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Imatinib and radiation therapy-interaction

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Hi All ,

Has anyone who is on imatinib or another tki ever had radiation therapy of any kind administered at the same time for another malignancy and if so was there any interaction such as increased side effects from the imatinib or more toxic effects from the radiation;or can anyone locate any studies written up as journal articles on the subject?

I have just seen an oncologist who will treat my early stage localised prostate cancer with either external radiation beam therapy or 4D brachytherapy (the preferred possible treatment): she has trawled the literature but can at this stage find very little on the subject.She is going to seek a further opinion from my hematologist who is treating me with 400mg imatinib before coming to a final decision .We might reduce the dose or discontinue for a while but that has its risks of course. Brachytherapy is a relatively new form of treatment of prostate issues using the implantation of radioactive small iodine chips and is less invasive than surgical removal.

With best wishes

John

Hi All,

It has been decided following a discussion between my hema-oncologist and cliniical oncologist/radiation expert that there is a possibility for the imatinib to potentiate radiation toxicity.The half life of the radioactive isotope iodine-125 is long and about sixty days;half life is the time taken for the radioactivity to be absorbed into the body, in this case the prostate, and to fall to half its original value.It is possible to place a spacer in the form of a gel between the prostate and the colon for protection but very difficult to safeguard other aspects of the anatomy from radiation toxicity

We will discontinue imatinib two weeks before the brachytherapy implant procedure for a period of 2 or 3 months ;there will be monthly PCRs and if we have rising bcr/abl scores of concern would probably go on interferon alpha for a short period until it was safe to re- start imatinib.I am told that dose interruption of a tki is not uncommon and is routine in ladies with  CML who wish to become pregnant.

Does anyone have experience of dose interruption of a tki for a period of months?I know of many of you have  undergone dose reduction and/or dose cessation in the interests of TFR for a period of up to a year but that will not be my situation.

Many thanks

John

I have had to go off Sprycel several times for pleural effusions to resolve.  Starting from MR4 I lost MMR in about 9 weeks off drug.  Others have been able to go much, much longer.  It remains a mystery why there are these differences, and I wish they'd pile on the research and find out!  The good thing is, I was able to get right back down to where I'd been (and better) in a very short time when Sprycel was resumed.  This has been the prevailing experience.  Good luck - I bet you'll be able to squeak it out for enough time.

Thanks for the helpful response as this offers some reassurance that stopping for a few months is not that unusual and also not with too many great risks.

With best wishes

John