Hi R:  Your question is one that has been debated quite a bit lately.  There are Dr.s who feel that testosterone therapy can increase the *chance* of acquiring prostate cancer, but this theory has been shifting and I think you should talk to your Dr about it and if possible get a second opinion from either an oncologist or Dr that specializes in the prostate.

Raising your testosterone, along with taking supplements and one of the bone meds should help to increase your bone density, but since you have an enlarged prostate, you want to make sure that the therapy that will help your bones won't hinder your prostate.

Here are two links on this topic, that may help to explain from MedPage Today and NewsMax.  If you want to read more about this topic, look for clinical studies done by major educational institutions (New England Journal of Med, Mayo Clinic, Cleveland Clinic, National Institute of Health, Harvard etc) with *current* studies on this issue. 

Good luck with your decision and I hope you find a resonable solution.