Some cancers are genetic in origin and therefore no amount of action can produce any improvement.

Being involved in a car accident may be considered sheer bad luck, but we would all agree that the odds of being involved are far greater if we happen to be driving in a state of intoxication.

It is also bad luck to be born with a hereditary change in your DNA which may be responsible for causing cancer 30 or 40 years later. Some cancers, including those affecting the breast or colon, have been shown to belong to this category.

It is, however, rather challenging to read, in a recent publication from no less an institution than the Johns Hopkins School of medicine, that fully one-third of cancers are due to bad luck.

This is a damning conclusion, implying that whatever we do and however careful we look at our diet, irrespective of the degree of exercise we force our body into, given time, many of us will develop cancer.

Cancer is not one disease but many different kinds. Different cancers affect different organs, like the colon or skin or bone marrow for reasons that are not often clear at all. They develop and move at various rates, some explosively, other very, very, slowly.

But what they all have in common is a fundamental change in the DNA (a so-called ‘mutation’) whereby that particular cell obtains the potential to behave in a bizarre and disorderly fashion – but only the potential. We all have mutations in some of our cells for some of the time. Some of these lie hidden and inactive, others decide to take off and produce cancer.

It is rather important to realise that simply having a mutation is not akin to having cancer. A cell with such ‘latent’ damage can be pushed into activity and be propelled into its inexorable path to malignancy. So what makes a cell harbouring a mutation become a cancer cell?

Cancer is not one disease but many different kinds. Different cancers affect different organs

We have learned quite a bit about the basic biology of cancer cells. We are now quite clear in our minds that certain agents, such as radiation (whether it is in the form of X-rays or solar radiation), or smoking , for example, can not only cause mutations, but can also induce a mutated cell to evolve and become manifest as a cancer cell. We can say that such agents can both ‘initiate’ a DNA mutation, as well as ‘promote’ such mutations to develop into overt cancer.

On the other hand, while there is a clear association between obesity and cancer of, say, breast or colon, there is no clear-cut evidence that fat is carcinogenic (i.e. cancer-producing).

There is also plenty of evidence that chronic irritation, trauma or hormone stimulation (by oestrogens, for example) may result eventually in cancer. While it is unlikely that they are actually causing new mutations, it is more likely that they act by promoting the progress of mutations which happen to be lurking in one or other organ in the body.

Should this news, namely that getting cancer can be the luck of the draw, lead to a state of despair, giving up our efforts to reduce the risk?

A number of very common cancers, which account for a considerable proportion of the total cancer load within the community, are very commonly the result of our way of life, and can be avoided. The incidence of one of the commonest lung cancer, would be at least halved if everybody in the community stopped smoking. Another very common cancer, namely colon cancer, would certainly be decimated if standard precautions relating to diet (including high fibre, low meat) were adhered to. There are whole continents in the world where cancer of the colon hardly exists. Likewise, cancer of the skin would certainly be reduced considerably if reasonable precautions for avoiding solar radiation were put in place.

There is also no doubt that an increased body weight is related to a higher incidence of breast cancer, the commonest cancer in women. While a relatively small proportion of breast cancers (about 10 per cent) are genetic in origin, the vast majority are more likely to be environmental in origin and therefore controllable, at least in theory.

So it’s good news and bad news. Some cancers are genetic in origin and therefore no amount of action by individuals or health organisations can produce any improvement in the situation.

Whether one gets these cancers of not is indeed a question of luck. Our only hope is to detect them early through rigorous screening of those at risk.

On the other hand, a large number of quite common cancers result from, or are made worse through, our own activities.

It is here where emphasis and public education should be placed.

Luck hardly plays any significant role in this type of cancer.