Treatments for Cancer When a cancerous tumor is localized, it can often be removed by surgery. Skin cancer, the most common form of the disease, can usually be treated this way. Melanomas, the most serious form of skin cancer, can be removed surgically, but only if spotted very early.

Other forms of treatment make use of the fact that cancer cells grow rapidly and, therefore, need to copy their DNA more quickly than do most normal cells. This makes them especially vulnerable to damage from radiation. As a result, many tumors can be effectively treated with carefully targeted beams of radiation.

Medical researchers have worked for years to develop chemical compounds that would kill cancer cells, or at least slow their growth. The use of such compounds against cancer is known as chemotherapy. Great advances in chemotherapy have taken place in recent years and have even made it possible to cure some forms of cancer. However, because most chemotherapy compounds target rapidly dividing cells, they also interfere with cell division in normal, healthy cells. This produces serious side effects in many patients, and it is one of the reasons why scientists are so interested in gaining a better understanding of the role of cell cycle proteins in cancer. The goal of many researchers is to find highly specific ways in which cancer cells can be targeted for destruction while leaving healthy cells unaffected.

Cancer is a serious disease. Understanding and combating cancer remains a major scientific challenge, but scientists at least know where to start. Cancer is a disease of the cell cycle, and conquering cancer will require a much deeper understanding of the processes that control cell division.

FIGURE 10–17 Cancer Incidence Cancer can affect almost every organ in the body. Interpret Graphs How many cases of breast cancer were reported compared to prostate cancer for the time period shown?

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10.3 Assessment

Review Key Concepts

1. 1. Review Name the two types of proteins that regulate the cell cycle. How do these proteins work?

   2. Form a Hypothesis Write a hypothesis about what you think would happen if cyclin were injected into a cell during mitosis. How could you test your hypothesis?

2. 1. Review Why is cancer considered a disease of the cell cycle?

   2. Compare and Contrast How are the growth of a tumor and the repair of a scrape on your knee similar? How are they different?

Apply the Big idea

Growth, Development, and Reproduction

3. Why do you think it is important that cells have a “control system” to regulate the timing of cell division?

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