The blood test for cancer of the prostate (PSA) is an example, writes Professor Malcolm Law at the Wolfson Institute of Preventive Medicine. Despite there being no published trials showing that early detection reduces mortality, and separate evidence that it may not reduce mortality, many healthy men have been tested and have received treatment that can cause incontinence, impotence, and other complications.
While mammography and cervical smears have been shown to reduce cancer mortality and are to be strongly recommended, breast and testicular self examination are further examples of the failure to apply scientific rigour to screening, he says.
Self examination has been widely advocated on the assumption that it must be beneficial and cannot do harm. Yet in a recent large trial, breast self examination did not reduce mortality from breast cancer but caused more surgical biopsies and thereby more anxiety. This result should discourage prostate and testicular screening.
Giving information to people considering these unproven screening tests when the only honest information is complete uncertainty is useless, argues Law, while encouraging people to decide for themselves is ducking the issue.
For a new drug, a rigorous set of experimental data must be presented before it is licensed for use. The same rigour should apply to medical screening.