1.56. Cancer http://www.ck12.org
1.56 Cancer
- Describe causes and treatments of cancer.
Why is tanning bad for your health?
It might be fun to lay out in the sun like these two girls are doing. But getting too much sun can be very dangerous.
Overexposure to sunlight raises your risk for skin cancer.
Cancer
Canceris a disease that causes cells to divide out of control. Normally, the body has systems that prevent cells from
dividing out of control. But in the case of cancer, these systems fail.
Cancer is usually caused by mutations.Mutationsare random errors in genes. Mutations that lead to cancer usually
happen to genes that control the cell cycle. Because of the mutations, abnormal cells divide uncontrollably. This
often leads to the development of a tumor. Atumoris a mass of abnormal tissue. As a tumor grows, it may harm
normal tissues around it.
Anything that can cause cancer is called acarcinogen. Carcinogens may be pathogens, chemicals, or radiation.
Pathogens
Pathogens that cause cancer include the human papilloma virus (HPV) (Figure1.112) and the hepatitis B virus.
HPV is spread through sexual contact. It can cause cancer of the reproductive system in females. The hepatitis B
virus is spread through sexual contact or contact with blood containing the virus. It can cause cancer of the liver.