Cancer is a renegade system of growth inside the human body. The changes that must occur inside for cancer to flourish are genetic changes, but factors outside the body also play a role.

Humans do not exist in contaminant-free surroundings. Over a lifetime, a person's internal genetic makeup persistently interacts with external factors. Factors outside the body such as diet, smoking, alcohol use, hormone levels, or exposures to certain viruses and cancer-linked chemicals (carcinogens) over time may collectively conspire with internal genetic mutations to destabilize normal checks and balances on growth and maturation. (Please see Understanding Cancer ¹ for more information.)