Mens Health Blog. Medical Blog » Cancer

HOW DO WE KNOW SMOKING CAUSES LUNG CANCER?

admin — Fri, 15 Jul 2011 08:46:34 +0000

Unravelling the link between smoking and lung cancer has been one of the most successful exercises in the science of epidemiology. The part played by British scientific workers, most notably Sir Richard Doll from the University of Oxford, has been one of the most substantial contributions of British science to medicine. • Through this century the upward trend in lung cancer has followed the upward trend in smoking closely.• The incidence of lung cancer is higher in smokers. A large number of studies in analytical epidemiology all point in the same direction.• The more you smoke the more likely you are to get lung cancer. This is true for the duration of smoking and the number of cigarettes smoked. The exact relationship between the number of cigarettes smoked and the increased risk of lung cancer can still be debated. People have smoked in different ways in different countries and discarded different amounts of the cigarettes. The tar content of cigarettes varies greatly and has fallen steadily in cigarettes smoked in Western Europe and the United States.A recent estimate from the United States (report of the Surgeon General, 1989) says that regular cigarette smokers have more than a twenty times greater chance of getting lung cancer than lifelong non-smokers. The relationship between the number of cigarettes smoked and the risk is not a simple straight line. We cannot be precise about the relationship but Sir Richard Doll and his colleagues suggest that the likelihood of getting cancer from cigarette smoking rises according to a more complicated mathematical relationship known as a quadratic. Broadly this will mean that increasing the number of cigarettes smoked may have a disproportionate effect on the chance of getting lung Cancer.• When you stop smoking your chance of gating lung cancer falls. Within ten years the risk has fallen dramatically from what it would have been if smoking had continued although it may take quite a long time to return to the very small level of risk enjoyed by non-smokers.• Smoking low-tar cigarettes reduces the risk of lung cancer. This is strong evidence because most other factors about the two groups – those using high-tar and those using low-tar cigarettes – will be similar. Only the change in the level of tar in cigarettes is likely to explain the change in lung cancer incidence which in low-tar smokers is reduced to about 60 per cent of the risk for patients smoking high-tar cigarettes.• Chemicals in cigarette tar are mutagenic and carcinogenic. By this we mean that such chemicals alter genes and have been shown in the laboratory to produce cancer.*40\194\4*

CANCER: FAMILY HISTORY AND OTHER CAUSES OF MELANOMA

admin — Mon, 03 Jan 2011 16:15:46 +0000

Determining the cause of malignant melanoma is one of the most pressing problems in cancer research today. A family history of melanoma seems to be an additional risk factor. Approximately 10 per cent of cases of melanoma occur in people with a familial predisposition, and some of these will have the unusual moles called dysplastic naevi. Work on the genetics of inherited melanoma is so far incomplete, but there does seem to be a probability of a gene or chromosome which influences the risk of getting cutaneous malignant melanoma.

Other Factors. Early studies suggested the possibility of a link between malignant melanoma and the contraceptive pill, as well as a range of other factors. However, recent, well-designed and very careful studies have shown that there is no important influence of diet, alcohol, coffee, smoking, bathing habits, hair dyes, fluorescent light or the contraceptive pill on the risk of getting a melanoma. These were important possible links to explore but they are now to be discarded.

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CANCER: FAMILY HISTORY AND OTHER CAUSES OF MELANOMADetermining the cause of malignant melanoma is one of the most pressing problems in cancer research today. A family history of melanoma seems to be an additional risk factor. Approximately 10 per cent of cases of melanoma occur in people with a familial predisposition, and some of these will have the unusual moles called dysplastic naevi. Work on the genetics of inherited melanoma is so far incomplete, but there does seem to be a probability of a gene or chromosome which influences the risk of getting cutaneous malignant melanoma.Other Factors. Early studies suggested the possibility of a link between malignant melanoma and the contraceptive pill, as well as a range of other factors. However, recent, well-designed and very careful studies have shown that there is no important influence of diet, alcohol, coffee, smoking, bathing habits, hair dyes, fluorescent light or the contraceptive pill on the risk of getting a melanoma. These were important possible links to explore but they are now to be discarded.*72\194\4*

YOUR CANCER YOUR LIFE – CAUSES OF CANCER (TWO IMPORTANT NOTES)

admin — Tue, 12 May 2009 12:09:21 +0000

Firstly, cancer is not inherited. You cannot pass it on to your children, even when cancer develops during pregnancy. There are a few very rare types of childhood cancer which are an exception such as retinoblastoma, a rare cancer of the back of the eye. There are also some rare inherited conditions (such as von Recklinghausen’s disease, xeroderma pigmentosa—ë òàòå skin disease, and some other conditions associated with multiple benign bowel polyps) which are associated with an increased risk of cancer. However, no common type of cancer is inherited. Ask your practitioner about your particular case if you are worried about this.

Secondly, as far as we know, no type of cancer is infectious. No type of cancer can be passed on directly by any form of physical contact, however intimate. However, it is true that some types of infection are linked with some particular types of cancer. For example, many, but not all, patients with a rare cancer called Burkitts’ lymphoma have antibodies to one particular virus, indicating that they have been previously infected by that virus. Many, but by no means all, patients with cancer of the cervix have evidence of previous infection with a certain herpes virus. The cancer called Kaposi’s sarcoma occurs in some patients with

AIDS (Acquired Immune Deficiency Syndrome)— AIDS is caused by a virus. Each of these cancers also occur in patients who have no evidence of previous infection with the particular virus involved. There is not a direct cause and effect relationship—the great majority of people who are infected with these viruses do not get cancer. As with cigarette smoking, it seems that the virus is simply a factor which can operate with other unknown factors to produce cancer in a small proportion of those infected.

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