The assumption that medical screening can help detect diseases early enough and save lives is not always true. With a plethora of tests available, screening has become confusing and conflict-ridden.

A good example is ovarian cancer screening. Recently the US Preventive Services Task Force (a body designated to advice on the validity of screening tests) stated that women with an average risk of ovarian cancer should not be screened for the disease. The American Cancer Society concurs.

The no-screening recommendations were based on a 13 year long large scale study of 78,000 women aged between 55 to 74. Half of these women underwent ultrasound examination and blood tests (which include studying biological markers for cancer), and the other half were not screened. Surprisingly at the end of the 13 years there were no differences in death rates from ovarian cancer in the two groups. Crucially, 10 per cent of those screened (about 3,200 women in the study) had 'false-positive' results which led to over 1,000 women requiring unnecessary surgery to remove their ovaries. Obviously there were complications from the surgery such as infections and blood clots. What happened?

The ultrasound revealed benign ovarian cysts which could not be distinguished from malignant cancer without surgery. Furthermore, the blood markers which were supposed to detect cancer were sometimes elevated for reasons other than cancer, not an uncommon finding with screening tests. But habits die hard and many doctors continue to screen for ovarian cancer, regardless of these findings or recommendations.

Unfortunately, these controversial screening tests are not limited to ovarian cancer alone. Controversy, for example, rages on about prostate cancer screening for elderly men. Some studies have shown prostate cancer tests to be beneficial and many others have not. Despite minor benefits, potential harm from biopsies, over diagnosis (finding cancer that would never become clinically detectable), and treatment complications have to be strongly considered.

In all this confusion, it is almost tempting to take a fatalistic stance and not perform any tests. But that would be counterproductive because there are many well-established and useful tests for appropriate age groups such as PAP smears, colonoscopy, dermatological check for melanoma, and ultrasound screening for aortic aneurysms to name just a few. If you have the financial resrouces (as there is no universal insurance in Nepal), these tests are indeed useful and highly recommended.