Hypofractionation noninferior to conventional fractionation for localized PCa

March 2, 2020

Modest hypofractionation is noninferior to conventional fractionation in the treatment of localized prostate cancer and causes no increase in side effects, according to 8-year outcomes from the CHHiP trial.

Modest hypofractionation is noninferior to conventional fractionation in the treatment of localized prostate cancer and causes no increase in side effects, according to 8-year outcomes from the Conventional or hypo-fractionated high-dose intensity-modulated radiotherapy for prostate cancer, or CHHiP trial.

“CHHiP is the largest treatment trial undertaken in localized prostate cancer, recruiting over 3,200 patients internationally,” said lead author David P. Dearnaley, MD, who presented the data at the GU Cancers Symposium in San Francisco.

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The 8-year follow-up, with more than 700 patients followed for 10 years or more, offers urologists and other providers increased confidence that the shorter radiotherapy schedule given as 20 treatments over 4 weeks is just as effective and safe as the previous, more conventional 7.5-week treatment, according to Dr. Dearnaley, of The Institute of Cancer Research and Royal Marsden NHS Foundation Trust, in London.

In essence, shorter course modestly hypofractionated radiotherapy is effective, safe, convenient, and resource saving, he said.

The phase III randomized controlled trial tested moderate hypofractionation against standard fractionation using two-gray (Gy) fractions in localized prostate cancer. Patients were randomized 1:1:1, with the standard, or control, group receiving 74 Gy/37 fractions (f). The two experimental groups received 60 Gy/20f or 57 Gy/19f.

The follow-up data confirm the 60-Gy schedule is noninferior to the 74-Gy schedule, specifically showing that 8-year event-free rates were 80.6% among controls, 83.7% in the 60-Gy group, and 78.5% in the 57-Gy group.

When the authors looked at patients older than 75 years of age, the slightly lower dose of 57-Gy in 19 fractions provided highly satisfactory results. The finding in older patients confirms findings previously reported after 5 years of follow-up, according to Dr. Dearnaley.

To clinicians, that means that they can safely give the lower schedule to older patients knowing that it’s going to be effective and appears to be associated with a lower level of side effects, he said.

Next:95% metastases-free rate at 8 yearsOverall, the metastases-free rate at 8 years was 95%, which was similar in all randomized groups. Survival of 86% to 89% at 8 years reflects death from causes other than prostate cancer. And clinician-reported bowel and bladder side effects were 2% or less in all groups at 5 years, according to Dr. Dearnaley.

“Using state-of-the-art intensity modulated radiotherapy and auditing radiotherapy treatments to meet specified dose constraints maintains patient safety,” he said.

“We conducted a non-inferiority study as it wasn’t necessary to show hypofractionation was more effective but rather that it was just as effective with no increase in side effects,” according to Dr. Dearnaley.

But in fact, the results suggest the 4-week schedule is marginally more effective than conventional fractionation for localized prostate cancer, he said.

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Hypofractionated radiotherapy is standard of care and mandated in the United Kingdom for treatment of localized prostate cancer. It is recommended as an option in the rest of Europe and in North American guidelines, Dr. Dearnaley said.

These findings should change practice for those still using conventional 2-Gy schedules over 7.5 weeks in localized prostate cancer, he said.

“Longer term follow-up is always welcome and is in progress. Translational research is ongoing,” he said.

Dr. Dearnaley has consulting or other relationships with Janssen, Sandoz, Takeda, Cadence Research and Consulting, FirstWord, Janssen Research & Development, and Cilag.