Polar Bears in the Amazon
I have a patient who has done quite well for the last several years with metastatic breast cancer. Every week or so she comes in for a blood test before her chemo. Every six months the oncologist sends her for a repeat staging workup of scans and blood work. And every six months, the patient tells me how anxious she gets awaiting the results of all these tests.
So every six months, in addition to the regular blood tests, I send off tumor markers at the request of the oncologist. Three different blood tests; they have always been normal.
This time around, I asked the patient if any of those tumor markers had ever been positive, even prior to her treatment. I checked the chart to confirm her impression: no, she had never had a positive tumor marker test.
This isn't particularly unusual. Not all cancers express proteins that can be measured in the serum. But the point of "tumor markers" is that when a tumor actually produces one, it should decrease (or disappear) after treatment, and its later reappearance ought to correlate with recurrence.
So what's the point of following tumor markers when a given tumor never produced them in the first place?
Sometimes oncologists sort of go on autopilot. Time to re-stage: order tumor markers.
Testing for things you can't possibly find. I suppose it's reassuring for the patient to hear that all the tests were negative, though it seems to be akin to setting up an early warning system for polar bears in the Amazon.
Excuse me while I make a phone call. I have to knock some sense into a certain oncologist.