Researchers have attributed the cause of cancer to two factors: heredity and lifestyle. However, environmental risk factors can alter the cancer rates among adult tissues contribute to the development cancer. Now scientists at Johns Hopkins University have identified a third factor that helps explain why the chances of developing some kinds of cancer such as lung cancer are higher than others such as brain cancer. Cristian Tomasetti, a mathematician who studies oncology, and Bert Vogelstein, a cancer geneticist studied the number of stem cells and their rates of division in 31 different tissues. They discovered that about 65% of the variation in cancer risk among tissue types depends on the number of stem cell divisions a tissue undergoes within its lifetime. The greater the cumulative number of stem cell divisions, the higher the cancer rate in that tissue. It was observed that clorectal and basal cell tissue had the highest number of cell divisions, while bone tissue of the pelvis, head, and arms underwent the least divisions, which affected the likelihood of these tissues developing cancer.
Read more in The Scientist.