Читать книгу What Doctors Don’t Tell You - Lynne McTaggart, Lynne McTaggart - Страница 41

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