A recent study shows evidence that prostate tumor growth stops due to the ingestion of flaxseed.  The study took place over a 30 day period with several control goops and came to this conclusion: 

Flaxseed is thought to play a part in halting the cellular activity that leads to cancer growth and spread. One reason could be that as a source of omega-3 fatty acids, flaxseed can alter how cancer cells lump together or cling to other body cells, both factors in how fast cancer cells proliferate, Demark-Wahnefried said. The researchers also suspect that lignans may have antiangiogenic properties, meaning they are able to choke off a tumor's blood supply, stunting its growth.

The protective qualities of omega - 3's (such as flaxseed and fish oil) go beyond fighting cancer.  They are our body's lubricant; the oil that allows your body to function smoothly, to move with ease, exchange energy and keep your metabolism elevated.  You can not function optimally without it.