A SURPRISING proportion of my friends and acquaintances are starting this New Year facing recent cancer diagnoses. In general, these are the common cancers, breast, colon, and prostate, but there are some rarer ones, too.

I was intrigued by last week's report, from American scientists, that two-thirds of cancers cannot be explained by genetics or poor lifestyle, but are a matter of pure bad lack. The constant process of cell-copying and division by which body tissues are renewed occasionally goes wrong, and mutations occur. These are simple accidents, inherently unpredictable. The older you get, the more likely it is that something will go wrong. That is not an excuse for giving up your five a day, or taking up smoking. Bad habits play a part, but not as much as we have been encouraged to think; and not in all cancers.

The random nature of the mutations that lead to cancer poses a big challenge. We have become so used to thinking that there is a reason for everything that we are frustrated by the unreasonableness of this particular disease. Deep down, we can't quite cope with chance; reason is our comforter. We like to have a named cause, and even the possibility of finding someone, or something, to blame. I have always assumed that, should I contract cancer (and by now I probably have a few chance mutations hovering around), it would be traceable to a near relative, or the result of my own idleness or over-indulgence. But, if I can't blame it on my genes or on my lifestyle, reason is left flailing about in a sea of probabilities and statistics.

Curiously, I find this more liberating than worrying. I can't bear the constant pressure to be perfect in body and mind - the crazy belief that we can extend our lives indefinitely by exercising will-power. In the wider picture, the idea that we bring all our illnesses on ourselves is gross. We accept it only because it makes us feel we are in control. But the price of such control is too high. It leaves us in a psychological purgatory, swinging constantly between guilt and self-righteousness.

If most cancers are down to rotten bad luck, that affects any tendency we may have to think of God as one who pays us back for our bodily sins by sending bodily punishments. God's universe is not a penitentiary, but an experiment in freedom. Cancer-sufferers are involuntary load-bearers: they bear some of the burden of a creation that is struggling to find God's freedom and fulfilment.

The Revd Angela Tilby is Diocesan Canon of Christ Church, Oxford, and Continuing Ministerial Development Adviser for the diocese of Oxford.