I that what the other poster was saying is that travel insurance typically only covers a healthy individual, not one who is already sick, unless you seek out specialized insurance (which costs a lot more)

For example, I just purchased some travel insurance, and the policy states that any pre-existing condition must be stable for at least 3 months prior to travel (meaning needing no hospital treatment etc. in the past 3 months) otherwise the insurance will not pay for treatment abroad.