Tumor Markers and Scans

A few weeks ago I had a CT scan plus tests for 5-HIAA  and chromogranin A (CgA).  The CT scan measures the visible tumors and is compared against the prior one to see if there are any changes.  The good news is that my visible tumors as seen by CT scan are stable.  I will be getting an MRI at the end of the month to see my liver tumors better.  I have some small liver tumors but all of the specialists I have seen since diagnosis think I have reasonably low liver involvement.  This will be my first MRI so I guess it will be used as a baseline to see how my liver tumors progress. 

In terms of my tumor markers, these are tests that measure the activity or secretion of hormones by the tumors.  The CgA marker is a general measure of tumor activity.  The 5-HIAA test is a 24 hour urine sample that measures the level of serotonin that the tumors are producing.  In most patients with carcinoid cancer, the levels of CgA and 5-HIAA are elevated. 

Any lab tests (not just tumor markers) are shown with the result that was measured and a range of what is considered normal. This is called called the reference range.  If you have lab tests over time that are from different places with different ranges, one can divide the result by the top of the reference range to see the percentage over or under the range. The CgA table below shows some of my results from this test since my initial diagnosis in August, 2010.   Before I started taking Sandostatin, my result was 1,243 when the top of the range was 50.  My result was 25 times the top of the normal range!  Once I started Sandostatin LAR, the results, while still high relative to the range, were much lower, averaging around 2x the top of the range.  Just after my surgery in September 2013, my CgA level was 43 or half the range; the following test in January 2014 was at the top of the range.  Subsequent tests have been climbing with my most recent test at 3.38 times the top of the range the highest since just prior to my surgery.  From what I understand, CgA is a vague diagnostic marker and having this test elevated in the absence of other symptoms or tumor growth is not enough to take action.  My doctor did not seem too concerned with this CgA reading, despite the fact that it is rising. 

CgA
	Result	Ref Range	% Over/Under Range
8/30/2010	1243	<50	24.86
8/15/2012	585	<225	2.60
2/14/2013	236	<93	2.54
4/5/2013	182		1.96
8/9/2013	295		3.17
10/4/2013	43		0.46
1/15/2014	93		1.00
2/13/2014	89		0.96
3/14/2014	109		1.17
6/5/2014	140		1.51
7/10/2014	138		1.48
10/1/2014	314		3.38

5-Hydroxyindoleacetic acid (5-HIAA), the major metabolite of serotonin, is excreted in the urine.  This test is more highly specific to carcinoid tumors.  Elevated levels of serotonin as measured by 5-HIAA are associated with heart valve problems caused by fibrosis.  Fibrosis is defined as an abnormal condition in which fibrous connective tissue spreads over or replaces normal smooth muscle or other normal organ tissue.  Not too much seems to be understood about the relationship between serotonin and fibrosis and many people who have high levels of serotonin do not get fibrosis. There must be some other hormone or process involved.  Nonetheless, reducing the levels of serotonin, which is a hormone released by carcinoid tumors, is a major goal of most doctors.  Sandostatin LAR is known to inhibit the release of serotonin. 

When I was first diagnosed with carcinoid cancer in 2010, my 5-HIAA was over 4x the high end of the normal range (see table below).  Despite being on Sandostatin LAR for about 2.5 years prior to my surgery in 2013, my 5-HIAA levels remained at that level.  When I had my debulking surgery and about 90% of my tumors removed, my 5-HIAA came way down to near the top of the reference range.  My most recent test shows a  slight increase in 5-HIAA but nowhere near where it was pre-surgery. 

5-HIAA
	Result	Ref Range	% Over/Under Range
9/8/2010	74	<18	4.11
2/15/2013	33	<8	4.13
1/16/2014	7.6	<8	0.95
10/2/2014	8.2	<8	1.03

So what does this all mean?  I’m really have no idea.  I’m glad my serotonin is closer to normal now that I’ve had surgery. But since I was not having any signs of heart valve disease or fibrosis prior to surgery, I’m not sure it really matters.  I’m not too sure what to think about the rising CgA but since my doctor is not worried, I won’t be either.