I write in response to the article by malaysiakini 's columnist KJ John titled Who betrayed my friend?

His frustrations on the late diagnosis of colon cancer afflicting his close friend are understandable. After all, how could doctors have 'missed' the cancer after so many medical check-ups? How reliable are our routine medical check-ups?

A colonoscopy is never a routine procedure included in most packaged health screening tests. Colonoscopy is usually not offered unless the individual becomes symptomatic or has a high risk of developing colon cancer. High risks include a previously diagnosed colonic polyp or a strong family history of colon cancer. Unfortunately, many colon cancer patients remain without symptoms and the disease is often discovered late.

The only test that has reliability and can be easily performed is a feacal occult blood test. This is a test to detect minute amounts of blood in your stool. Any positive result will warrant further investigation. A negative result, however, may only give false reassurances.

Tumour markers are often a favourite addition in health screening packages. However, they have been proven to be useless as a screening tool. Nevertheless, they remain widely used, often giving a false sense of security.

Newer methods of using non-invasive methods like a CT scan or MRI (magnetic resonance imaging) are still under evaluation for their usefulness as a screening tool. Advanced digital software can give the radiologist a virtual colonoscopic experience. They are not yet widely available and the sensitivities of these methods are not yet proven.

At this point in time, it remains controversial as to whether anyone above 50, deemed at a higher risk than the general population, should be given appointments for a colonoscopy. One could argue either way. On one hand, you could detect cancerous lesions much earlier and on the other, it is an unpleasant test not without its own risks.

The fact is, many issues remain contentious, even for medical professionals.