91), BRFS (82.9% vs. 78.2%, p=0.33), MFS (90.5% vs. 87.1%, p=0.38) and OS (93.3% vs. 87.1%, p=0.12) between UF-RT and CF-RT prostate boost.

This trial contributes to growing literature supporting the use of UF-RT in prostate cancer. The HYPO-PROST Trial is an important contribution, as level one evidence supporting UF-RT is largely limited to men with low- and intermediate-risk disease, such as the HYPO-RT-PC Trial, which only included 11% of men with high-risk disease. The HYPO-PROST Trial importantly incorporates long-term androgen deprivation therapy for patients with high-risk disease. Longer follow-up will be needed in order to confirm no differences in late toxicity beyond five years, but these are very encouraging results. Ongoing prospective trials are also evaluating stereotactic techniques in high-risk prostate cancer.

Improvements in technology are now enabling radiation oncologists to safely deliver higher doses of RT using shorter schedules. Shorter radiation schedules of radiation therapy are convenient for patients and cost-effective.

Ultra-Hypofractionated versus Conventionally Fractionated Radiation Therapy Boost for Patients with High-Risk, Localized Prostate Cancer: 5-Year Results from Randomized HYPO-PROST Trial was released onDemand on Monday, October 26 in the Science Center, as part of Scientific Session SS 22.

Published on: October 27, 2020