You raise an interesting concern. I think cancer risk truly varies from person to person, and genetics might play some part.
However, I think the paradigm on cancer and disease is changing rapidly to acknowledge the role of environmental stressors.
Some new data would suggest that epigenetics plays more of a role than previously thought. Environmental factors like lifestyle, diet, stress do indeed affect the risk, though the percentage is unknown.
It is entirely within the realm of possibility for one to reduce their risk. Nothing is ever set in stone. We know for instance that legumes and resistant starches reduce colon cancer risk. Things like chronic stress (and inflammation) can also turn genes on and off.
It is also possible for one to build up their microbiome to mitigate the risk, since both colon cancer and IBD are linked to poor bacterial diversity.
I invite you to look into the new studies on resistant starches - things like prebiotics, probiotics all play some part in healing the colon. Stress reduction and proper sleep are perhaps the most important.
Best.
Post Edited (Guardian7) : 1/30/2015 7:56:21 AM (GMT-7)