Eight-year outcomes of a phase III randomized trial of conventional versus hypofractionated high-dose intensity modulated radiotherapy for prostate cancer (CRUK/06/016): Update from the CHHiP Trial

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Background: CHHiP is a non-inferiority trial to determine efficacy and safety of hypofractionated radiotherapy for localised prostate cancer (PCa). Five year results indicated that moderate hypofractionation of 60 Gray (Gy)/20 fractions (f) was non-inferior to 74Gy/37f (Lancet Oncology, 2016). Moderate hypofractionation is now an international standard of care but with patients remaining at risk of recurrence for many years, information on long-term outcomes is important. Here we report pre-planned analysis of 8 year outcomes. Methods: Between October 2002 and June 2011, 3216 men with node negative T1b-T3a localised PCa with risk of seminal vesical involvement ≤30% were randomised (1:1:1 ratio) to 74Gy/37f (control), 60Gy/20f or 57Gy/19f. Androgen deprivation began at least 3 months prior to radiotherapy (RT) and continued until end of RT. The primary endpoint was time to biochemical failure (Phoenix consensus guidelines) or clinical failure (BCF). The non-inferiority design specified a critical hazard ratio (HR) of 1.208 for each hypofractionated schedule compared to 74Gy/37f. Late toxicity was assessed at 5 years by RTOG and LENT-SOM scales. Analysis was by intention-to-treat. Results: With a median follow up of 9.2 years, 8 year BCF-free rates (95% CI) were 74Gy: 80.6% (77.9%, 83.0%); 60Gy: 83.7% (81.2%, 85.9%) and 57Gy: 78.5% (75.8%, 81.0%). For 60Gy/20f, non-inferiority was confirmed: HR60=0.84 (90% CI 0.71, 0.99). For 57Gy/19f, non-inferiority could not be declared: HR57=1.17 (90% CI 1.00, 1.37). Clinician assessments of late toxicity were similar across groups. At 5 years, RTOG grade≥2 (G2+) bowel toxicity was observed in 14/879 (1.6%), 18/908 (2.0%) and 17/904 (1.9%) of the 74Gy, 60Gy and 57Gy groups respectively. RTOG G2+ bladder toxicity was observed in 17/879 (1.9%), 14/908 (1.5%) and 17/904 (1.9%) of the 74Gy, 60Gy and 57Gy groups respectively. Conclusions: With BCF rates over 80%, long-term follow-up confirms that 60Gy/20f is non-inferior to 74Gy/37f. Late side effects were very low across all groups. These results support the continued use of 60Gy/20f as standard of care for men with localised PCa. Clinical trial information: 97182923.

Efficacy and toxicity according to hormone therapy used in the CHHiP trial

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Background: CHHiP (CRUK/06/016) is a multicentre randomised controlled trial which investigated the use of moderately hypofractionated radiotherapy (RT) dose schedules for treatment of localised prostate cancer. 97% of participants (pts) had concurrent androgen deprivation therapy (ADT). Luteinising Hormone Releasing Hormone analogues (LHRHa) and bicalutamide 150mg (BIC) daily were permitted. This exploratory analysis investigates whether both ADT regimens show similar efficacy and whether BIC has the propensity to preserve erectile function. Methods: In CHHiP, 2700 pts received LHRH and 403 BIC, median duration 5.6 months. The primary endpoint was biochemical or clinical failure (BCF). ADT groups were compared with Cox regression adjusted forage, NCCN risk group, Gleason score,T-stage and stratified by RT dose. A key secondary endpoint was erectile function assessed by clinicians (LENTSOM subjective erectile function for vaginal penetration score) and pts (single items within UCLA-PCI and EPIC-50 questionnaires) at 2 years. 195/875 (22%) pts were excluded from this toxicity analysis as they had erectile dysfunction pre-ADT (grade (G) 3/4 LENTSOM). A chi square trend test compared ADT regimens. Results: Baseline demographics were similar except BIC pts were significantly younger (median 67 years BIC, 69 years LHRHa). With a median follow-up of 9.2 years, there was no evidence of a difference in BCF with an adjusted hazard ratio 0.95 (95% CI 0.75-1.20), p = 0.657. Eight year BCF rates were 80.7% (95%CI 79.0-82.2) and 80.3% (95%CI 75.8-84.0) for LHRHa and BIC pts respectively. At two years, LENTSOM erectile function was significantly worse (p < 0.0001) for LHRHa pts with 93/585 (16%), 95/585 (16%) and 125/585 (21%) G2, G3 and G4, compared to 3/68 (4%), 5/68 (7%) and 9/68 (13%) in BIC. At 2 years, the ability to have an erection, as reported by pts, was graded poor and very poor in 73/278 (26%) and 57/278 (21%) LHRHa pts and 5/23 (22%) and 4/23 (17%) in BIC pts (p = 0.584). Conclusions: There was no evidence of a difference in efficacy according to ADT received. BIC preserved clinician assessed (LENTSOM) erectile function at 2 years but patient reported outcomes did not show statistically significant differences with type of ADT. Clinical trial information: 97182923.