This has always puzzled me

[EternalOptimist]

If I understand it correctly, Cancer occurs when your cells start to produce other cells that are wonky, and it becomes malignant when the wonky cells start to produce other wonky cells.

If that is true why is there such a strong link between smoking and lung cancers ? Why dont you get cancers when ciggie smoke gets on your skin or in your hair or eyes ? Is it something to do with the lungs ?

[TheBigYinJames]

If that is true why is there such a strong link between smoking and lung cancers ? Why dont you get cancers when ciggie smoke gets on your skin or in your hair or eyes ? Is it something to do with the lungs ?

I don't think the mechanism is totally understood, but it's to do with damage. When you damage an area, it is forced to heal, and thus the cells have to reproduce far more quickly than they would during normal 'maintenance' replacement. So your chances of one cell going wonky are greatly increased. Smoking damages the lining of the lungs, continually over the years, forcing continual rapid healing and cell multiplication. The rest is statistics.

[DaveB]

If I understand it correctly, Cancer occurs when your cells start to produce other cells that are wonky, and it becomes malignant when the wonky cells start to produce other wonky cells.

If that is true why is there such a strong link between smoking and lung cancers ? Why dont you get cancers when ciggie smoke gets on your skin or in your hair or eyes ? Is it something to do with the lungs ?

It also causes cancers in the mouth and throat and is a strong risk factor in other cancers, particularly bowl and bladder. It's to do with the way the carcinogens in the smoke get into your body. The higher the concentration the more likely the cancer is to occur.

Hair is essentially dead and has no mechnaism for transferring anything into the body, skin is pretty much impermeable to most things ( it has to be ) and your eyes get regularly rinsed out every time you blink or your eyes water.

[EternalOptimist]

I don't think the mechanism is totally understood, but it's to do with damage. When you damage an area, it is forced to heal, and thus the cells have to reproduce far more quickly than they would during normal 'maintenance' replacement. So your chances of one cell going wonky are greatly increased. Smoking damages the lining of the lungs, continually over the years, forcing continual rapid healing and cell multiplication. The rest is statistics.

I suppose that would explain other observations like increased cancers in older people, increased breast cancer in large bosomed women etc

[EternalOptimist]

It also causes cancers in the mouth and throat and is a strong risk factor in other cancers, particularly bowl and bladder. It's to do with the way the carcinogens in the smoke get into your body. The higher the concentration the more likely the cancer is to occur.

Hair is essentially dead and has no mechnaism for transferring anything into the body, skin is pretty much impermeable to most things ( it has to be ) and your eyes get regularly rinsed out every time you blink or your eyes water.

exactly. What has permeability got to do with it ? thats what I want to know.

[BoredBloke]

I think it is to do with the concentration. When you inhale smoke you get a fairly concentrated mix of chemicals in your mouth, throat and lungs. When you exhale this mix gets thinned out in the air, so the amount touching your skin will be tiny. Also, your skin is designed to repell things - the litle air sacks in your lungs are designed to allow the free transfer of gasses - so it is easier for the dodgy stuff in cig smoke to get into them.

but then I might well be talking bollox!

[Churchill]

I've always thought of cancer as a type of binary poison.

You need a mixture of circumstances to initiate it.

[DaveB]

exactly. What has permeability got to do with it ? thats what I want to know.

The surfaces in your mouth, throat and gut are far more permeable than the skin on the outside so the carcinogens can permeate into the cells there. From there they get into the blood stream and end up in the liver, from there to the kidneys and finally the bladder where they swill around waiting for you to take a piss.

The lungs are the most permeable suface of all because they have to be in order for you to be able to breath, so they get the highest concentrations of the carcinogens, hence lung cancer being the most prevelent form in smokers. If you smoke you are far more likely to get cancer of any form but chances are if you do it will be lung cancer.

[DaveB]

Excerpt from the results of a study into incidence rate of cancer among smokers over a 22 year period. The results were published back in 1992.

To determine the attributable risk of cancer due to cigarette smoking, Chyou and colleagues obtained a smoking history from 8,006 men of Japanese ancestry who were examined from 1965 through 1968 on the Hawaiian island of Oahu.

After continuous follow-up of the study population for 22 years, 1,389 incident cases of cancer were identified by tissue confirmation. A total of 212 men hand lung cancer, 202 men had oral-bladder cancer (esophageal, laryngeal, pancreatic, renal, ureteral for bladder cancer), and 975 men had cancer at other sites. As in previous cancer mortality studies, current smokers were found to have an almost two times greater risk of cancer than nonsmokers. Former smokers were at only slightly increased risk for cancer (relative risk of 1.2). Twenty-six percent of all cancer cases were attributable to cigarette smoking. Comparison of current smokers with men who had never smoked showed that 85 percent of lung cancers, 46 percent of oral-bladder cancers and 29 percent of all cancers combined would have been avoided if current smokers had never smoked cigarettes.

The study findings underscore the devastating effect of cigarette smoking on cancer incidence and cancer mortality, especially with regard to lung cancer. The data indicate that current smokers can significantly reduce their risk of cancer by quitting smoking. The authors strongly recommend increased development of smoking cessation programs that enable current smokers to stop smoking forever. (American Journal of Public Health, January 1992, vol. 82, p. 37.)

[TimberWolf]

If I understand it correctly, Cancer occurs when your cells start to produce other cells that are wonky, and it becomes malignant when the wonky cells start to produce other wonky cells.

If that is true why is there such a strong link between smoking and lung cancers ? Why dont you get cancers when ciggie smoke gets on your skin or in your hair or eyes ? Is it something to do with the lungs ?

The lungs can't shift tar once it's in the lungs, apparently (need a reference), and you can tell in an autopsy that someone was ever a smoker, since their lungs remain full of tar for life. Seems a bit weird that they are not also full of atomic sized house dust particles too though (larger stuff is trapped and removed). Chronic inflammation is also often bad news despite it being (possibly) good in the short term. Tar can give you cancer anywhere I believe.