The bare statistics seem frightening, and have been used by doctors to press-gang women into being tested for breast cancer as early as possible. In the US, screening for breast cancer has become a huge money-making industry - but what if the figures are wrong? What if medicine is seriously overdiagnosing as cancer a condition that is essentially harmless?
During the last 10 years, breast screening has been called into question largely over basic questions of accuracy. In fact, a growing number of experts believe that the advent of breast-cancer screening has created a problem where none may actually exist, labelling and treating many conditions as cancer which aren't serious or life-threatening.
The astonishing fact is that fully half of all cases of so-called "breast cancer" might not be cancer at all, but a harmless abnormality that will never progress to cancer. In some 40,000 cases in the US, women could be being wrongly treated for cancer.
What is breast cancer?
Breast cancer is a growth of undifferentiated cells in the breast area usually causing a lumpy tumor. However, the overwhelming majority - some 80 per cent of breast tumors - is not cancerous. The first stage of one type of cancer is believed to be when a milk duct or lobule is invaded by microscopic calcifications. Most of these are so tiny that they cannot be seen or felt, and are only detectable on a mammogram. The calcifications are believed to be the precursors of cancer, but they are not in themselves cancerous. Nevertheless, they are somewhat misleadingly called "carcinomas in situ" (CIS), which means "cancers in place." Doctors refer to the calcifications that occur in lobules as "LCIS" and the ones in ducts as "DCIS," which is much the more common diagnosis of the two.
Before mammography, DCIS was virtually unknown, but it now accounts for up to 50 per cent of breast cancer diagnoses. The conventional view is that identifying DCIS is a good thing as it picks up cancer in the early stages, thus enabling treatment to prevent the cancer from developing.
At least, this is the message given to patients, but some experts are beginning to question the whole philosophy.
"Doctors should make it clear that DCIS is not cancer; it is only a possible precancer," says Dr Eric Wiener, head of breast oncology at the Dana-Farber Cancer Institute in Boston, Massachusetts.
The plain fact is that most DCIS does not become cancerous - a finding made by pathologists doing autopsies on women who had died of something else. Post mortems show that many women may have DCIS harmlessly in their breasts for years; it is only when DCIS spreads out beyond the duct (it is no longer "in situ") that cancer might begin. The problem is that doctors don't know what types of DCIS break out and become carcinogenic, or even how often DCIS turns into cancer. If left untreated, some DCIS will break out and cancer will develop. But these cases are by far the minority. Most DCIS causes no problems at all. Nevertheless, doctors almost universally recommend treatment, arguing that it is always "better to be safe than sorry."
Cancer statistician Dr Donald Berry, head of biostatistics at the M.D. Anderson Cancer Center in Houston, Texas, labels this "knee-jerk" medicine.
In the hard-hitting article "Epidemiology versus scare-mongering," UK cancer expert Professor Michael Baum attacked health professionals for scaring women into unnecessary treatment. Baum has 30 years of experience as a breast-cancer surgeon at the Royal Free Hospital and, in his view, if left untreated, as many as 80 per cent of all DCIS cases will never become cancerous (Breast J, 2000; 6: 331-4).
This is backed up by American research aimed at quantifying the true risks of DCIS. Cancer statistician Dr Virginia Ernster, at the University of California at San Francisco, looked back over the death statistics of about 7000 women who had been diagnosed with DCIS, both before and after screening had become widespread. She found that, before the advent of screening, only 3.4 per cent of the women died of breast cancer, with the figure dropping to 1.8 per cent after its introduction. In either case, the "risk of death was low," commented Dr Ernster (Arch Intern Med, 2000; 160: 953-8).
The usual treatment for DCIS is a combination of the three standard anticancer weapons - surgery, chemotherapy and radiation, often disparagingly dubbed "cut, poison and burn" by their detractors. Although DCIS is not breast cancer, its treatment regime is similar to what is given for the full-blown disease. Doctors will either recommend surgery to remove the so-called diseased part (lumpectomy) or even to remove the whole breast (mastectomy), followed by chemotherapy and/or radiation (Am J Nurs, 2001; 101: 11). Nevertheless, a recent review of the evidence by cancer expert Maryann Napoli came to a stark and dramatic conclusion: there is no benefit whatsoever from any conventional treatment for DCIS. Napoli, who runs the Center for Medical Consumers in New York, surveyed the US mortality rates in women diagnosed with DCIS, and found that just 1 per cent of them died from breast cancer - whether their DCIS was treated or not (Am J Nurs, 2001; 101: 11).
"Seventy per cent of women with a DCIS diagnosis are being overtreated and getting all the downsides of treatment - surgical scars, side-effects of surgery, radiation and tamoxifen," says Professor Susan Love, cancer expert at the University of California at Los Angeles.
All women need to be aware that what their doctor tells them might not be the whole story. When it comes to their health, women need to keep asking, "What is the research on this treatment? What are the other options? Where can I find more information?"
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