Trevor Smith: Breast cancer just one danger of many

Breast cancer awareness month ended yesterday. The Sky Tower was bathed in pink throughout October. Radio and newspapers exhorted women to have mammograms. There were gala evenings to raise funds for research and free public seminars.

Breast cancer has indeed achieved celebrity status. Faced with the barrage of publicity it is not surprising that most women overestimate their personal risk of getting breast cancer.

Fortunately 90 per cent will never get it and only a third of those diagnosed will die from it. We are told that over 2000 new cases are diagnosed annually and 622 women die each year. This is indeed a concern but unpublicised is the fact that 546 women die from lung cancer and a further 563 from bowel cancer annually. Cancer kills 7620 New Zealanders each year, of whom 622 have breast cancer.

These statistics are only a small part of our overall health catastrophe. Ischaemic heart disease, smoking-related illness, diabetes, obesity and other preventable diseases are wreaking havoc.

Few women are aware they have a far greater chance of dying from heart disease (2704 deaths) or a stroke (1620 deaths) than breast cancer. Overzealous campaigning for breast cancer awareness skews funding and prevention initiatives.

Women are advised that there is little that they can do to prevent breast cancer and that early detection with screening mammograms is their best protection.

A widely shown ad informs women that "a mammogram is the best way to make sure you stay well and healthy for your whanau."

If we step back for a moment it becomes apparent that there is much more that can be done to stay well and healthy than simply having a mammogram. Some of these measures may also specifically reduce the risk of breast cancer.

More young women are smoking at a time when the overall incidence of smoking is declining. While the cause of breast cancer remains unclear, smoking is clearly implicated in lung cancer.

The smoke-free workplace legislation acknowledges the harmful effects of cigarettes. Why stop here? Why not a month-long campaign highlighting lung cancer? The Government could ban the import of cigarettes if it chose. It seems hard to justify spending $40 million a year on mammographic screening while not taking such a measure to deal with an equally deadly killer.

Many researchers suspect a link between pesticides, herbicides and cancer. This has been difficult to prove and is consequently dismissed by many as irrelevant. It makes sense, however, to treat chemicals carefully. We need to invest more in evaluating the safety of chemical products, plastics and electromagnetic radiation in industry, agriculture and the home.

Moderate to heavy alcohol intake has been linked to a number of cancers as well as breast cancer. Reducing alcohol intake would be a sensible precaution.

Diet is one of the most important lifestyle factors and has been estimated to account for up to 80 per cent of cancers of the colon, breast and prostate. More women (4324 a year) die from ischaemic heart disease and strokes than from cancer.

We know that smoking, obesity and inactivity play a major role in these conditions. If women are concerned enough about their health to endure the discomfort and anxiety associated with mammograms then, rationally, that effort should include initiatives to lose weight, stop smoking, exercise regularly and eat healthily. There is encouraging evidence that weight loss and reduced alcohol consumption may specifically reduce breast cancer risk.

It is misleading to let a woman who is overweight and a heavy smoker believe that simply having a mammogram is the most important step she can take to stay well.

Women overestimate what mammograms can achieve and are not aware of the limitations and associated risks. These unrealistic expectations can result in a sense of betrayal when breast cancer develops despite regular mammograms, sometimes over many years.

While many medical investigations require some type of informed consent, women attending for screening mammograms are seldom provided with objective information on the risks and benefits.

Diagnostic tests are used to assess a problem such as a lump that has been found and, in this setting, a mammogram may be very helpful. Screening mammography, by contrast, involves x-raying an entire healthy population with no symptoms with the aim of detecting cancers before they are big enough to feel.

If you are one of the 10 per cent of women destined to get breast cancer then a screening mammogram may detect it at an early stage where optimal treatment may reduce your risk of dying. That makes you a winner. If, however, you are one of the 90 per cent who is never going to get breast cancer, then screening will involve unnecessary x-rays for more than 25 years of your life.

Along the way there is a reasonable chance that you will end up having extra tests to investigate changes that are not cancerous and this may even involve surgery.

Unfortunately we have no crystal ball to tell which group you belong to as the majority of women with breast cancer have no identifiable risk factors.

The benefit of screening mammography comes from improved survival associated with early treatment. Advocates claim a 45 per cent reduction in the risk of dying from breast cancer in the screened population aged 65 to 69, a 30 per cent reduction for women aged 50 to 65 and a 20 per cent reduction for women 45 to 49.

If this is correct, an average 30 per cent reduction in mortality means that more than 400 out of the 600 deaths recorded annually will still occur despite optimal screening.

Most information on screening states categorically that trials have proved that it saves lives. Many would be surprised to learn that there is some controversy regarding the validity of these results.

New Zealand has never conducted a trial to test the efficacy of screening in our environment and we base our decisions on overseas results. The original trials were conducted more than 20 years ago and were poorly designed by modern standards. They have been subject to various reviews and, while enthusiasts claim conclusive evidence of benefit, one should be aware that the experts do not agree on how many lives may be saved.

It is important to realise that mammograms do not detect all cancers. Some 10 to 15 per cent of breast cancers will not show up on a mammogram and in women 40 to 50 years of age with dense breast tissue, this miss rate may be as high as 25 per cent. These are called false negative results.

Some cancers will develop in the time between screening mammograms. Some women are lulled into a false sense of security precisely because they may have had a normal mammogram in the last few months.

The use of young celebrities to promote breast cancer awareness campaigns can create the misleading impression that women in their 20s and 30s should be having screening mammograms. While there is heated debate about the benefits for women aged between 40 and 49, not even the most avid enthusiasts recommend routine screening in average-risk women younger than 40. As a breast surgeon I witness the tragic consequences of breast cancer on a daily basis. No effort should be spared to reduce the impact of this disease. But women are entitled to balanced information before proceeding with screening mammography. It is patronising to assume that this might be seen to cause confusion and discourage participation.

The fight against breast cancer cannot be won in isolation, nor by simply extending mammographic screening. If we are to rise to the challenge presented by current disease statistics, then we need to direct our energies and resources to risk reduction and primary prevention of all degenerative and malignant disease.

These initiatives will almost certainly require a radical and unpopular shift in how we manage industry, our environment and personal lifestyles.

There is much that can be done and no better time to start than the present.

* Trevor Smith is a breast surgeon at the Ascot Hospital in Auckland