Everyone is familiar with the word cancer. But, if anyone was asked, “What is cancer?” most of us would have a difficult time answering. Part of the difficulty stems from the fact that cancer refers to more than a hundred different diseases. All of these diseases have one thing in common: cells that divide and grow abnormally. Normal cells keep a balance between cell growth and death, cancerous cells multiply in an uninhibited fashion, or they don’t die off when they become old and damaged. This uninhibited growth and failure to die results in the formation of tumors. Tumors are growths that develop where cells are abnormally dividing. Tumors tend to take nutrients away from normal cells, cause compression and affect the ability of cells to function. This eventually results in a failure of the organ where the tumor is growing. In lung cancer, for example, the tumor may block airways and cause difficulty with breathing. Even if an airway is not directly blocked, the lung will not expand easily and normal exchange of oxygen and carbon dioxide will be hampered. It would be bad enough if cancers just destroyed the organ in which they began, but tumor cells also spread to other parts of the body. They do this in two ways. The first occurs when the tumor grows through the walls of the organ in which it begins. The tumor cells then begin to grow in the nearby structures and organs. A second way that tumors spread is by entering the lymph and blood systems. When tumor cells enter either of these systems, it can spread the cancer to very distant areas of the body. Thus, a person with lung or breast cancer can develop tumors in many other areas such as their bones, liver or brain. Cancer Screening The idea behind screening is to detect cancers before it has the opportunity to spread beyond the original site. Early detection of cancer is difficult since there usually aren’t any symptoms. Cancer screening greatly enhances the chance of finding cancer at an early stage. Most cancers are more easily treated and cured if they are found early. Many of the treatments we use for cancer are based on our knowledge about how the cancer cells behave. Most of the current standard therapies like radiation and chemotherapy treatments are designed to kill rapidly dividing cells. Unfortunately, they also affect some normal cells that tend to replicate quickly like hair and the mucous membranes of the mouth and digestive tract. A newer treatment can prevent the tumor from developing its own supply of blood vessels. Treatments may also inhibit the proteins that trigger cell division for particular types of cells. These treatments are more likely to affect only cancer cells with fewer side effects, but also tend to be developed with particular types of cancers in mind. An example of this is a drug called Gleevec, which was recently approved by the FDA for several type of leukemia. It has proved to be useful for a couple of other types of cancer, but because of its specific action it will not be a cure-all for most cancers. Marva Bohen is a member of the University’s Cancer Center. To learn more about cancer, visit www.cancer.umn.edu or call the information line at (888) CANCER MN (226-2376). This column is an educational service and advice presented should not take the place of an examination by a health-care professional. To ask a health-care expert at the university a question or for more health-related information, go to www.healthtalk andyou.com.
