3. Smoking and abusing alcohol increases your risk
Smoking is a source of many carcinogens and inflammatory substances. Carcinogens influence the DNA and cause mutations that lead to abnormal growth and immortal features in cancer cells. Inflammatory substances contribute to growth by increasing the blood flow to the cancer tissue. Cancer feeds off inflammation because it is fundamental to create new blood vessels and keep feeding the tumor as it grows.
On the other side, studies show that people who drink alcohol very heavily are more likely to grow colon cancer. This is true in men and women, but men are apparently at a slightly higher risk. The relationship is not entirely understood, but most studies suggest that alcohol damages the gastrointestinal tract, changes our hormone levels, and reduces folate absorption (low folate levels may also increase the risk of colon cancer).