Blood Tests and Tumor Markers in NSCLC
Information on the importance of biomarker testing and actionable genetic mutations can be found in this more recent article.
When I was diagnosed with metastatic adenocarcinoma of the lung, my particular flavor of NSCLC, it was considered a fairly "vanilla" variety of lung cancer. There were no known actionable mutations in my tissue sample, so I was put straight away on a cocktail of carboplatin, Alimta, and Avastin. Treatment started. I seemed to handle it fairly well. And then, almost right away, people began asking me about my blood markers.
Should I be looking for blood markers?
I honestly had no idea what they were talking about. While waiting for my initial diagnosis, I had done a lot of research into lung cancer and I had not come across anything to indicate that I should be looking for blood markers. I was repeatedly asked about my carcinoembryonic antigen (CEA) levels by concerned acquaintances. This magic number was supposed to tell me whether my treatment was working, apparently, yet I had no idea what my CEA numbers were. It worried me.2
Here I was, being treated by a man who was considered one of the top oncologists specializing in lung cancer -- surely he was monitoring these numbers. But when I asked about them, he simply said that there were no blood markers for my cancer that would tell us anything. So why were so many people asking me about them?
Concerning increase in CEA levels
The truth is that blood markers are very useful for predicting or monitoring some types of cancer, especially cancers of the pancreas or colon, and it turns out that many of the people asking me about my CEA levels had experience with colon cancer, where that number is a more reliable predictor of treatment success.
It, therefore, came as a surprise to me, a couple of years down the treatment road, when my oncologist expressed some concern about an increase in my CEA levels. I had been under the impression that these were useless numbers -- he had said so, himself, after all. But this was during a different treatment. I was off the chemotherapy and had been on a targeted drug for months.
Signs my tumor was progressing
Sometime after my biopsy and before I showed progression of my tumor during chemotherapy, a mutation in my tumor became actionable. We knew this was likely to happen, or possible at the very least, based on the rapid pace of genetic research going on in the cancer field. I had a liquid biopsy done as soon as we confirmed progression and then began to target the best possible mutation that had shown up. But there were a number of indications that the targetted drug was not working, including a sudden elevation in my CEA numbers.
It turns out that these numbers are relevant to NSCLC, though only in certain cases, though they may not be completely reliable on their own. They are not suitable predictors of cancer because elevated levels of several types of these markers can occur in healthy individuals for various reasons. And they were useless as measurements of success during my initial treatment period.
But they may be highly useful in indicating a recurrence of cancer after successful treatment. Or, in my case, an indicator that my tumor was continuing to progress under a targeted therapy. A sudden spike in these numbers caused enough concern to re-evaluate my condition and get me off one drug and onto another.
A small piece of the puzzle
The CEA number alone was only a small piece in the diagnostic puzzle, and one that I may not hear about again during my regular follow-ups. And they may or may not be useful for other lung cancer patients. At this point, it seems that only patients with a few actionable mutations are likely to see any benefit from monitoring these levels, and perhaps only with limited value.
Still, the complicated process of treating advanced lung cancer relies upon an ever-expanding toolbox. I'm glad to have that number in there, even if it is barely used and I never expect to hear it mentioned again. And who knows, maybe next time I am in the market for a new treatment, I will be introduced to yet another marker or mutation that nobody knows about today.
Editor’s Note: We are extremely saddened to say that on October 21, 2018, Jeffrey Poehlmann passed away. Jeffrey’s advocacy efforts and writing continue to reach many. He will be deeply missed.
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