Zoladex improves the success of any treatment. Chemo is traditionally used for cancer. I don't know for how long it is effective but combining the two gives good results.
Because of the effect of chemo on the immune system during the pandemic chemo was not used so much, but arbiterone which is much more expensive was used instead. As COVID prevalence is higher now than ever before chemo is still too risky.
I have no references to studies to show how effective each treatment is. I hope the above at least sheds some light on why this is being recommended.