In the performance of analytical studies epidemiologists move from the demanding chores of collecting accurate information into the realms of designing studies that seek to answer important individual questions about the causes of cancer. In this area they will usually have an idea to test – a hypothesis about some possible causative factor. The focus shifts from whole nations or whole regions to a much more closely defined group of individuals. By collecting a great deal more information about a rather smaller number of people (but not so small that our conclusions might be based on pure chance), it is possible not only to demonstrate links between particular factors and particular cancers but also to look carefully to see if there are any possible alternative links which have to be considered or excluded by careful work. A number of methods of performing analytical epidemiology are recognized and are worth mentioning to give the general flavour of this sort of work: cohort studies, case-control studies and intervention or experimental studies.
Case-control Studies. In this method the group of people about whom information is collected are those who are already suffering from the particular cancer. They are then matched to another group of people who do not have the cancer but who are similar in other aspects such as age, sex and often social group. The group of patients with the cancer (the cases) are then compared to the group who do not have the cancer (the controls) in terms of their previous exposures to all sorts of factors. If the cases have had more exposure to a particular factor than the controls, it suggests that that particular factor is linked to the cancer. Again, it sounds easy bur collecting the information is a laborious task and choosing controls is full of pitfalls. If the groups are not properly matched then misleading links can be suggested. A particular pitfall is choosing groups of people when they come to hospital. Hospital-based control groups may be very unrepresentative of the general population.
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Archive for June, 2011
“There are traffic lights longerthan my social life,” Jake said wearily when he met with me. “This problem is ruining my life. It’s like fighting demons.”‘
Jake was preoccupied with his arms and legs, which he thought were too skinny, and his “pale” skin. “I have no sex life or love life. I’m almost completely socially avoidant. I hardly ever go out. If I do go to a night club, I feel suicidal. … I’m still in shock that I look so horrible after all these years. It amazes me that no one faints when I get on the subway!”
Jake had been married to someone he hated and later divorced. “I married someone I felt no desire for. She was an awful person, but she was the only one who would accept me. She was probably the worst woman in the whole world, but I didn’t think anyone else would accept me because of how I look. I felt lucky to have anyone.”
Samantha avoided swimming or any activities requiring shorts. She, too, was concerned with pale skin and with freckles on her arms, legs, chest, and back. “The color of my skin is dead looking,” she said. “It causes problems in my social life. I miss parties sometimes, and if I go I can’t focus on conversations because I’m thinking about my freckles and pale skin. I’m constantly scrutinizing other people’s skin. I’m noticing what a nice color it is, or that they don’t have any freckles. The only time I really tune into the conversation is when I hear anything about freckles or skin. Then my ears perk up. “This problem also interferes with my sex life. My husband told me to make sure I told you. I feel very self-conscious, and I don’t want him to see my body. I can’t relax and enjoy anything. My husband can’t understand me. He tries but he can’t, and he gets angry about it.”
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Improper diet, insufficient exercise, stress, overeating and ignoring the call of nature can all lead to bowel problems. Fibre-rich food is not the complete answer. Some people eat lots of bran (usually wheat bran, and 30 per cent of people are wheat intolerant); wheat scours the delicate lining of the bowel, and if the person is constipated it will make the condition worse by achieving nothing other than an irritable bowel and lots of flatulence.
Fibre is the bit that is left behind once the food is digested. It is considered good for us because it helps to provide bulk to otherwise watery wastes in the colon, and absorbs toxicity; but it is no good if the colon is already prone to blockage. Like the rest of the waste, some types of fibre will become stagnant and add to the congestion.
Better alternatives to bran are roughage from other vegetable bases, such as oats and rice. These tend not to be so abrasive and to swell into a mucilaginous gel which acts as a gentle detoxifier.
One common sign of trouble, dense sticky bowel movements, indicates an excess of mucus in the system. This is usually the product of mucus-producing foods such as dairy products, flour and meat. Meat is extremely contaminating to the bowel and prone to putrefaction, and in a short time creates a great strain on the elimination system.
Mucus stools are the most difficult to eliminate. They leave behind the glue-like coating on the wall of the colon which accumulates layer upon layer into a hard rubbery crust. This is carried for the duration of the person’s life as a toxic burden.
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