Mammography

“There are risks and costs to action. But they are far less than the long range risks of comfortable inaction.”

John F. Kennedy

Almost all situations in life involve a risk to benefit ratio calculation. In order to make that calculation we need to know the facts. In medicine that is made even more difficult, because the facts almost always come from research. Research is often difficult to understand, can be designed to prove a pre-determined outcome and is prone to statistical manipulation.

That’s one of the reasons I now resort to common sense a lot, and my first guideline is always “nature does it best”. My second guideline is “prevention is better than cure”. Read this article, but remember that adopting a healthy lifestyle, including eating to prevent yeast, is the most important aspect to the prevention of breast cancer. Let’s have a look at the facts as they currently stand in the great mammogram debate and see how the alternative known as thermography stands up to scrutiny.

Mammography

1. Mammography is performed by compressing the breasts between two X-Ray plates; a radiologist’s interpretation of changes seen on the X-Ray is then required. X-ray images appear in gradations of black, gray, and white, depending on the density of the tissue. Bone is especially dense and appears white on an x-ray, while fat is much less dense and appears dark gray. Cancerous tumors and some other noncancerous abnormalities appear as a lighter shade of gray. However, normal dense breast tissue may also appear light gray on a mammogram. Women under the age of 50 have denser breasts, making mammograms difficult to interpret.

2. False positive is a term used when a mammogram suggests there is breast cancer when there is not. The false positive rate ranges from 2.6% to 15.9% (Elmore et al. 2002). False positives usually result in additional diagnostic tests, which can include an additional x-ray examination, or a biopsy. Recent data from the University of Washington and Harvard University revealed that over a period of a single decade, one out of every two women will have a false positive result as the result of mammography. Of those, nearly 20 percent will undergo an unnecessary breast biopsy. (Fletcher SW, NEJM)

3. False negatives – A portion of the population’s mammograms are misread as false negatives. A false negative mammogram occurs when the mammogram is read as “normal” or “negative”, although a malignancy is present. Studies put the false negative rate at about 30%.

4. At present, the current orthodox medical consensus is that the benefits of screening women over 50 years of age with mammograms outweighs the associated risks due to radiation exposure. However, there appears to be no significant benefit for women under the age of 40, and there may be harm for women under 30 due to the danger of cancer developing after exposure to radiation. Therefore, the main area of controversy concerns women between the ages of 40 and 49.

5. The controversy really became hot with the Cochrane Database review of all the research. This is what they found: “For every 2000 women invited for screening throughout 10 years, one will have her life prolonged. In addition, 10 healthy women, who would not have been diagnosed if there had not been screening, will be diagnosed as breast cancer patients and will be treated unnecessarily. It is thus not clear whether screening does more good than harm.”

The Cochrane analysis found that, “Claims for the benefit of screening mammography in reducing breast cancer mortality are based on eight international controlled trials involving about 500,000 women. However, recent meta-analysis of these trials revealed that only two, based on 66,000 postmenopausal women, were adequately randomized to allow statistically valid conclusions.”

Based on these two trials they concluded that, “there is no reliable evidence that screening decreases breast cancer mortality — not even a tendency towards an effect.”

6. A review paper in the January 2012 edition of Cancer Causes Control stated, “Recent observational studies of breast cancer mortality have failed to find an effect of screening. In contrast, screening leads to serious harms in healthy women through over diagnosis with subsequent over-treatment and false-positive mammograms. We suggest that the rationale for breast screening be urgently reassessed by policy-makers. The observed decline in breast cancer mortality in many countries seems to be caused by improved adjuvant therapy and breast cancer awareness, not screening. We also believe it is more important to reduce the incidence of cancer than to detect it early.”

7. Where do the risks come from? Firstly, it’s radiation. In a paper published in International Journal of Health Services 2001, Dr Samuel Epstein writes, “Premenopausal women undergoing annual screening over a ten-year period are exposed to a total of about 10 rads for each breast. As emphasized some three decades ago, the premenopausal breast is highly sensitive to radiation, each rad of exposure increasing breast cancer risk by 1 percent, resulting in a cumulative 10 percent increased risk over ten years of premenopausal screening, usually from ages 40 to 50.”

Secondly it’s the trauma from compression. Epstein writes, “As early as 1928, physicians were warned to handle cancerous breasts with care for fear of accidentally disseminating cells and spreading cancer. Nevertheless, mammography entails tight and often painful compression of the breast, particularly in premenopausal women. This may lead to distant and lethal spread of malignant cells by rupturing small blood vessels in or around small, as yet undetected breast cancers.”

8. Then, even when a cancer is detected by mammography, is it too late to make a difference? “The overwhelming majority of breast cancers are unaffected by early detection, either because they are aggressive or slow growing.” Napoli MJ, Natl. Cancer Inst. Monogr. 1997.

10. Early detection may not be nearly as important as other aspects of the cancer. “There is supportive evidence that the major variable predicting survival is biological determinism — a combination of the virulence of the individual tumor plus the host’s immune response, rather than just early detection.” Lerner BH. Am. J. Public Health 1999.

11. Then we have to take into account statistical magic. Epstein writes, “Even assuming that high quality screening of a population of women between the ages of 50 and 69 would reduce breast cancer mortality by up to 25 percent, yielding a reduced relative risk of 0.75, the chances of any individual woman benefiting are remote. For women in this age group, about 4 percent are likely to develop breast cancer annually, about one in four of whom, or 1 percent overall, will die from this disease. Thus, the 0.75 relative risk applies to this 1 percent, so 99.75 percent of the women screened are unlikely to benefit.” He concludes by saying what all of us who read this newsletter know: “Besides lifestyle and reproductive risk factors, emphasis should be directed to the massive over prescription of carcinogenic hormonal drugs and the avoidable and involuntary exposures to petrochemical and radio nuclear carcinogens in the totality of the environment.” Yes, he forgot microbiological (fungi), but we’ll forgive him because he’s on the right track!

To really understand the secrets of the statistical magicians, we have to understand the difference between relative and absolute risk. We are often quoted relative risk to make decisions on, but it’s meaningless. We need the absolute risk. Studies have shown that if doctors are asked if they would prescribe a drug that reduces the risk of a heart attack by 20% (relative risk), twice as many say they would prescribe it compared to when they are asked if they would prescribe the drug if it reduces the risk from 7.8 to 6.3% (absolute risk). It’s the same drug, same benefit, just expressed a different way.

The Swedish mammography trials showed that the death rate from breast cancer for women having mammograms over 15 years was 0.4%. In the control group, the death rate over 15 years was 0.5% (a 20% relative reduction).

Let’s look at the numbers another way. How much does mammography extend life? It has been calculated that the average woman in her 40s or 50s will gain three extra days of life. For women in their 60s, it is eight extra days.

Alternatively, we can calculate the number of procedures needed to save one life. This way, if 1000 50-year-old women do NOT have mammograms, 13 will die of breast cancer before they reach the age of 75. If the 1000 woman do have regular mammograms, 10 will still die of breast cancer. This equates to a total of 3,333 individual mammograms to prevent one death.

Now, let’s look at thermography.

1. Thermography uses infrared technology to measure temperature changes in the breast. It’s painless, non-invasive and there is no radiation. It lost favor 20 years ago, but refinements have seen an increase in popularity and research recently. The cameras can detect minute temperature variations related to blood flow and can demonstrate abnormal blood flow patterns associated with cancer.

2. This is particularly useful for women under the age of 40, because mammograms are definitely not indicated in this age group. Given that breast cancer is the leading cause of death in women between the ages of 40 and 44, that they aren’t usually palpable until they are greater than 1cm, that by then 25% have already metastasized and that most breast cancers take 15 years from beginning to the end, thermographic screening of women starting in their 20’s makes good sense.

3. More than 800 research papers (mainly from Canada and France) have been published, and there is a research database of over 300,000 women.

4. Modern infrared scanners have a thermal sensitivity of 0.05 degrees Centigrade. Cancer cells can’t regulate their temperature, so when the breast is cooled with small fans in a room kept at 68 degrees Fahrenheit, blood vessels of normal tissue constrict to conserve heat while tumor tissue remains hot.

5. Thermograms are graded 1-5. Th1 and Th2 are normal, Th3 is moderately abnormal, and Th4 and Th5 are severely abnormal. One recent study documented that women with Th1 and Th2 scores can be reassured with a 99% level of confidence that they do not have breast cancer. (Parisky YR, Efficacy of Computerized Infrared Imaging Analysis to Evaluate Mammographically Suspicious Lesions. American Journal of Roentgenology, January 2003)

6. More than 95% of breast cancers can be identified, and that this is done with 90 percent accuracy. In women under the age of 50, who have the most devastating loss of life from breast cancer, this is better than any other imaging modality.

7. The FDA approved breast thermography for breast cancer risk assessment in 1982.

I’m not going to advise anyone on what to do. I’m not even going to say what I’d do, because I’m not a woman, and any risk/benefit calculation has so many individual components that it’s not possible to do for anyone else. The take home message is that making a choice is difficult. I suggest using common sense; remember that nature does it best and don’t get stuck with inaction.