Hoffman KE, et al. - In this randomized trial, researchers investigated whether dose-escalated, moderately hypofractionated intensity-modulated radiation therapy (HIMRT) vs conventionally fractionated IMRT (CIMRT) improves prostate cancer control for men with localized prostate cancer. Findings demonstrated that dose-escalated moderately hypofractionation radiotherapy yielded superior cancer control, while shortening treatment duration in these patients.

Methods

• Researchers performed random assignment of men to 75.6 Gy in 1.8-Gy fractions delivered over 8.4 weeks (CIMRT) or 72 Gy in 2.4 Gy fractions delivered over 6 weeks (HIMRT, biologically equivalent to 85 Gy in 1.8-Gy fractions assuming prostate cancer α-to-β ratio of 1.5).
• The definition of failure was prostate-specific antigen (PSA) failure (nadir plus 2 ng/mL) or initiation of salvage therapy.
• Grading of late (≥ 90 days after completion of radiotherapy) GI and genitourinary toxicity was done using Modified Radiation Therapy Oncology Group criteria.

Results

• cT1, Gleason score 6 or 7 (99%), and PSA level ≤ 10 ng/mL (90%) disease were present in most of the 206 men (72%).
• Data showed that, 24% were treated with androgen deprivation therapy.
• A median follow-up of 8.5 years revealed fewer treatment failures (n=10) among men treated with HIMRT vs men treated with CIMRT (n=21; P=.036).
• The estimated 8-year failure rate was 10.7% (95% CI, 5.8% to 19.1%) and 15.4% (95% CI, 9.1% to 25.4%) with HIMRT and with CIMRT, respectively.
• No difference in overall survival (P=.39) was seen.
• With HIMRT, a nonsignificant increase in late grade 2 or 3 GI toxicity was reported (8-year 5.0% v 12.6%; P=.08).
• However, data showed that, GI toxicity was only 8.6% when rectal volume receiving 65 Gy of HIMRT was ≤ 15%.
• Comparable (P=.84) late genitourinary toxicity was reported and no grade 4 toxicity was evident.