Welcome @morris.
I moved your message to the Prostate Cancer thread so that you can connect with @BuckyFestoon @giddyup1 and others.

It appears that there is a lack of clinical evidence on whether marijuana (cannabis) can help treat prostate cancer. See this review that describes in detail the effects, characteristics, and possible role of cannabis and cannabinoids in the subject of prostate cancer. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3339795/

According to the National Cancer Institute, cannabis may have some effect treating cancer-related symptoms caused by cancer or its treatments http://www.cancer.gov/about-cancer/treatment/cam/hp/cannabis-pdq

You may also find this article interesting to read, titled "Don’t count on marijuana to treat prostate cancer" http://healthydebate.ca/personal-health-navigator/can-marijuana-cure-prostate-cancer

Morris, what treatments are you currently taking?

Not aware of any impact on PCa other than palliative but, like everything else, knowledge is evolving.