Separating fact from fiction
When we hear about a particular cancer risk factor in the media, how should we react? How do we decide whether a risk is 'real' or not? And should we change our behaviour accordingly?
Study type
The first thing to consider when reading about a particular risk factor is the type of study. If the report refers only to a study in animals, then scientists will have to do a lot more work to find out if the risk factor affects humans in the same way.
Study size
Similarly, we should look at the size of the study. If the study only involved a small number of individuals (say, fewer than 100), it is possible that the results are due to chance.
Statisticians often refer to a study's 'significance' - this is a technical term for the likelihood of a study's finding being genuine and not due to pure chance. It is very difficult to achieve significant results in studies with fewer than 100 individuals. For greater significance, a study should be looking at more than 1000 people, although this is not always possible for very rare cancers.
Previous studies
Another thing worth considering is whether the study agrees or disagrees with previous studies. If lots of different studies are all pointing in one direction, then it is likely, though not certain, that the risk factor under study is a genuine one. Conversely, if many studies have pointed to a particular risk factor, and a single, solitary study points in the other direction, it might well be an anomaly.
Source
Finally, we should consider where the report comes from. Normally, the studies we read or hear about in the media are taken from papers published in scientific journals. These papers have been checked over by other experts in that particular field before they are published. This is called peer review. Reports that are not taken from peer-reviewed sources are to be treated with a pinch of salt (but not too much salt, of course, as it is a risk factor for heart disease).
If a study meets all the above criteria, it might be that we want to change our lifestyle or behaviour, or see our doctor to discuss the risks. It is always worth remembering, though, that there is a bigger picture than that painted by many such reports. For example, if you are a smoker and want to reduce your risk of lung cancer, eating more fruit will have an effect – but not nearly as big an effect as giving up smoking.
The following things are well-established risk factors for some cancers:
- Tobacco (lung, mouth, throat, voice box, food pipe, liver, pancreas, stomach, kidney, bladder, leukaemia, lymphoma and cervix)
- Alcohol (mouth, throat, food pipe, breast, liver)
- Ultraviolet light (skin)
- Lack of exercise (bowel)
- High fat, low fruit and vegetable diet (bowel)
- Obesity (breast, bowel, womb)
The following things have been reported in the media as cancer risk factors, but have not been confirmed or have been disproved:
- Deodorant
- Underwired bras
- Cuts and bruises
- Make-up
The things you can do that have the greatest impact on your overall health and cancer risk are discussed in the rest of the 'Healthy living' section.
