You must ensure that the surgery allows for sufficient drug uptake. Bariatric surgery will inhibit drug uptake to some degree since the stomach has less opportunity to absorb the drugs. Absorption issues are drug specific, and I do not know how much Tasigna would be affected by the surgery.
TKI drugs are primarily taken up in the stomach and duodenum, and are fairly easily absorbed. So the impact might be less than some other drugs, but there would likely be some amount of impact, and could be equivalent to taking a lower dosage. The importance of TKI drugs is greater than many other drugs, so this requires careful consideration. However, you said you are PCRU so the potential impact is less than for those who are not. There are risks, and you would need to decide whether they are manageable based on less than perfect information.
I would suggest asking your doctors some more questions before proceeding.