Here's a great video about fighting prostate cancer growth: https://www.nutriliving.com/blog/key-slowing-prostate-cancer-growth
There are certain foods that have been shown beneficial for prostate health. These include lycopene-rich foods like tomatoes and watermelon.
Follow an anti-inflammatory diet (https://www.nutriliving.com/blog/top-10-anti-inflammatory-foods)
Some research shows a link between dairy and increased risk of prostate cancer: http://www.ncbi.nlm.nih.gov/pubmed/11566656