How Does Smoking Cause Cancer?
Cigarette smoking causes a significant number of cancers, and it is responsible for about a third of the cancer that occurs in the United States. Discover how smoking can lead to cancer of the lip, mouth, tongue, vocal chords, esophagus, stomach, pancreas, urinary bladder and kidney with help from a pulmonary disease research expert in this free video on the effects of smoking.
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Hello I am Dr. David Burns. I am a Professor Emeritus at The University of California San Diego School of Medicine. Cigarette smoking causes a large number of cancers. It is responsible for about a third of cancer that occurs in the United States. It causes cancer of the lip, mouth, tongue, vocal chords, esophagus, stomach, pancreas, urinary bladder, kidney as well as leukemia and cancer of the cervix in women. Cancer is something that people perceive as a bolt of lightening because that is often the way they feel when the diagnosis is provided by a physician but in reality it is a process that occurs slowly over time. Cigarette smoking contains some 60 or so different cancer causing substances. Those substances are taken into the body, absorbed, transferred into cancer causing substances. Those substances interact with the DNA of different tissues. The DNA is that part of the cell that replicates to create a new cell. When it interacts with the carcinogens that DNA is damaged and so the cell then doesn't replicate exactly accurately. It makes a mistake. Many of those mistakes don't count because they cause the cell to die or disappear but some of them move the cell in the direction of becoming a cancer. Cancer really is a complicated process but in its simplest form it has two clear elements. The first is that a cancer loses the ability to stop growing. If you cut your skin the cells on either side of that cut grow together and when they come to the middle and touch each other they stop growing. If they don't stop growing as occurs in some people the scar will mound up and cause a bump or a tumor called a celoid. The second characteristic of a cancer is that it gains a capacity. It gains the capacity to invade the tissue around it. In contrast to that bump that is a celoid which simply sits there, what a cancer does is it eats away at the tissue around it. It gets into the blood stream and breaks off little pieces that go to other organs and cause metastatic disease and it also can spread to the lymphatic system to other parts of the same organ or even to other organs causing again metastatic disease which damages the brain or the bones or the liver or various other critical organs in the body. So as you smoke one, two, three, ten, twenty, thirty cigarettes a day seven days a week, four weeks a month, twelve months a year, year after year after year, it repetitively is exposing the cells in your body to these cancer causing substances. You are moving those cells step by step by step down the path from being a normal cell towards becoming a cancer cell gaining the capacity to continue to grow and the ability to invade other tissue. Once the cell fully transforms into a cancer it then grows and grows and grows until it creates enough symptoms to cause you to go to the doctor to have that cancer detected. Unfortunately for many cancers that are caused by cigarette smoking by the time the cancer is often detected the cancer is too far along to lead to effective treatment and so there is a very high mortality rate for particularly cancers of the lung, cancers of the esophagus and cancers of the pancreas. The good news is that if you quit smoking over time that risk can change particularly in relation to the other option that you have which is to continuing to smoke. So what you can do is over the course of ten or fifteen years of cessation you can gradually change your risk from that ten times that of a never smoking down to about twice that of someone who never smoked and that, if you quit by age 50 you can avoid many of the adverse risks of developing cancer that occur in individuals who continue to smoke after that age.