of Health in Michigan. One-third of the units studied routinely exceeded the various standards of radiation exposure.72
The US aimed to correct this problem with the Mammography Quality Standards Act, passed in October 1992, which was to establish quality-control standards and a certification system for the more than 10,000 medical facilities that perform and interpret mammograms. These quality-control standards relate to the training and education of personnel, the equipment and the dosage used, among other criteria. Doctors would also have to have continuing education in reading mammograms and be expected to interpret an average of 40 mammograms a month.
As of October 1994, every facility performing mammograms had to obtain a certificate or provisional certificate to continue to operate legally.
However, although setting standards has undoubtedly improved some of the appalling mistakes made in the past, it may do nothing to improve the inherent imprecision of the technology itself. Even mammograms of the best quality can be misread by highly experienced radiologists. In one study carried out by Yale University, 10 seasoned radiologists, with 12 years’ experience in reading mammograms, each given the same 150 good-quality mammograms, differed in their interpretation a third of the time. In a quarter of cases they also radically disagreed over how the patients should be managed (such as whether they should have follow-up mammograms or exploratory surgery). Even among the 27 patients later definitely diagnosed as having breast cancer, the radiologists varied widely in their diagnosis. Nearly a third of cancers were wrongly categorized. One radiologist did not detect a cancer that was clearly visible, while another thought it was developing on the breast opposite the one where it actually was.73
Even if regular screening doesn’t spread or cause cancer, its dubious benefits may not be worth the pain reported by a third of women undergoing the screening.74 Helen, from Westcliff on Sea, now in her early fifties, has suffered with lumpy breasts and severe mastitis for 20 years. She’s had several routine ‘horizontal’ mammograms and a fine-needle aspiration of a cyst she found 12 years ago. Then, in 1991, she had another mammogram. ‘This time I had to stand upright and each breast was squashed vertically against the machine. The pain was excruciating. Tears welled up in my eyes and I could hardly stop myself from shrieking. The pain lasted in both breasts for three or four days before gradually subsiding,’ she says.
SCREENING FOR OVARIAN CANCER
Today, most US gynaecologists routinely screen for ovarian cancer. This widespread screening was prompted by the highly publicized death in 1989 of the actress and comedienne Gilda Radner at the age of 42 from ovarian cancer. Screening involves ultrasound, pelvic examinations, and analysis of the blood.
However, this flurry of activity among doctors is against the express recommendations of the American government. The National Institutes of Health (NIH) has recommended against routine screening, declaring that it is inaccurate and even dangerous.75
The NIH said that these tests are so unreliable that surgeons have unnecessarily operated on many women who don’t have the disease. Even if doctors do get it right, by the time the cancer shows up it’s too late. And in only a quarter of cases is ovarian cancer detected at a stage early enough for effective treatment.76
PROSTATE CANCER
With cancer of the prostate, the grape-size gland between the rectum and scrotum, medicine has been pushing to adopt routine screening of the over-fifties for the second major killer of older men. The three screening techniques include prostate-specific antigen test(PSA), transrectal ultrasound (TRUS), and digital rectal examination (DRE). However, an analysis by the Toronto Hospital in Ontario, Canada, concludes that high inaccuracy associated with these methods can also do more harm than good. The main risk is unnecessary surgery, which causes widespread incontinence and impotence in a third of cases.77 Furthermore, no evidence exists to show that men given a prostatectomy will survive any longer than those left alone and undergoing ‘watchful waiting’.
The biggest problem occurs with the PSA test, which examines the amount of a certain protein in the blood, thought to correlate with the degree of prostate cancer present. However, the prostate-specific antigen has proved indiscriminate and highly inaccurate: a recent review of the data concluded that two-thirds of men with elevated PSA levels don’t have prostate cancer.78
The problem lies with the test itself, which cannot distinguish between benign and cancerous tumours, and also with its interpretation, as doctors still disagree over what constitutes a level indicative of cancer. Newer tests are claimed to provide more accuracy, particularly when tied in with a patient’s age, but to date, the research shows that the test is worse than useless.
One study discovered that 366 men given the ‘all clear’ with a PSA test went on to develop prostate cancer, while raised values – which indicate the presence of the cancer – were found in just 47 per cent of men who in fact had prostate cancer.79 Other research from Harvard Medical School found that the PSA tests fail to diagnose prostate cancer correctly in 82 per cent of cases.80 Even when a biopsy is thrown in with the PSA test, only 40 per cent of prostate cancer gets detected.81
Recently it has been discovered that the PSA can give false readings if the man has ejaculated in the previous two days. Men over 40 have very high PSA levels immediately after ejaculating, and though these start to fall significantly only six hours later, it takes 48 hours or more for the levels to normalize.82
As with mammography, screening for prostate cancer may actually increases your chances of dying. The European Institute of Oncology in Milan found that more men who undergo PSA screening die from prostate cancer than those who aren’t screened.83
SCREENING AGAINST SCREENING
So how can you protect yourself against cancer, or – perhaps more importantly – against the screening tests themselves? Unless you have various risk factors in your family or yourself, there is no good scientific reason why you should engage in regular screening of any sort if you are healthy and have no symptoms. Professor McCormick says the most important early warning for cervical cancer (early enough in most cases for treatment) may be a persistent vaginal discharge or any sort of inter-menstrual bleeding, for instance, after coitus. The likelihood of cervical cancer increases with a woman’s number of sexual partners, whether she smokes, takes the Pill or other prescribed hormones, whether she’s had any sexually transmitted disease or began her sexual life early. If you don’t fall into any of these categories, be wary of your doctor pressurizing you into taking the test, particularly as he now stands to benefit financially from it.
If you do have to have a cervical exam, you might wish to insist on a visual examination of the cervix. In a study of 45,000 women in Delhi, India, where cytological screening is not available, visual exams picked up nearly three-quarters of the cancers found among the sample group, by means of cervical erosions which bled when touched, small growths or, in general, a suspicious-looking cervix.84
As
