Guidance issued to UK operators in 1992 recommends a mammogram force limit of 200 newtons per breast during mammography the equivalent of 20 kilo bags of sugar and some of the modern foot pedal operated machines are capable of delivering up to 300 newtons.

Given the level of force involved, it is not surprising that more than a third of women experience pain or discomfort during the process (D Rutter et al, BMJ 1992; 305 443-5).

British medical opinion continues to downplay the importance of physical examination, which has no known side effects, in favour of mammography, which has plenty. This attitude was compounded last year when outgoing chief medical officer, Sir Donald Acheson, in a series of off the cuff remarks at a press conference, condemned self examination as a waste of time. Acheson's pronouncements, which received wide publicity, were apparently based on nothing more than his own personal prejudices, and contradicted the evidence of numerous studies and the guidance being issued by his own department. Health officials moved quickly to try to repair the damage done by his remarks by talking about the need for general "breast awareness", rather than actual examination confusing everyone even more.

Others were less concerned with saving Acheson's face and more concerned about saving women's breasts. Writing to the Times soon after Acheson's comments (23 September 1991), Roger Taylor, consultant clinical oncologist at Cookridge Hospital's regional radiotherapy centre, said: "Some cancers which can be felt on clinical examination are undetected by a mammogram."

Dr Joan Austoker, an adviser to Dr Kenneth Calman Acheson's successor, told the Sunday Times (6 October 1991): "What [Acheson] did not say is that more than 90 per cent of breast tumours are found by the women themselves."

A seven year study of 33,000 women by the Pennine Breast Screening Assessment Clinic in Huddersfield, published the week after Acheson's comments and reported in the Times (20 September 1991) showed that self examination could reduce breast cancer deaths by up to one fifth.

A benign lump and nine out of ten are benign is best left alone. If, however, there is good reason for further examination, you are likely to be offered some form of biopsy.

Biopsies tend to be treated as routine and minor by doctors. For the women concerned, they are anything but and should only be undergone if strictly necessary. In a standard biopsy, a thickish needle is inserted into the breast, under local anaesthetic, to remove a small piece of tissue which will then be examined for cancerous cells.

A study of 104 women undergoing biopsy for what proved to be benign lumps found that a quarter of them had "wound related morbidity" (disease) afterwards (J Dixon and T John, The Lancet, 11 January 1992). Nine patients reported that a new breast lump had developed under the biopsy scar between one to seven years after surgery. In each case, this new lump was investigated and, again, found to be benign. Eight patients had pain in the biopsy area one to six years after the procedure.

The authors of the report conclude that greater use should be made of fine needle aspiration. In this less invasive procedure, which can be done on an outpatient basis, a fine needle with a syringe is inserted in the breast to draw out a specimen of its contents. It is not without its complications, however. The BMJ (12 October 1991) cites cases of patients suffering pneumothorax (where air enters the chest, causing the lung to collapse) after needle aspiration. So you should be alert to symptoms of chest pain and breathing difficulty after needle aspiration and seek immediate medical help.