Likely one of the least unpleasant things you'll have to do to kick that cancer in it's butt. I remember having to do that when I had my back surgery a few years ago, in San Antonio. The worst of those tests, for shear terror, was the stress test, with the radionuclide imaging of my heart. My EKG apparently has a hitch in its getalong or something, and so they insisted on my seeing a Cardiologist and he insisted on the stress test.
A little word of advice to all here, if you ever have to have a stress test, and they give you the option of the treadmill or other exercise device or the chemical version, take the treadmill. Because of my weight, bad knee and the bad back (herniated disk) they wouldn't let me do the treadmill. The other one is quite frightening, even when they tell you what's going to happen, and the doctor tells you he was involved, as a guinea pig, in the first tests of chemical, before they had the dosage figured out. It's something like being shoved out of a perfectly good airplane, while blindfolded. Even though you're pretty sure the 'chute is going to open, you aren't THAT sure, and you have absolutely no control over the whole affair.
ah....can you tell us what it is???