A New Paradigm in Medicine and Health Care: 1. Current Paradigm (c)

[Dr Alain L Fymat]

A New Paradigm in Medicine and Health Care: 1. Current Paradigm (c)

 

In Part 1(b) in this series, I chose as a second example of the current paradigm of population medicine, the case of the Prostate Specific Antigen (PSA) Blood Test. I argued that:

 

(1) PSA is not a unique indicator of prostate cancer, but may also detect prostatitis (prostate inflammation) or benign prostatic hyperplasia (BPH, prostate anomalous growth).

 

(2) The “guidelines” issued by the several professional and governmental organizations: The United States Preventive Services Task Force (USPSTF, 2012), the U.S. Food and Drug Administration (FDA), the United Kingdom's National Health Service (NHS, 2005), and others) are confusing and even mutually contradictory.

 

(3) Clinical practice guidelines for prostate cancer screening vary and are controversial due to uncertainty as to whether the benefits of screening ultimately outweigh the associated risks.

 

(4) The test may result in over-diagnosis and over-treatment, involves risks of treatment complications, and alone costs the nation $ 3 billion/year.

 

(5) I then posited whether it would not be advisable to forego the test altogether and reserve it solely to individual patients depending on their characteristics and on their doctors' advice.

 

Whereas much more could be said about the PSA blood test, I would now like to proceed to my third example of mammography.

 

Third Example: Mammography

 

Mammography for breast cancer screening for women parallels the PSA test in men. This imaging test uses low-energy X-radiation to examine the human (female but also male) breast. It is used both as a screening and a diagnostic test.

The goal of any screening procedure is to examine a large population of patients to find that small number most likely to have a serious condition. These patients are then referred for further, usually more invasive, testing. Thus a screening exam is not intended to be definitive, rather to have sufficient sensitivity to detect a useful proportion of cancers. The cost of higher sensitivity is a larger number of results that would be regarded as suspicious in patients without disease. In mammography, the goal is the early detection of breast cancer through the detection of characteristic masses and/or micro-calcifications. Its use as a screening tool for the detection of early breast cancer in otherwise healthy women without symptoms is controversial.

Like all X-rays, mammograms use doses of ionizing radiation (lower than those employed in bone radiography) to create images that are subsequently analyzed for any abnormal findings. Adjunct procedures to mammography are:

• Ultrasound: For further evaluation of masses, including palpable masses not seen on mammograms;

• Ductography (not generally used): For further evaluation of questionable findings as well as for screening pre-surgical evaluation in patients with known breat cancer to detect any additional lesions that might change the surgical approach, for instance from breast-conserving lumpectomy to mastectomy;

• Magnetic resonance mammography: For greater spatial resolution of mammographic tissue imaging;

• Positron emission mammography; and

• New procedures, including breast tomosynthesis.

Currently recommended guidelines for having mammography screening tests for the average woman are:

• U.S. Preventive Services Task Force (2009): Screening of women aged between 40 and 49 should not be routine but based on individual's risk factors and values (because the benefits of screenings do not outweigh the risks). Every two years between the ages of 50 and 74;

• American Cancer Society, American College of Radiology, American Congress of Obstetricians and Gynecologists: Annually beginning at age 40;

• National Cancer Institute: Every one to two years for women ages 40 to 49;

• American College of Physicians: Individualized screening plans as opposed to wholesale biannual screening of women aged 40 to 49;

• Canadian Task Force on Preventive Health Care (2012): Every 2–3 years between the ages of 50 and 69. It found that for women aged 50–69, screening 720 women once every 2–3 years for 11 years would prevent 1 death from breast cancer. For women age 40-49, 2100 women would need to be screened at the same frequency and period to prevent 1 death from breast cancer; and

• European Cancer Observatory (2011): Every 2–3 years between the ages of 50 and 69.

The reports from the above task forces note that the risks of more frequent mammograms include a small but significant increase in breast cancer induced by radiation, a risk that is greater for younger women.

On the other hand, the Cochrane Collaboration (2011) analysis of screening concluded further concluded that: “Mammograms reduce mortality from breast cancer by an absolute amount of 0.05% or a relative amount of 15%, but also result in unnecessary surgery and anxiety such that it is not clear whether mammography screening does more good than harm... and that universal screening may not be reasonable”. It also states that “the best quality evidence does not demonstrate a reduction in mortality generally or a reduction in mortality from all types of cancer from screening mammography”.

In addition, the Nordic Cochrane Collection (2012) states that “advances in diagnosis and treatment make mammography screening no longer effective today in decreasing deaths in breast cancer, and therefore no longer recommend routine screening for healthy women at any age as the risks might outweigh the benefits... and warns of misleading information on the internet”. Further, their analysis showed that “one in 2,000 women will have her life prolonged by 10 years of screening, however, another 10 healthy women will undergo unnecessary breast cancer treatment. Additionally, 200 women will suffer from significant psychological stress due to false positive results”.

Repeated mammography starting at age 50 saves about 1.8 lives over 15 years for every 1,000 women screened.This result must be gauged against the negatives of errors in diagnosis, over-treatment and radiation exposure. Also, Dr. Newman points out that screening mammography does not reduce death overall, but causes significant harm by inflicting cancer scare and unnecessary surgical interventions.

About 7% (more realistically, 10%-15%) of women screened with mammography will be called back (with great distress) for a diagnostic session. However, most of these recalls will result in “false positive” results. For 1,000 recalls, about 60 will have benign growths and 10 will be referred for a biopsy (of which about 3.5 will have a cancer of which about 2 will be a low stage cancer that will be essentially cured after treatment, and 6.5 will not).

Mammography may also produce “false negatives” (not seeing the cancer), usually around 10%–30%, due to (a) observer error, (b) cancer hidden by other dense tissue in the breast, and (c) cancer overlapping normal tissues. Furthermore, one form of breast cancer, lobular cancer, has a growth pattern that produces shadows on the mammogram which are indistinguishable from normal breast tissue.A meta-analysis review of programs in countries with organized screening found 52% over-diagnosis.

Women whose breast cancer was detected by screening mammography before the appearance of a lump or other symptoms commonly assume that the mammogram "saved their lives". In practice, the vast majority of these women received no practical benefit from the mammogram. There are four categories of cancers found by mammography:

• Cancers that are so easily treated that a later detection would have produced the same total cure (that is, the woman would have lived even without mammography);

• Cancers so aggressive that even "early" detection is too late (the woman dies despite detection by mammography);

• Cancers that would have receded on their own or are so slow-growing that the woman would die of other causes before the cancer produces symptoms (mammography results in over-diagnosis and over-treatment); and

• The small number of breast cancers that are detected by screening mammography and whose treatment outcome improves as a result of earlier detection.

Clinical trial data suggests that 1 woman per 1,000 healthy women screened over 10 years falls into this category. Screening mammography produces no benefit to any of the remaining 87% to 97% of women.

In summary: The guidelines for screening mammography advocated by the several professional associations or/and governmental organizations are conflicting and even confusing. Would it not be helpful for patients if these entities were to agree to a uniform set of guidelines (even though these would still be “guidelines”)? Further, because mass screening as a tool for the detection of early breast cancer in otherwise healthy women without symptoms is controversial, shouldn't this screening be conducted on an individual basis and only in case of significant risk? Still further, since the radiation sensitivity of the breast in women under age 35 is possibly greater than in older women, should it not be generally imperative that these women be screened only if there is a significant risk of cancer (such as, BrCa positive, very positive family history, palpable mass) and even in these circumstances to employ ultrasound or magnetic resonance for imaging? Also, and likewise, should screening of women aged between 40 and 49 not be routine but based on individual's risk factors and values (because the benefits of screenings do not outweigh the risks)? Additionally, beyond age 50, should screening not be conducted systematically and only infrequently at appropriate time intervals to be defined? Lastly, based on the important Cochrane Collaboration and the Nordic Cochrane Collection, should not routine screening be discouraged for healthy women of any age as the risks might outweigh the benefits? The above provides more evidence that population medicine (in this case, mass screening) disregards individual variability and promotes considerably more unnecessary medical testing and procedures.