CT / PET Scans: This may be a dumb... - CLL America Support

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CT / PET Scans

JeannineMarie
JeannineMarie

This may be a dumb question but it is one I cannot locate an answer to.

How many scans in a year would be too many? If I do the CT scan scheduled for me in October that would be 5 CT's within the year. That and the fact I had many x-rays done this year due to pneumonia and VAT's surgery. Have been reading that we should limit scans due to the possibility of a secondary cancer. Any one have an answer?

3 Replies
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Hi JeannineMarie,

There are many varying opinions that attempt to answer your exact question. Wayne Wells on the CLLForum wrote a 5 part essay, I think several years ago. I will try to find those and send you links

When I used some of his links/references, I calculated my exposure from my CT Scans on a clinical trial. Those each were both chest & abdomen and head & neck, which resulted in 2 separate scans in a single session. When I added up the exposure, 3 sets of those were above the allowable annual exposure for a worker under the USA NRC in a Nuclear Power Plant. So I set my own limit of 2 combos or 4 individual scans per year.

The doctors will tell you that a single CT Scan has minimal impact on your risk of cancer, but other information indicates that the sum of all radiation exposure over your lifetime does increase the risk of cancer.

Len

The conventional wisdom by CLL specialists is that, outside of clinical trials, except in certain circumstances, CT scans are not called for with CLL, and PET/CT would only be called for if there was suspicion that CLL has undergone transformation to an aggressive lymphoma (Richters transformation). You should ask your oncologist why he/she wants to do a CT scan. And 5 in a year is a lot.

Here is the response from ThreeWs

healthunlocked.com/user/thr...

My ramblings on CT scans are a permanent part of CLLSOCIETY.org and here is the page below with the two articles.

cllsociety.org/beyond-the-b...

The most relevant article is the one reporting the findings of a nationwide Taiwanese study that is as close to shedding some light on your question that I have found.

cllsociety.org/2016/03/ct-s...

I tried to fairly represent the relative findings as they might apply to our community while pointing out the difficulty in attributing any direct correlation due to a set of factors that I highlighted. The one area I did not elaborate on which could be very important is the degree to which each individual patient has a functioning immune surveillance system. The data shows us that, aside from ionizing radiation imaging, CLL patients are at higher risk for secondary cancers period. That tells us the immune dysfunction is not confined to the humoral immune B lymphocytes and that the risk is variable within the patient community.

As you well are well aware those with 17p- are likely to have damaged or deleted TP53 genes and there are many more tumor suppressor genes that can be compromised that are complicit in the elevated risk for secondary cancers to emerge. Compounding the risk is exposure to chemotherapy which can and will provide acute windows of depressed immune response to damaged DNA that can be incorrectly repaired creating an oncogene and later develop into a cancer.

You have been through more than most of us, including yours truly, with high risk CLL and having been beaten up by multiple therapies so on the face of it you are likely to be in a state of higher vulnerability to poor DNA repair leading to a later cancer than someone who has gone into a Trial as a relatively indolent CLL patient with intact TP53 and ATM genes like me and who avoids chemo (I only had 2 cycles of FR) through use of a KI like Ibrutinib. I should note that I understand that a mutated or deleted TP53 gene should be confined to the B lymphocyte cancer cells in CLL as that important gene is carried in all other tissue cells but there are enough patients who go on to develop multiple secondary cancers that suggests that at least in some patients there is a globalized immune dysfunction of TP53 and or other tumor suppressor genes that is not understood. Skin cancers are another example of a different tissue clearly and commonly affected by the patient’s CLL immune response dysfunction.

Bottomline: I don’t think you can put a number of scans as a danger or safe threshold for any patient. Weigh the need, benefit and reason for each scan before giving consent. I don’t like the number (30+) of scans that I have had but if it weren’t for the Ibrutinib Trial and its requirement for scans I would not be here to write to you on this subject.

I think about your enduring battle and tip my hat in recognition for your effort.

WWW