· The ones that work
Cervical smear tests More than four million women are screened annually in England, preventing up to 3,900 cases of cervical cancer each year, according to the DoH. A recent pronouncement by the National Institute for Clinical Excellence (Nice) suggests that a new method, using liquid-based cytology (LBC), may improve the quality of cell samples sent to the laboratory for screening and reduce the number of mixed-up or contaminated smear results.
Mammograms Reduce breast cancer mortality by about a third in women over 50. Some doctors have called for the introduction of routine mammograms for women as young as 40 but, while trials have been done, they are too small to determine whether mammography really does reduce mortality in women aged 40-49. Less effective (and possibly not useful at all) in women under 50 because breasts are denser.
Colon cancer Randomised trials have established that screening (based on detecting blood in stool samples) reduces mortality; the next step is to introduce screening on a pilot basis.
· The ones that may work
Ovarian cancer Trials are under way on a blood test plus ultrasound screening.
Prostate cancer Trials are under way into whether offering the PSA blood test to all older men will save lives. Autopsies on elderly men who have died from other causes commonly find prostate cancer too.
Lung cancer There is a possibility that a spiral CT scan may detect lung cancer in high-risk patients. There is some pressure from the US to introduce this in Britain.
Melanoma There is evidence that patient education of high-risk groups may lower the risk of death from this type of skin cancer.
The ones that don't
Lung cancer Trials done 20 years ago indicated that plain test x-rays in smokers did not lead to a reduction in lung cancer mortality.
Breast self-examination Trials found that formal breast self-examination for lumps did not reduce mortality rates from breast cancer.
Testicular self-examination Has not been tested in a trial. But most believe this is not effective.
