In his recently published book on hormone treatment and diet, Dr Charles Myers has a section on myths, myth #1 being that hormone therapy is only effective for 18 months.
Apparently that theory started some years ago when research was presented relating to one section of men at that time who were generally diagnosed at a much later stage than is uaually the case today.
Dr Myers also makes the following points:
That figure related to very advanced cases; even then many had a lot better prognosis.
it was an average, and you do not have to be average,
treatment options have also improved,
most men he sees who have been classed as hormone resistant are not.