Inoperable Prostate Cancer

My husband is 56 and has been dx with pc right after I finished treatments for bc. He had a psa of 49 and gleason score of 8 or 9. We were told it had already spread outside the capsule so an operation was not an option. He had a month of radiation but his psa gradually started to climb back up. He is getting zoledex shots every three months except for this past visit last week, he decided to try 3 more months making it 6 months between shots instead of the three. Does anyone think there is harm in going six months instead of three? Anyone out there have the same problem but being treated differently? Thank You!