Carcinogens and Other Contributing Factors

Carcinogens (cancer “causing” agents) affect cells at the DNA level They can change proto-oncogenes into oncogenes They can affect the “good” defenses during neoplastic transformation

Carcinogen?

Contributing Factors to Cancer: 1. Genetics: Some people are more susceptible to specific carcinogens

Ex. About 10% of breast cancers are inherited Mutation in either the BRCA 1 or BRCA 2 gene

2. Electrolyte exposure: Electrolytes: any substance containing free ions that behave as an electrically conducive medium Act as free radicals Exposure to high concentrations of specific metal ions

Nickel

3. Carcinogenic chemical exposure There are over 600 chemicals found in human tissue that are not part of our bodies Many of these act as free radicals Examples: cigarette smoke, pesticides---DDT, insulation (asbestos)

Build up of normal background radiation over many years of exposure X-ray, uranium, plutonium exposure Ex. Chernobyl

5. Chronic Sub-lethal Tissue Damage: Tissue is damaged enough to form a tumor, but not enough for cell death to occur Ex. Polyps—constant irritation

6. Viruses: Viruses interact with the cell’s DNA and can lead to neoplastic transformation Ex. HPV, Epstein Bar Virus, hepatitis

7. Hormonal Imbalances: Too much of a hormone can influence the production of neoplasms 20% of breast cancers are hormonally sensitive

In the 1940s, researchers found that mixing synthetic estrogen into the cattle feed resulted in the cows gaining weight faster Ranchers found that the cows did not miscarry when given the hormone

Doctors began prescribing it for pregnant women (called DES) Women gave birth to healthy children…however When the female babies reached puberty, doctors began to see many cases of infertility and vaginal cancer