Thanks Andy for the clarification. There was a reason I was careful to say "at the level of the cancer", but while I was well aware of the importance of the hypothalamic-pituitary axis I have to admit my knowledge of endocrine physiology starts falling apart when you get to the details.
So-called phyto-oestrogens (they are flavonoids which have a general molecular resemblance to oestrogens, but have evolved to carry out completely different functions in plants) bind the oestrogen receptors in humans much less strongly than their real counterpart. I suspect the amounts of phyto-oestrogen you would have to take to have the effect of diethylstilbestrol is so high there is a risk of side effects.
Despite Lizzo's reservations the probability of eliminating a cancer is best when the cancer is smallest - in other words when it is known to be present from the PSA reading but is still too small to be detected by scans. The longer you delay radiotherapy the greater the risk of it not completely eliminating the cancer.
I hope Lizzo's husband is fully aware of the risk he is taking by not following his doctor's advice, which will have been given on the basis of his personal situation.