A risk factor is anything that changes your chance of getting a disease such as cancer. Different cancers have different risk factors. Lifestyle-related risks are thought to be the main factors th\\/’amn/ .l
M;I affect cancer risk in adults. Examples include the effect of unhealthy diets, not enough exercise, and habits like smoking and drinking alcohol. But lifestyle factors usually take many years to influence cancer risk, and they are not thought to play much of a role in childhood cancers.
In recent years, scientists have made great progress in understanding how certain changes in our DNA can cause cells to become cancerous. DNA is the chemical in each of our cells that makes up our genes – the instructions for nearly everything our cells do. We usually look like our parents because they are the source of our DNA. However, DNA affects more than how we look. It also influences our risks for developing certain diseases, including some kinds of cancer.
Some genes (parts of our DNA) contain instructions for controlling when our cells grow and divide. Genes that speed up cell growth and division are called oncogenes. Others that slow down cell division or cause cells to die at the right time are called tumor suppressor genes. Cancers can be caused by DNA changes that turn on oncogenes or turn off tumor suppressor genes.
Some children inherit DNA changes (mutations) from a parent that increase their risk of cancer. These changes are present in every cell of the child's body. This means the changes can often be found by testing the DNA of blood cells or other body cells.
But most cancers are not caused by inherited DNA mutations. They are the result of DNA changes that happened early in the child's life, sometimes even before birth. Every time a cell prepares to divide into 2 new cells, it must copy its DNA. This process is not perfect, and errors sometimes occur, especially when the cells are growing quickly. This kind of gene mutation can happen at any time in life and is called an acquired mutation.
Acquired mutations start in one cell of the body, and that cell passes the mutation on to all the cells that come from it. These acquired mutations are present only in the person's cancer cells and will not be passed on to his or her children. The causes of mutations responsible for certain adult cancers are known (such as cancer-causing chemicals in cigarette smoke), but the reasons for DNA changes that cause the vast majority of childhood cancers are not known. Some may have outside causes that have not yet been found, but most are likely to be random events that sometimes happen inside a cell, without having an outside cause.
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