Breast cancer screening

The health piece Many Women Treated Needlessly For Breast Cancer (July 13) picked up an AFP report in connection with a study by Scandinavian experts that highlights the benefits and hazards involved in screening for breast cancer. The study was published in the British Medical Journal.

The experts found that doctors detected more cases of breast cancer but also treated more women who would not have needed it. They estimated that one in three cases of breast cancer detected in a population offered organised screening, is over-diagnosed. Because doctors have no idea whether the cancer will be lethal or harmless they tend to treat all patients diagnosed with a tumour. But cancer treatment, using powerful drugs, radiotherapy or surgery causes harm.

In an editorial that appeared in the same edition of BMJ, H. Gilbert Welch, a professor at the Dartmouth Institute for Health Policy and Clinical Research in Vermont, is reported to have called on the medical profession to draw up a simple statistical table to help women weigh the risks and benefits from breast cancer treatment. He is quoted to have said: "Mammography undoubtedly helps some women but hurts others... No right answer exists... instead it is a personal choice".

Over-diagnosis is an acknowledged problem with screening mammography. For some people it may be both unnecessary and intrinsically harmful in its own right. The danger of a false positive reading, with all the attendant anxiety and ensuing interventions, is always a risk in current mammography programmes.

Similarly, the real possibility of a false negative, meaning a clean bill of health that turns out to be illusory, is inherent in screening mammography. Moreover, there is no guarantee that a breast cancer identified by screening mammography will be curable.

A very important but largely ignored factor is the radiation inherent in screening mammography. It is well documented that screening mammography exposes the breast tissue to repeated doses of low-energy X-rays. A study performed at Columbia University's Centre for Radiological Research shows that lower-energy X-rays may actually be more damaging to DNA than their high-energy counterparts (Brenner 2000).

Additionally, physical compression of the breast, which is necessary to obtain a readable radiographic image, can result in the rupture of small blood and lymphatic vessels in close proximity to the tumour, thus releasing malignant cells into the general circulation (Rosser, The Medical Journal, The Breast, 2000).

It is often fear that drives women to screening mammography, a fear that is fostered by some members of the medical profession and a highly screening industry that are doing little to inform women of the real risks and gain they can really expect from screening mammography.

Cornelia J. Baines, director of the prestigious Canadian National Breast Screening Study and the author of 70 Pub-Med-listed journal articles, puts it thus: "I remain convinced that the current enthusiasm for screening is based more on fear, false hope and greed... than on evidence" (Baines, 2005).

Women face a difficult choice and need to make sure they understand that their decision carries dire consequences in both directions. It is hoped that the national breast cancer screening reportedly scheduled for a "kick-off" in a short time will not foster a climate where women are seen irresponsible if they do not undergo screening.

I trust that our dedicated multi-disciplinary breast team at Mater Dei Hospital will follow the guidelines suggested by Prof. Welch, meaning that women are offered a simple statistical table that spells out the risks and the benefits from breast cancer screening. I am in no doubt that our breast cancer NGOs will leave no stone unturned in offering sound guidance.