It depends upon what the doctor reports.
The fact she had cancer is not itself sufficient to determine she is medically inadmissible. The question they will ask is "what are the estimated costs to treat her condition over the next 5 or 10 years". Someone who had cancer 4 years ago and simply requires routine follow-up would NOT be medically inadmissible.
IF the medical officer decides that she may create excessive demand, you will receive a fairness letter that is supposed to set forth the diagnosis and the estimated costs of treatment for her condition over the 5 or 10 year period considered. You would then have three options:
(1) Ignore the letter. You would be refused ("medically inadmissible due to excessive demand").
(2) Challenge the medical opinion. This would consist of having letters from doctors stating what the real expectation is. You can also challenge the cost estimates, but this is surprisingly difficult to do.
(3) Present a mitigation plan. This could include private insurance coverage, analysis of the coverage in your intended province and how much of the actual cost would be born by the provincial health system, etc. These plans can be quite successful, but you need to work with one of the few experts in this field to do it - this is NOT a do-it-yourself type situation generally, although I will answer questions you have if you get to this point because I've educated myself on this area.
If you choose (2) and/or (3) and are still denied you can challenge the decision in Federal Court. The outcome for FSW applications in this area are quite good - about 75% of cases heard by the court are actually granted. CIC is definitely struggling with excessive demand medical inadmissibility.
So my advice: make sure her doctors are willing to write her letters now that state her condition is stable and she is not expected to require anything other than routine monitoring and follow-up. That makes it very likely that you'll never even GET a fairness letter - and that is definitely the best way to approach this problem.
From what you've described, I suspect you won't have an issue.
Good luck!
