Importance of Adding ADT to Brachy Boost Therapy for Men with Unfavorable-Risk Prostate Cancer

Last month, we looked at Level 1 evidence (highest level, superseding all previous studies) that for unfavorable risk patients, brachy boost therapy (BBT) [external beam therapy (EBRT) with a brachytherapy boost to the prostate] has better results when accompanied by 18 months of androgen deprivation therapy (ADT). (see this link)

Now a meta-analysis has reaffirmed that finding. The two studies were probably submitted for publication at about the same time, which explains why the meta-analysis doesn't include data from RTOG 01.03 RADAR. In the Jackson et al. meta-analysis (and Medpage summary), there were:

• 6 randomized trials of EBRT with or without ADT comprising 4,663 patients.
• 3 randomized trials of EBRT with or without a BBT comprising  718 patients.
• One of those trials included ADT, the other two did not

Their analysis found that ten-year overall survival was:

• improved by 30% by the addition of ADT to EBRT
• not improved by the addition of BBT to EBRT (at least when ADT was not included)
• The addition of ADT had a bigger impact than the addition of BBT
• The trial that included both ADT and BBT had the best results

Because this meta-analysis included trials with men from different risk levels, it gives no direction about which therapy is best for favorable- vs unfavorable-risk men. DART 01/03 GICOR proved that adjuvant ADT only provides an added benefit to EBRT in high-risk men (vs intermediate risk men). Furthermore, BBT did not benefit and did add toxicity to favorable-risk patients (see this link).

Some of the trials did not include radiation doses now considered curative. It also did not look at ADT duration.