Thanks for your query.Based on the facts that you have posted it appears that you have some myths in your mind .Frequent masturbation
does not prevent cancer of the prostate
It is very difficult to comment about frequency of masturbation.
The advantage of masturbation is you get satisfaction of sexual enjoyment even without a partner..
There are no proved disadvantages of masturbation but if practised too frequently may harm quantity and quality of sperms needed for conception.