BREAST SCREENING::The mystery of the disappearing tumours

Mammogram screening is generally agreed to be best practice for all women over the age of 40. It’s supposed to be soon enough to detect early signs of cancer, and so increase the chances for successful treatment. It’s a view that is supported by medical trials, which have concluded that women who have early screening have a lower risk of a recurrence of the tumour and enjoy better survival rates than those who weren’t screened.
Statistics would seem to bear out the theory. In European countries that run early screening programmes, the breast cancer rate is around 50 per cent higher than it was before it was introduced.
All well and good – except it’s not that simple (and if it were, do you really think you’d be reading it in E-News?). Studies from Holland and Britain among women aged between 65 and 69 years have suggested that there is no evidence of a build-up with age of early stage, precancerous tumours. In other words older women seem to have fewer breast tumours than women screened in their 40s.
So – does this mean the tumours just disappear? Amazingly that’s exactly what seems to happen. Scientists from the Norwegian Institute of Public Health believe that subclinical, precancerous tumours are dynamic, and they point to important research among women aged between 50 and 69. In the first screenings, the women displayed three times more preclinical tumours than those who had not been screened – but this fell to just two times the level by the time the same women were closer to 70. For evidence of this, see the European Journal of Cancer, 2004; 40: 2116-25; and the Journal of the American Medical Association, 2004; 291: 824.
It could be that early screening programmes are catching women at a stage when their bodies are producing benign tumours that will spontaneously go into remission.
This suggests one of two things: either screen women as a routine who are much older than 40, or, if tumours are detected in a woman in her 40s, watchful waiting may be a kinder practice than burning, cutting or poisoning.