BusyBodyHealth

Some unsuspected sources are:

Laundry Detergents

Microwave/Plastic Containers

Stress

Chronic Inflammation - sugar & grains

Pesticides (in foods)

Chemical from aerosol cans

Grante counter tops (emits radon)

Hair Dyes

Mammograms

Canola Oil (omega-6)

Aspartame

Soy and soy based products - unless it's fermented such as natto. 91% of soy grown in the U.S. is GMO to resist herbicides. Soy based formula contains a daily dose equivalent of 5 birth control pills of estrogen. 

Tap Water - Chlorine and Flouride (in many municiple water supplies).

Other known agents are:

Tobacco,

Radiation

Benzene,

Asbestos

Solvents

Some Drugs

Hormones

Gasoline Exhaust

Pesticides

Air pollutants

Most cancer is not born, but made.

Sources & References:

 http://articles.mercola.com/sites/articles/archive/2010/09/18/soy-can-damage-your-health.aspx
 http://articles.mercola.com/sites/articles/archive/2008/09/09/off-target-in-the-war-on-cancer.aspx
 http://articles.mercola.com/sites/articles/archive/2006/05/27/raise-your-cancer-risks-by-drinking-tap-water.aspx