CHHiP

Clinical question: Can 60 Gy in 20 fractions replace conventional 74 Gy in 37 fractions for localized prostate cancer?

Design: Phase III randomized non-inferiority trial; 3,216 men with T1b–T3aN0M0 localized prostate cancer. Three arms: 74/37, 60/20, 57/19 Gy, all with IMRT. Most patients received 3–6 months ADT. Median follow-up 62.4 months.

Primary result

5-year biochemical/clinical failure-free survival: 74/37: 88.3%; 60/20: 90.6%; 57/19: 85.9%. The 60/20 regimen met the prespecified non-inferiority criterion; 57/19 did not.

Observed absolute difference for 60/20 was +2.3 percentage points, but because this was a non-inferiority design, this is not an established superiority benefit; no NNT is assigned.

Toxicity

At 5 years, grade ≥2 bowel toxicity was 11.9% with 60/20 versus 13.7% with 74/37; grade ≥2 bladder toxicity was 11.7% versus 9.1%. Patient-reported bowel and urinary symptoms were broadly similar, with some time-dependent differences.

Methodology

Three-arm randomized non-inferiority design. The critical HR threshold for the 60/20 comparison was approximately 1.208. Importantly, the widespread use of short-course ADT means CHHiP tests the hypofractionated RT schedule within a treatment package that included hormonal therapy for most participants.

Our take

CHHiP provides strong evidence that 60 Gy in 20 fractions can replace 74 Gy in 37 fractions for appropriately selected localized prostate cancer, with a major reduction in treatment duration from about 7.4 weeks to 4 weeks. The trial should not be interpreted as evidence that 60/20 is intrinsically superior; its main value is equivalent cancer control with substantially greater convenience.

Primary source

Dearnaley et al., Lancet Oncology 2016