I think you should be fine. The rules posted by Bluebird are pretty good guidelines. I think if you have actually gone through prostate cancer, found a product that helped you, you aren't making money off of the sale of the product, etc. It is fine.
Some " hypothetical examples" of types of posts that usually are against forum rules: (I am just making these examples up, but sometimes you see posts like this),
Someone with no posts on prostate forum posts "hey, i just found this great product, it is a ginseng/black tea pill with some secret additional ingredient that works to cure cancer! Come visit this website and see the testmonials!! I know dozens of people CURED of all cancer with this miracle pill!!"
Then two minutes later, they are posting the exact same thing on say the Parkinson's forum. Cure your parkinsons!!
blah, blah, blah. That is the type of spam that is frowned upon. Posting something you have found helpful to YOU that you aren't actually selling is fine :) As long as you aren't pushing it, etc. Just something you found helpful and the source of info/sales of it, should be fine.
That's how i interepet the rules anyway.