Six months ago, at the age of 39, I was diagnosed as having rectal cancer. Since then I have had the opportunity to consider the array of risk assessments and statistics that the medical profession presents to patients.

Because my father had a large bowel malignancy in his 50s, when I had a single episode of rectal bleeding I referred myself directly to a colorectal surgeon. He immediately diagnosed a small rectal lesion, which appeared clinically to be malignant. Following appropriate investigations I underwent major surgery. The risks of such pelvic surgery were clearly explained and I consented to the surgery–I had no realistic choice. But when I subsequently had a variety of unwanted after-effects I was able to recognise that, despite my training and knowledge, I had dealt with the risk of side effects by assuming that they would not happen to me.

Then things got more complicated. The tumour had appeared–and indeed was–very localised with minimal invasion of muscle, but the nearest lymph node (out of 17 …