Trelstar (triptorelin) can be given for prostate cancer as long as it is tolerated and your doctor believes it is still safe and effective for you, which may be many years. Trelstar is intended as a long-term treatment, and despite the inevitable progression to castration-resistant prostate cancer (CRPC) in most patients receiving androgen deprivation therapies (ADT), such as Trelstar, there may still be benefits in continuing ADT in men in addition to introducing other treatment options for CRPC.