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Friday, 26 December 2014

The Inefficiency of NETs

Sorry, I'm aware that I've written quite a bit about Neuroendocrine Tumours (NETs) recently; probably just subconscious worry about the CgA/CgB tests I'm scheduled to have in January.

Quick recap., feel free to skip: 
I'm 16, and in June 2014 I went to the UCC at Burnley Hospital in the middle of the night with severe pain in my abdomen, and was bounced to Blackburn Hospital's surgical unit, where a couple of days later I had an emergency appendectomy (surgery to remove my appendix) due to appendicitis, for which I was told I would not have follow-up.

Around three weeks later, I was summoned rather oddly to Burnley Hospital, where I was told by a surgeon I had never met before that I had had a Neuroendocrine Tumour in my appendix. It was tiny, Stage T1 (<2cm in size), but I had a whole range of blood tests (including Chromogranin A/CgA) and a 24-hr urinary 5-HIAA collection (eugh) which were going to be done that day. I have weird veins, so they sent me to paediatrics. Turns out one test was fasting and I couldn't have it done because I'd eaten, so we rescheduled them. 

A week later, we were told I had to have my CgA done again, as it has to be frozen within 15 mins of being collected, so to the hospital we went.
About a month-and-a-half into my first year of college (sixth form, 16-18) I received a letter giving me the All Clear :D

Over a month ago, I began getting worse and worse pain in my abdomen, diarrhoea at night, flushing, headaches, chest pain etc.. I went to see my GP a couple of weeks ago, and a CgA+CgB test was ordered for me, which has yet to be done. A few days ago, I got a letter from the hospital with an appointment to see the Consultant General Surgeon who told me about the NET. Presumably he has to authorise the tests and wants to see me first.

***

So basically, that's me.

I was reading into the CgA tests and realised just how inefficient they are compared to other tumour marker tests.

PSA is a marker for prostate cancer. ~98% of men with fast-growing prostate cancers have high PSA levels. However, CgA is a marker for carcinoid and other NETs. Only 73% of people with any type of NET have elevated CgA levels. That's still pretty good compared with CEA, a marker for colorectal carcinoma, where less than 25% of people with cancer in the colon have raised levels, and only around 50% of those with metastatic disease have higher levels. But it's still a 27% chance that the test won't pick up a NET or ten.

Not only that, but the relatively slow turnaround time for CgA results is kind of crazy. The PSA test has an average turnaround time in the laboratory of 1-3 days. For the CEA test, it is less than 24 hours. CA-125 is a marker for ovarian cancer, and the turnaround is 1 day. For CgA? 1-3 WEEKS.

So, while you're waiting, your cells may be multiplying at an unfathomable rate. Fair enough, many carcinoid and NE tumours are slow-growing, but still a decent amount - and most in children and teenagers - are high-grade, fast-growing tumours. In three weeks, they could spread to other organs, or at least grow considerably.

Another issue is the large difference in what different labs consider to be 'normal' ranges. One lab sets the upper end of normal at 36ng/ml, while another lab sets it at 96ng/ml, and yet another lab sets it at 245ng/ml. What?! How is anyone supposed to know whether their levels are normal or not? I suppose a diagnosis is made on a combination of factors, such as CgA, 5-HIAA, other hormones and imaging such as CT scans and OctreoScan. But still...

Finally, it's actually a somewhat inconvenient test. It has to be frozen within 15 minutes of being taken, so it cannot just be taken at a blood clinic and sent to the hospital. It has to be done at a hospital with the right facilities for testing CgA. In my case, the nearest one is Blackburn which is a good 30 minutes away from my house, and about 45 minutes from my college, or over an hour by bus. It is also an unusual test, which many GPs are unlikely to have to order, ever. I get the feeling that some doctors don't even know what a CgA test is, which doesn't exactly instil faith in me. 

Correct me if I'm wrong, by all means. But to me, it sounds like a test that needs refining. And medical professionals need educating about NETs.

Is that really too much to ask?

~Liz