Think twice about these tests
This is an area where WDDTY is more likely to be right, simply because there is a reasonable consensus that screening leads to overdiagnosis and false positives. However, WDDTY’s advice is based on prejudice and dogma. It is less complete and less well argued than the numerous evidence-based discussions of the pros and cons of various tests.
Our advice on avoiding unnecessary tests is this: read Dr. Margaret McCartney’s The Patient Paradox. This will help you to understand false positives and false negatives, and to ask intelligent and informed questions that will lead you to make a pragmatic choice over a particular test, rather than hysterical anti-medicine rejection of all tests however appropriate.
51 The PSA (prostatespecific antigen) blood test for prostate cancer
It produces false negatives a third of the time and has overdiagnosed more than one million men since its introduction in 1987.29 Unless you have an aggressive cancer, consider watchful waiting. Ditch statin drugs, which increase your risk of this cancer by one-and-a-half times, and reduce carbs, avoid red meat and eat a Mediterranean diet.
PSA is a marker, it is useful in monitoring progression as part of “watchful waiting” (the standard of care for indolent prostate cancers) but its use as a screening test is controversial, not least because the “normal” level of PSA varies widely. From the Wall Street Journal:
Richard Ablin, a professor of pathology at University of Arizona College of Medicine, discovered the prostate-specific antigen in 1970, and for nearly as long, he has argued that it should not be used for routine screening.
So the fact that PSA screening is problematic is not only not something “doctors don’t tell you”, it’s something that the inventor of the test itself has been saying for decades, and which medical journals are confirming.
PSA screening has been discouraged in the UK since the 1990s.
WDDTY can never resist a dig at statins (we’ll review that later), or an opportunity to plug the mediterranean diet (presumably in a modified version that does not include pasta, breads or tomatoes, since these are all fingered as causing problems within this article as well as elsewhere).
52 Routine mammograms (unless cancer is suspected)
This blunderbuss approach, which uses X-rays to detect breast cancer, doesn’t see cancer at its earliest stages and fails to pick up aggressive tumours. For every woman whose cancer is correctly detected, 10 healthy women will go through unnecessary worry, further testing and even treatment before doctors realize they’ve been misled by a false-positive. Consider thermography instead.
So close! This was almost a correct piece of advice, and then they went and ruined it by promoting a quack diagnostic technique instead.
Breast thermography is, to put it bluntly, useless as a diagnostic tool. It’s dissected here by David Gorski, a surgical oncologist specialising in breast cancer. To quote the American Cancer Society:
Thermography has been around for many years, but studies have shown that it’s not an effective screening tool for finding breast cancer early. Although it has been promoted as helping detect breast cancer early, a 2012 research review found that thermography detected only a quarter of the breast cancers found by mammography. Thermography should not be used as a substitute for mammograms.
Oh, and mammograms do detect cancer, just not perfectly. As with any area of medicine, breast cancer staging and screening is a work in progress. There is a debate about what to do with DCIS, for example. There is certainly a debate about routine mammography and the ages at which it should be considered. Above all, our understanding of the nature of indolent disease is developing rapidly. It seems likely that as the population ages many more people are likely to die with cancer than die of cancer.
53 Blood pressure readings
Many factors can distort a BP reading by as much as 5 mmHg: acute exposure to cold, recent alcohol intake, incorrect arm position, an incorrect cuff size—and even the presence of the doctor, now so common that it’s called ‘white-coat’ hypertension. Blood pressure falls at night, and night-time blood pressure is considered the most accurate predictor of heart attack.30 Consider 24-hour blood-pressure monitoring, not the old-fashioned cuff.
Reference 30: Lancet. 2007 Oct 6;370(9594):1219-29. Prognostic accuracy of day versus night ambulatory blood pressure: a cohort study. Boggia J et. al.
Why don’t doctors tell you this? Oh, they do. A single high reading in the doctor’s surgery is never the trigger for intervention unless it’s very high. Normal range is 120/80 to 140/90, so the uncertainty of 5 mmHg is clinically insignificant – if your pressure is 200/100 this is not going to be down to the white coat effect.
Compare and contrast WDDTY’s advice with that from the National Institutes for Health.
54 Routine smear tests
Many doctors still offer women an annual smear test for cervical cancer—even though they’ve been told the test can do more harm than good. The test throws up many false positives—incorrectly ‘seeing’ abnormal tissue that triggers a series of further and more invasive tests, plus needless worry. Even the advises a smear test once every three for those aged over and once every five years for those between 30 and 65.31
Routine smear tests are a curate’s egg. In women at high risk, they are likely to be warranted. In women at low risk, not so much. If your GP is not up on the current state of knowledge (and they should be), ask for a referral to a specialist gynaecological clinic.
The take-home message that must be reinforced here is not that screening is evil, but that a borderline positive smear is not a cause for worry, it is a prompt for further investigation only.
55 Routine dental X-rays
Your dentist keeps telling you it’s safer than an airplane flight, but dental X-rays could triple the risk of meningioma, a kind of brain tumour. Children who have a Panorex or full-mouth X-ray before the age of 10 run the greatest risk, and even bitewing X-rays increase risk. Regular exposure may also cause heart disease. Annual checkups should be urgently reconsidered, say Yale University researchers.32
Reference 32: Cancer, 2012; 118: 4530–7 Dental x-rays and risk of meningioma. Claus EB, Calvocoressi L, Bondy ML, Schildkraut JM, Wiemels JL, Wrensch M.
Actually we agree that you should avoid unnecessary X-rays, because unlike WDDTY we understand the difference between ionising and non-ionising radiation. X-rays are ionising radiation.
But good dentists don’t do routine X-rays. They use them to diagnose and guide treatment. If your dentist recommends routine X-rays then consider changing your dentist.
If you want an example of gratuitous exposure to unnecessary X-rays, look to your local chiropractor.
56 CT (computed tomography) scans
This whole-body, three dimensional imaging system is one of the most sensitive early-warning detectors of cancer, internal bleeding, heart problems, stroke and neurological disorders, but the standard course of two or three CT scans is equivalent to the radiation levels of Hiroshima or Nagasaki atomic bombs;33 just one scan is equivalent to around 500 standard chest X-rays, reckons the Royal College of Physicians of Edinburgh. Children who are scanned run a far higher risk of developing cancer.34 Ask for any other kind of imaging exam first.
Reference 33: N Engl J Med, 2007; 357: 2277–84 Computed Tomography — An Increasing Source of Radiation Exposure David J. Brenner, Ph.D., D.Sc., and Eric J. Hall, D.Phil., D.Sc
Reference 34: Radiat Res, 2010; 174: 753–62 Thyroid cancer risk 40+ years after irradiation for an enlarged thymus: an update of the Hempelmann cohort. Adams MJ, et. al.
This is a rehash of a story in the December 2013 issue, “CT scans increase children’s cancer risk“. The second reference is puzzling as it refers to patients who had radiotherapy, not CT scans. The evidence for increased risk of cancers in children following CT scans is epidemiologically sound and does not rely on making inferences from unrelated research.
CT scans are used to rule out potentially life-threatening conditions, especially in children. Brain haemorrhage, for example. The sources are unanimous in supporting their diagnostic use and the fact that the benefits outweigh the risks, but equally unanimous in urging caution and ruling out other diagnostic tests first.
It should be pointed out that radiation increases risk, but does not inevitably produce cancer. Tsutomu YamaguchiW was exposed to radiation equivalent to the Hiroshima and Nagasaki bombs, having been caught in not one but both blasts. He died in 2010 aged 93. The Wikipedia article on hibakushaW (survivors of the atomic bombs) is interesting; the fact that the memorials are still being updated annually does indicate that being exposed to radiation is not a death sentence, however undesirable it might be.
The take-away message here is that it’s fine to challenge the diagnostic necessity of any test, but don’t rule out scans that reveal potentially fatal conditions just because of fear of some uncertain future consequence.
57 Routine prenatal ultrasound
The prenatal ‘miracle’, which uses high-frequency pulsed sound waves to image the fetus in the womb, gets it wrong so often that up to one in 23 women told by doctors they’ve miscarried may end up terminating a pregnancy. Scans see’ a miscarriage the pregnancy is viable, say researchers London and Belgium.35 Reserve this when something really wrong, and consider waiting before ‘completing’ termination if the test concludes you’ve miscarried.
Reference 35: Ultrasound Obstet Gynecol, 2011; 38: 503–9 Gestational sac and embryonic growth are not useful as criteria to define miscarriage: a multicenter observational study. Abdallah Y, et. al.
A second bite at the cherry for ultrasound (should we dock one from the tally of 100 things and make it 99 things?). Does the source support WDDTY’s conclusion? Only partly:
There is an overlap in MSD growth rates between viable and non-viable IPUV. No cut-off exists for MSD growth below which a viable pregnancy could be safely excluded. A cut-off value for CRL growth of 0.2 mm/day was always associated with miscarriage. These data suggest that criteria to diagnose miscarriage based on growth in MSD and CRL are potentially unsafe. However, finding an empty gestational sac on two scans more than 7 days apart is highly likely to indicate miscarriage, irrespective of growth.
In other words, there is a level at which ultrasound can detect a definitely non-viable pregnancy, but the margins are more blurred than was thought. This is in first trimester pregnancies, where only a few generations ago many women would not even know they were pregnant. Spontaneous abortionW is common in the early stages, often before the woman is even aware that she’s pregnant.
The source absolutely does not support a blanket rejection of obstetric ultrasonographyW, or even of early ultrasound where bleeding is present. However, the mandatory use of ultrasound introduced by anti-abortionists in some US states is unquestionably abusive and morally repugnant.
58 Peripheral bone densitometry
It’s the most commonly diagnostic tool for osteoporosis, and it measures usually the hip and spine, but bone mineral density (BMD) is not uniform throughout the skeleton. Although the WHO criteria for a healthy BMD apply only to the hip and spine, a wide range of ‘normal’ BMDs elsewhere in the body may be misdiagnosed as abnormal by these criteria. Diagnosing osteoporosis is still not an exact science, say researchers; you have a strong chance of being misclassified, especially when the test is done in those under 65.36
Reference 36: BMJ, 2000; 321: 396–8 The increasing use of peripheral bone densitometry (Editorial)
Differential diagnosis of osteoporosisW versus osteopeniaW is indeed a grey area, but it’s a distinction without a difference as both indicate a loss of bone density. DEXA scans can be perofrmed on central or peripheral bones, peripheral scans are easier and the machinery is smaller (and often portable).
Needless to say the BMJ article does not undermine the use of bone densitometry, but does question the use of a pragmatic epidemiological definition of osteoporosis, as the threshold for intervention. In other words, it may be valid to treat low-end osteoporosis as osteopenia – essentially using calcium and vitamin D as a first line of treatment before launching right in with bisphosphonatesW. This is what any good doctor would do anyway. But how will the doctor make the diagnostic call without a DEXA scan? Would you prefer a core DEXA, involving a trip to the radiology department of your nearest big hospital and a longer procedure with greater X-ray exposure, or a possibly clinic-based scan that will give a less accurate but probably still clinically useful answer?
As usual, WDDTY takes an absolutist stance that doesn’t help.
In a biopsy, a small bit of tissue is removed under local anaesthetic to diagnose a serious illness like cancer. Besides infection, puncturing nearby organs, and causing tears and bleeding, the greatest danger is that biopsies can inadvertently ‘seed’ or spread cancer. With breast biopsies, the risk of recurrent cancer from a ‘needle metastasis’ is about one in 15.37 Request PET (positron emission tomography) or MRI (magnetic resonance imaging) instead.
Reference 37: Acta Radiol Suppl. 2001 Dec;42(424):1-22. Aspects in mammographic screening. Detection, prediction, recurrence and prognosis. Thurfjell MG.
The relevant section of the abstract is:
Local recurrences in 303 nonpalpable breast cancers with preoperative localizations and breast conservation therapy were evaluated for needle-caused implant metastasis. A total of 214 percutaneous biopsies were performed. There were 33 local recurrences. Needle-caused seeding or implantation as based on the location of the recurrence in comparison to the needle path in the mammograms was suspected in 3/44 (7%) invasive cancers without radiotherapy.
This absolutely does not support the idea of rejecting biopsy. These instances of needle-caused seeding are primarily in women who had breast-conserving surgery (“lumpectomy”) for active cancers, and note that it’s more likely to happen when women opt not to have radiotherapy. In the absence of cancer, there are no seed cells.
The overall thrust of the article is actually a vindication of diagnostic mammography:
Screening mammograms comprising of 32 first round, 10 interval and 32 second round detected cancers and 46 normal were examined by an expert screener, a screening radiologist, a clinical radiologist and a computer-assisted diagnosis (CAD) system. The expert screener, screening radiologist, clinical radiologist and the CAD detected 44, 41, 34 and 37 cancers, respectively, while their respective specificities were 80%, 83%, 100% and 22%. Later, with CAD prompting, the screening and the clinical radiologist detected 1 and 3 additional cancers each with unchanged specificities. Screening mammograms comprising 35 first round, 12 interval and 14 second round detected cancers and 89 normal findings were examined without and with previous mammograms by experienced screeners. Without previous mammograms, the screeners detected 40.3 cancers with a specificity of 87%. With previous mammograms, 37.7 cancers were detected with a 96% specificity.
Neither PET nor MRI can accurately diagnose whether a tumour is malignant or not. If your doctors recommend a biopsy, it’s because they think you are likely to have cancer. The utility of baseline mammograms is demonstrated, as is the importance of having a properly trained clinical radiologist review the films.
As to the issue of seeding, Prof. Bill Heald CBE, pioneer of the total mesorectal excisionW procedure for colorectal cancer, is a firm advocate of lavage to minimise seeding – he routinely flushed the abdominal cavity and port sites with copious amounts of dilute antiseptic.
Discouraging people from having a truly accurate differential diagnostic pathological test to differentiate the presence, type and possibly aggression of a cancer? I’d question the medical credentials of anyone giving such advice. If indeed they had any.
60 Computed tomography (CT) angiography
The use of intravenous dye and CT technology to provide an ‘inside view’ of the coronary arteries is fast replacing the exercise stress test done in doctors’ surgeries. It’s also doubling the rate of invasive cardiac procedures, including surgery, say Stanford University School of Medicine researchers.38 Ask to have the standard gym bike or treadmill stress test instead.
Reference 38: JAMA. 2011 Nov 16;306(19):2128-36. Association of coronary CT angiography or stress testing with subsequent utilization and spending among Medicare beneficiaries. Shreibati JB, Baker LC, Hlatky MA.
WDDTY advocate an older test because it finds fewer cases. Remind me again why that would be a valid criticism? Computed tomography angiographyW is a relatively new technique. As with any CT scan, there is exposure to ionising radiation. As with any CT scan, it will only be appropriate when the risks are outweighed by benefits. Rejecting a test on ideological grounds, as WDDTY do, is foolish.