The combination of radiotherapy and androgen deprivation therapy (ADT) is more effective than radiotherapy alone for preventing disease recurrence in men with localised prostate cancer, according to research findings presented at the European Society for Radiotherapy and Oncology (ESTRO) 33rd annual congress in Vienna, Austria.
Michael Bolla (Grenoble University Hospital, France), the study’s lead author, said that the findings needed to be taken into account in daily clinical practice. He said in a statement: “[D]uring multidisciplinary team meetings to discuss a patient’s treatment, this combined treatment approach should be one of the options proposed for men with localised prostate cancer that has an intermediate or high risk of growing and spreading.”
The “EORTC 22991” trial was conducted in 14 countries and involved 819 men with intermediate- or high-risk localised prostate cancer. They were randomly assigned to receive three-dimensional conformal radiotherapy with or without ADT.
Radiotherapy was delivered at one of three doses (70, 74 or 78 Grays) and could be intensity-modulated or not, according to the treating physicians’ preference. ADT comprised two injections, given three months apart, of a luteinising hormone–releasing hormone analogue that lasted for a total of 6 months. This was preceded by 15 days of treatment with the oral anti-androgen bicalutamide to prevent flare.
After a median follow-up of 7.2 years, radiotherapy plus hormone therapy was significantly better than radiotherapy alone for the endpoints of biochemical progression-free survival and clinical progression-free survival (PFS), with hazard ratios of 0.53 and 0.63, respectively.
Five-year rates of biochemical PFS were 92.5 percent in the combination therapy group versus 69.3 percent in those receiving radiotherapy alone, while rates of clinical PFS were 88.7 percent and 80.8 percent, respectively.
In terms of toxicity, severe impairment of sexual function was significantly more frequent with combination therapy than radiotherapy alone, at 27.0% versus 19.4%, whereas late genitourinary toxicity did not differ significantly between the groups, at 5.9 percent and 3.6 percent, respectively.
“Although we need longer follow-up to assess the impact on these men’s overall survival, these findings need to be taken into account in daily clinical practice,” Professor Bolla remarked.
Professor Vincenzo Valentini, president of ESTRO and a radiation oncologist, said, “The results from this trial are important and practice-changing. It is clear that an additional six months of hormonal treatment in addition to radiotherapy improves the outcome for men with localised prostate cancer. This option should now be considered for all these men with prostate cancer that is at risk of growing and spreading.”
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