Background: Cancer is 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. Mutations are 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. A tumor is a mass of abnormal tissue. As a tumor grows, it may harm normal tissues around it. Anything that can cause cancer is called a carcinogen . Carcinogens may be pathogens, chemicals, or radiation.

Situation: Ann noticed a lump in her breast when showering. Concerned she went to see her doctor. The doctor sent her for a mammogram and some blood work. Eventually Ann was diagnosed with breast cancer.

Question: Was the lump Ann felt a tumor or a cyst?

Situation: Ann noticed a lump in her breast when showering. Concerned she went to see her doctor. The doctor sent her for a mammogram and some blood work. Eventually Ann was diagnosed with breast cancer.

Question: Were Ann's cells multiplying or dying?

Situation: Ann noticed a lump in her breast when showering. Concerned she went to see her doctor. The doctor sent her for a mammogram and some blood work. Eventually Ann was diagnosed with breast cancer.

Question: Untreated will the umor grow or shrink?

Situation: Ann noticed a lump in her breast when showering. Concerned she went to see her doctor. The doctor sent her for a mammogram and some blood work. Eventually Ann was diagnosed with breast cancer.

Question: Were normal or abnormal cells dividing?

Situation: Ann noticed a lump in her breast when showering. Concerned she went to see her doctor. The doctor sent her for a mammogram and some blood work. Eventually Ann was diagnosed with breast cancer.

Question: Was the cell division under control or out of control?

Situation: Mark had smoked a pack of cigarettes every day for 20 years. He tried to quit smoking several times but had never been successful until now.  Recently Mark had been having trouble breath and gone to the doctors. Mark's doctor found a tumor on his left lung.

Question: What carcinogen was Mark exposed to?

Situation: Mark had smoked a pack of cigarettes every day for 20 years. He tried to quit smoking several times but had never been successful until now.  Recently Mark had been having trouble breath and gone to the doctors. Mark's doctor found a tumor on his left lung.

Question: Where cells in Mark's body dividing normally or abnormally?

Situation: Mark had smoked a pack of cigarettes every day for 20 years. He tried to quit smoking several times but had never been successful until now.  Recently Mark had been having trouble breath and gone to the doctors. Mark's doctor found a tumor on his left lung.

Question: Is the tumor a mass of normal or abnormal tissue?

Situation: Mark had smoked a pack of cigarettes every day for 20 years. He tried to quit smoking several times but had never been successful until now.  Recently Mark had been having trouble breath and gone to the doctors. Mark's doctor found a tumor on his left lung.

Question: Will tumor harm or repair the tissue around it?

Situation: Mark had smoked a pack of cigarettes every day for 20 years. He tried to quit smoking several times but had never been successful until now.  Recently Mark had been having trouble breath and gone to the doctors. Mark's doctor found a tumor on his left lung.

Question: Are Mark's genes normal or mutated?

Situation: Mark had smoked a pack of cigarettes every day for 20 years. He tried to quit smoking several times but had never been successful until now.  Recently Mark had been having trouble breath and gone to the doctors. Mark's doctor found a tumor on his left lung.

Question: Was the mutation in Mark's genes planned or random?