be sure to check the travel health insurance, since many companies will NOT cover it..
so you probably will have to contract for special insurance (at a premium)..
my sister has been in and out of chemo over the past 7 years....she has 3 different kinds of cancer (small cell lung cancer, ovarian cancer and now breast cancer to add to the mix)..
after every massive treatment, she goes on a big trip shortly after she's done...
even one time when it meant a wheel chair and oxygen tanks (that trip was to hawaii)..
the trips give her something to look forward to as she suffers through the treatments....and she always enjoys herself on the trips, even when she's not feeling 100%...
and her oncologist has always encouraged her to go on all the trips....
one thing to keep in mind, besides being sure to get the special travel health insurance that will cover your wife, you have to realize that your wife will have to take it easy during the trip.....relax and go slowly....she will not be able to do what she's been able to do in the past...
you don't mention what kind of cancer she has...if you did, i'd know what kind of chemo she's getting as it makes a difference....different chemos have different impacts on the body.....some can make it difficult to walk, others have other effects...
you'll know more as it gets closer....if she does feel the need for a wheelchair, there are wheelchair companies where you can rent a wheelchair for the entire visit...and of course the airlines have wheelchairs and motorized vehicles to get you to and from the airplane...be sure to take advantage of the service if you feel it will help..
i hope everything goes well for your wife!!!