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•Certain normal genes involved in cell growth, development, and differentiation can be converted into cancer-causing "oncogenes" by mutation. Other genes that normally prevent the uncontrolled growth of cells "suppressor" genes can also produce cancer if they are knocked out by genetic mutations.•Single mutations are generally not sufficient to cause cancer, but they produce changes that may predispose cells to malignant growth. Additional mutations in other genes, caused by damage from the environment, continue the cells' malignant transformation. Thus, cancer is a multi-step process involving the interaction between genes and their environment.Cancer As a Genetic Disease
•Nearly all cancers are caused by abnormalities in the genetic material of the transformed cells. These abnormalities may be due to:1.Inheritance, and thus present in all cells from birth. The heritability of cancers are usually affected by complex interactions between carcinogens and the host's genome 2.Effects of carcinogens, such as tobacco smoke, radiation, chemicals, or infectious agents. 3.Error in DNA replication (randomly acquired).
Cancer as a Global Health Problem•In the year 2000, malignant tumors were responsible for 12 percent of the nearly 56 million deaths worldwide from all causes. In many countries, more than a quarter of deaths are attributable to cancer. In 2000, 5.3 million men and 4.7 million women developed a malignant tumor and altogether 6.2 million died from the disease. •The predicted sharp increase in new cases from 10 million new cases globally in 2000, to 15 million in 2020 will mainly be due to steadily ageing populations in both developed and developing countries and also to current trends in smoking prevalence and the growing adoption of unhealthy lifestyles.
Risk Factor•A risk factoris anything that increases a person's chance of getting a disease. Some risk factors can be changed, and others cannot. •Risk factors for cancer can include a person's age, sex, and family medical history. Others are linked to cancer-causing factors in the environment. Still others are related to lifestyle choices such as tobacco and alcohol use, diet, and sun exposure.
Cancersof the lung, mouth, larynx, bladder, kidney, cervix, esophagus, and pancreas are related to tobacco use, including cigarettes, cigars, chewing tobacco, and snuff. Smoking alone causes one-third of all cancer deaths.Skin canceris related to unprotected exposure to strong sunlight.Breast cancer riskfactors include several factors: age; changes in hormone levels throughout life, such as age at first menstruation, number of pregnancies, and age at menopause; obesity; and physical activity. Also, women with a mother or sister who have had breast cancer are more likely to develop the disease.Prostate cancer riskinclude:•Age, race, and diet •Older age •Prostate cancer is more common among African-American men than among white men. •High-fat diet •Men with a father or brother who have had prostate cancer are more likely to get it.
Risk Factors For Cancer•Old age•Environmental factors, defined broadly to include tobacco use, diet, infectious diseases and sunlight.