One Little Number
One aspect of Stage IV Colorectal cancer (CRC) life that remains largely unknown to the rest of the world is how much your life can be dictated by one little number – that usually arrives by email once a month. A brightly wrapped e-present in your in-box which may determine minor little things (ha)… like if your treatment is working; if it is failing; if you remain in remission (NED – No evidence of disease); if your cancer is back in a recurrence. It is the CEA biomarker.
CEA stands for “Carcinoembryonic antigen” which are glycoproteins expressed in GI-tissues (and to a lesser extent a few other tissues) during fetal development. They normally stop being expressed in high levels after birth. There is a simple blood test to monitor for it if you have CRC.
Some patients’ tumors shed huge amounts of CEA. I have many friends who have had levels approaching 1,000 µg/L. That is just in my friends circle, I am sure clinically, values >1,000 µg/L are seen. Then there are patients whose values never exceed “normal levels” (for non-smokers approximately 2.5-3.8 µg/L depending on the testing site), no matter how extensive their disease is. Finally there are a group a patients who are in-between these two extremes.
Some patients’ CEA levels are exquisitely well correlated to their disease (they know exactly how their disease is regressing or progressing based upon how their CEA number fluctuates). In other patients, there is a much less (or sometimes even zero) clear correlation.
Where do I personally fall on those spectrums? In some ways I think I fall in the worst group of people (I know, I know the grass is always greener…). My CEA levels rise a little as my disease advances. Although their direction tends to correlate with disease state – due to the small numbers involved, these patterns are smack dab overlaid with the “error-bars” inherent in the assay. So… I get data that tends to indicate how my disease is doing but with big error bars. In science there is a phrase commonly used “Junk data is worse than no data”. I’m living that adage. Except my data isn’t always junk data – just sometimes. And the data potentially has huge impacts on my life.
Best of all worlds huh? 🙂 By the way, did you know that the sentiment that “The grass is always greener on the other side of the fence” was written as long ago as the Roman poet Ovid when he mused “The harvest is always more fruitful in another man’s fields”. That is why I love history. Details change but human nature is constant.
One little number: 6.7
An email arrived in my in-box last night. I could see from the subject line that it was my CEA results. I opened it optimistically. Before I started my recent, relatively harsh, FOLFIRI chemotherapy my value had been 8.2 µg/L (its historical highpoint – why I started FOLFIRI!). After only two infusions (and a long Christmas break) it lowered 25% to 5.9 µg/L! Woo-hoo! “The FOLFIRI was working – all the side effects were worth it!” went through my mind when that email arrived in January. So, I was optimistic to quickly open last night’s email. If my CEA dropped so much after only two infusions, I expected it to continue to plummet after more. The CEA result: 6.7 µg/L. Wait… 6.7? That’s the wrong direction!
Instantly my heart sunk.
The scientist side of my brain made some very quick points to the patient side of my brain.
- Fluctuations of 0.8 µg/L are fully within the error-bars of the experiment
- I had a continuous cough for 12 months prior to starting FOLFIRI. Doctors attributed it to a long-term infection/related inflammation. As a person with lung tumors – let’s just say I had my doubts on that diagnosis……. The cough magically disappeared within days of me starting FOLFIRI (YES!!) as a very suspicious potential clinical sign of chemo success. It remains gone.
- Aside from chemo side effects I feel GREAT, with high appetite & just yesterday I hit my highest weight ever as a cancer patient – all clinical signs of a successful treatment!
But that is the psychological power of one little number… I may be a scientist but I’m not looking at a graph of results coming from a cellular assay. I am looking at a number indicating whether my current chemo is working or not. And there aren’t that many remaining available FDA-approved chemo choices left, if it isn’t…
Scientifically I have no reason to worry. The number generated in last night’s test was “statistically insignificant”. Personally, it plowed into my terminal optimism like a ton of bricks as I prepared to go to bed.
I woke up with my terminal optimism mostly back in force. The data will become more clear when I get a CT-scan next week. Ironically, a CT-scan intentionally scheduled to continue to work towards “my greatest research project ever: me!” (which although I am very excited about, I still am not ready to update you on – sorry, I never discuss half-done still-fluid projects – too many moving parts 🙂 )
I’ll get those scan results in about a week. Probably they will show my FOLFIRI chemo working. But until then, I will have a nagging voice of worry in the back of my ear. This is something that CRC patients deal with on a constant basis. Is their (often harsh) treatment working? What treatment will they need to try next if it isn’t? Is there an approved treatment to try next?
I remain terminally optimistic. But I’m human. The power of one little number.