Tumour markers revisited
It’s still happening in Malaysia where some private labs offer routine “cancer marker” screening to otherwise normal people. When used routinely there are many problems as this Malaysian doctor pointed out in our Facebook page:
Hi guys, I am a Malaysian doctor currently working in Australia. I am wondering if there’s an avenue I could pursue to help push for pathology labs in Malaysia to require doctor’s requests to perform harmful tests such as tumour marker for “cancer screening” in asymptomatic population. I am sure all of us have had experience with our family and friends approaching us with their elevated CEA and CA 19-9s and asking for advice, and in an asymptomatic group this only causes undue anxiety and unnecessary CT scans which may necessitate biopsies for incidentalomas that may be found in the scan. A friend of mine approached me as his dad has a raised CA 19-9; he’s 70 and totally asymptomatic. He’s now super worried about to prospect of having cancer, and the sad thing is he’s one week away from his 70th birthday and is now having unnecessary concerns from this test that shouldn’t have been done in the first place. I looked up literature and it’s evident that the positive predictive value for a positive CA 19-9 is only 0.5-0.9%! So this friend’s dad will now visit a doctor, and for medicolegal concerns I suspect most doctors will at least order a CT Abdomen to allay his concerns. False positives are only one side of the coin, I am worried about the false negatives too. As you would know a very substantial patients with ACTUAL cancer will have negative tumour marker, so just imagine someone who’s symptomatic who decided to do the blood test and is falsely reassured by a falsely negative result, hence delaying the necessary treatment. How many times have we all heard our friends say “yay my tumour marker is negative”? I propose that Malaysian health authorities should make those unregulated tumour marker screenings illegal as it causes more harm than good in the general population. It is clearly an irresponsible money-making avenue by pathology labs with disregard for the consequence it has on our unsuspecting family and friends.