STAMPEDE suggests radiation OS benefit for select metastatic prostate cancer patients
medwireNews: The latest results from the STAMPEDE trial do not show an additional overall survival (OS) benefit with radiotherapy for men undergoing androgen deprivation therapy (ADT) with or without docetaxel for newly diagnosed metastatic prostate cancer.
However, the findings reported at the ESMO 2018 Congress in Munich, Germany, did indicate that the 40% of participants with a low metastatic burden, defined as per the CHAARTED trial, derived a significant extension of OS with radiotherapy, delivered as either 35 Gy over six weekly fractions or 55 Gy given in 20 fractions over 4 weeks.
The men in this subgroup who were randomly assigned to receive radiation had a significant hazard ratio (HR) for death of 0.68 for 3-year OS (81 vs 73%) compared with those given only ADT with or without chemotherapy. By contrast, there was no significant OS benefit detected for the use of radiation among the full study population of 2061 men or the 54% of men who had a high disease burden.
As the OS results in the men with a low metastatic burden fulfill key markers of subgroup analysis credibility, such as consistency of results among earlier studies and related outcomes, “we can be confident that this is a robust, reliable finding on which we can base clinical practice,” said presenting author Christopher Parker (The Royal Marsden Hospital, London, UK).
He reported a significant improvement in failure-free survival at 3 years with radiotherapy in the full study group (32 vs 23%, HR=0.76), as well as a “marked benefit” among men with a low metastatic burden (50 vs 33%, HR=0.59). But no radiation effect was found for those with a high metastatic burden (18 vs 17%).
Discussing the toxicity results, Parker said that the use of radiation was “well tolerated,” with one or more grade 3 treatment events reported by a comparable 38% of the radiotherapy arm and 39% of controls.
“Prostate radiotherapy should now be a standard treatment option for men with newly diagnosed metastatic prostate cancer with a low metastatic burden,” Parker therefore concluded.
“Furthermore, if prostate radiotherapy improves OS in men with distant metastases, then we can be reasonably confident that it would also improve OS in men with regional nodal metastases,” he said.
“So, right now men with pelvic nodal disease are often managed by ADT alone but I think this trial, even though it didn’t include this population of men with node-positive disease, means that prostate radiotherapy should now be standard for these men as well and ADT alone is no longer adequate.”
And the STAMPEDE investigator added that “having proved the principle in prostate cancer, that treatment of the primary tumor in patients with metastatic disease can improve OS, the same hypothesis should be tested in patients with metastatic disease from other malignancies.”
These results were simultaneously published in The Lancet.
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