medwireNews: Long-term postoperative androgen deprivation therapy (ADT) may improve metastasis-free survival (MFS) versus short-term therapy in men receiving radiotherapy after radical prostatectomy for prostate cancer, research suggests.
By contrast, there was no benefit with short-term ADT plus radiotherapy relative to radiotherapy alone.
The findings of the RADICALS-HD study were presented by Chris Parker, from The Royal Marsden Hospital – NHS Foundation Trust in Sutton, UK, at the ESMO Congress 2022 in Paris, France.
He told delegates that the median 10-year MFS rate was 78% in the 762 men with prostate cancer (71% Gleason score ≤7) who were randomly assigned to receive 24 months of ADT in combination with adjuvant (43%) or early salvage (57%) radiotherapy between 2007 and 2015.
By comparison, the 10-year MFS rate was a significantly lower 72% among the 761 men (72% Gleason score ≤7) who instead received ADT for 6 months alongside radiotherapy (43% adjuvant, 57% early salvage), with the difference corresponding to a significant 23% lower risk for metastases or death in favor of long-term ADT.
In addition, significantly more men in the long-term ADT group were free from salvage hormone therapy at 10 years in the long-term versus short-term ADT groups (75 vs 69%) but there was no significant difference between the two arms in 10-year overall survival (OS) rates, at 85% and 82%, respectively.
When short-duration ADT (n=743; 89% Gleason score ≤7) plus radiotherapy was compared with radiotherapy alone (n=737; 89% Gleason score ≤7), there was no significant difference in 10-year MFS between the two arms (80 vs 79%). In this comparison, radiotherapy timing was adjuvant for 29% of men who received short-term ADT and 28% of those who received radiotherapy alone, and early salvage for the remainder.
There was no significant difference between the short-term ADT and no ADT arms in the 10-year OS rate (85 vs 86%) but Parker noted that significantly more men had avoided salvage hormone therapy at 10 years in short-term ADT versus no ADT groups (82 vs 73%).
In all analyses, the effect size was consistent across all prespecified subgroups.
Session discussant Silke Gillessen, from the Oncology Institute of Southern Switzerland in Bellinzona, said that the study “addresses important open questions” about the optimal timing of ADT when combined with postoperative radiotherapy.
She pointed out that the patients included in the none versus short-term ADT comparison had less aggressive disease than those in the short-term versus long-term ADT comparison and suggested that the analyses should be considered as two different studies.
She said it seems clear that “some patients” will benefit from either short-term ADT versus no ADT or from long-term ADT versus short-term ADT but it is also important to remember than in these patient populations, most do well with radiotherapy alone. “So, the real question is how to better personalize therapy.”
Until predictive genomic or biomarker tests “are further validated and widely available we have to consider a combination of clinical factors […] to decide on addition of ADT,” Gillessen remarked.
She concluded: “Our goal needs to be optimal treatment intensification, but only for the patients who really need it.”
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ESMO Congress 2022; Paris, France: 9–13 September