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Tuesday, December 1, 2009

Mammograms Misunderstood

The United States Preventive Services Task Force recently changed their recommendations regarding screening mammography. After a thorough review of the research, this independent panel of experts appointed by the Department of Health and Human Services concluded that most women should be tested every two years between the ages of 50 and 74, replacing previous recommendations for yearly lifelong tests starting at age 40.

The new guidelines have been met with confusion and outrage. Critics have dismissed them as a cost-cutting measure and described them as “a giant step backward.” The new recommendations have been called “deadly for women” and even “gendercide.” Although they could save billions of dollars in unnecessary testing and treatment, the financial savings are only a bonus. The new guidelines really are good for women and a review of the literature can quickly clear up the controversy.

Zero Benefit

In 2001 the benefits of screening mammography underwent serious scrutiny by the well-respected Cochrane Collaboration, an international, independent, not-for-profit research organization. They performed an objective and systematic review of the seven largest screening mammography studies ever done and examined the effects in a half million women from the United States, the United Kingdom, Canada and Sweden.

Two of the seven studies met the gold standard for research: randomized controlled trials. They followed 130,000 women for 13 years and compared women who received regular mammograms to those who did not. Researchers found that the rate of death from breast cancer, and from any other cause, was the same in both groups. When all seven studies were considered, mammograms were still not associated with a statistically significant reduction in the risk of death. Surprising as these studies are, the results are clear: screening mammography does not save lives.

False Positives

Mammograms are positive when abnormal tissue is detected. False positive tests occur when mammograms mistakenly identify cancer in normal tissue. A 2005 review of randomized controlled trials published in the Journal of the American Medical Association found that 95 percent of positive mammography results are false. A Harvard study published in the New England Journal of Medicine found that only three percent of abnormal mammography results were valid, making the frequency of failure 97 percent.

False positive results can be a grave matter. A study published in the Annals of Internal Medicine found that 47 percent of women with high-suspicion mammograms experience substantial anxiety. While most women are relieved to learn that their test results were wrong and they do not have cancer, many suffer unnecessary emotional turmoil.

Harmful Effects

Screening mammography can have other harmful effects. Women with false positive results are needlessly subjected to biopsies, lumpectomies and associated adverse effects, including pain, infection and scarring. Those with true positive results are too often treated for cancers that would have otherwise gone unnoticed. A 2009 study published in the British Medical Journal concluded that one out of every three breast cancers identified on screening mammograms is overdiagnosed and would not cause symptoms or death. The surgery, chemotherapy and radiation used to treat these tumors are always harmful. Side effects and complications can include mouth sores; fatigue; vomiting; digestive problems; skin rashes; hair loss; damage to peripheral nerves; changes in brain function affecting memory, concentration and learning; premature menopause; leukemia (cancer of the blood); and death.

Ionizing radiation from mammograms is another valid concern. It can damage genetic material in cells and cause cancerous mutations. These tests are used to find cancer, but taking too many of them can also cause cancer. This detail has been overlooked in the past because the benefits of mammograms – saving lives – were thought to outweigh the harmful effects. But for most women, screening mammography does not save lives and the risks associated with radiation can no longer be ignored. There is a direct relationship between cumulative exposure to radiation and the risk of cancer, so the more mammograms (and other procedures involving ionizing radiation like CT scans) that women receive over their lifetimes, the more likely they are to develop cancer.

Some Exceptions

Screening mammography may not reduce the risk of death for most women, but for certain women, the benefits can outweigh the dangers. Women who have the highest risk for developing breast cancer have the most to gain from screening tests. These include women with two first-degree relatives (mother, daughter, sister) or second-degree relatives (aunt, grandmother) diagnosed with breast cancer before the age of 50; women who have three first- or second-degree relatives with breast cancer diagnosed at any age; individuals with a history of chest radiation between the ages of 10 and 30; and those who have a known gene mutation linked to breast cancer. These individuals should talk to their doctor about the best screening schedule for them.

Diagnostic mammograms are another exception. Unlike screening mammography, which is performed on healthy women, diagnostic mammography is used to evaluate known breast problems. For women with lumps, tissue abnormalities, nipple discharge or a history of cancer, these tests can provide life-saving information for diagnosis and treatment.

Accurate Alternative

Thermography is a promising alternative to mammography. This infrared imaging technique is painless, non-invasive and free of radiation. It measures heat patterns on the surface of the skin related to blood flow and angiogenesis, the formation of new blood vessels. Angiogenesis is a critical step in the growth of cancer because as abnormal cells increase in number, so do their requirements for oxygen and nutrients, the food needed to fuel proliferation. To meet their expanding needs, tumors generate new blood vessels to increase blood flow, which increases skin temperature.

Because these vascular changes can be detected sooner than solid tumors, which may take years to grow large enough to block x-ray beams and be identified on mammograms, thermograms can identify signs of cancer in its earliest stages. Some experts estimate that thermography recognizes cancerous or pre-cancerous changes up to 10 years earlier than any other procedure, mammography included.

Studies have shown that thermograms are also much more accurate than mammograms. A review of 15 large-scale studies published in the International Journal of Thermal Sciences concluded that breast thermography had an average sensitivity and specificity of 90 percent. (Sensitivity is the percentage of accurate positive results and specificity is percentage of accurate negative results.) Other studies have found sensitivity as high as 98 percent and specificity as high as 94 percent. With rates of false positive and false negative results averaging only 10 percent, thermography is an accurate alternative to mammography.

The Bottom Line

Like any medical procedure, the pros and cons of mammograms must be considered carefully. Given the frequently false positive results, lack of benefit and exposure to radiation, screening mammography is not an effective tool for detecting breast cancer in the general population. For most women, preventive measures are much more beneficial: exercising regularly, maintaining an ideal weight, breastfeeding, avoiding pesticides and eating a healthy diet that includes seven or more daily servings of fruits and vegetables, especially cruciferous and dark green leafy vegetables.

REFERENCES

Elmore JG, Fletcher SW et al. Screening for breast cancer. Journal of the American Medical Association, 293(10):1245-56, 9 Mar 2005.

Fletcher SW and Elmore JG. Mammographic Screening for Breast Cancer. New England Journal of Medicine, 348(17):1672-1680, 24 Apr 2003.

G√łtzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database of Systematic Reviews 2009, Issue 4. Art. No.: CD001877. DOI: 10.1002/14651858.CD001877.pub3.

Griffey RT and Sodickson A. Cumulative radiation exposure and cancer risk estimates in emergency department patients undergoing repeat or multiple CT. American Journal of Roentgenology, 192(4):887-92, Apr 2009.

Haberman J. The present status of mammary thermography. CA: A Cancer Journal for Clinicians, 18: 314-321,1968.

Jorgensen KJ and G√łtzsche PC. Overdiagnosis in publicly organised mammography screening programmes: systematic review of incidence trends. British Medical Journal, 339:b2587, 9 July 2009.

Lerman C et al. Psychological and behavioral implications of abnormal mammograms. Annals of Internal Medicine, 114(8):657-61, 15 Apr 1991.

Nelson HD et al. Screening for breast cancer: an update for the U.S. Preventive Services Task Force. Annals of Internal Medicine, 151(10):727-37, W237-42, 17 Nov 2009.

Ng EY-K. A review of thermography as promising non-invasive detection modality for breast tumor. International Journal of Thermal Sciences, 48(5):849-859, May 2009. DOI:10.1016/j.ijthermalsci.2008.06.015.

Ng EY et al. Computerized detection of breast cancer with artificial intelligence and thermograms. Journal of Medical Engineering & Technology, 26(4):152-7, Jul-Aug 2002.

Stark A and Way S. The Screening of Well Women for the Early Detection of Breast Cancer Using Clinical Examination with Thermography and Mammography. Cancer 33:1671-1679, 1974.

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