I agree with John that this degree of menorrhagia is quite unusual and while it could be exacerbated by the imatinib it should be investigated fully, rather than assuming that this is just an imatinib toxicity. Actually I am concerned that this patient has not achieved CCR after more than 12 months of imatinib. It may be a good time to review this patients adherence and look for possible drug interactions. If drug adhernece is satisfactory, it may be worth considering higher doses of imatinib, however this may not be possible based on this patient's toxicity to standard dose. They should also be closely monitored if possible to ensure that they do achieve CCR (or ideally MMR) over the next 6 months.
Regards
Tim