According to Gemini, radiation related cancer rates aren't higher in high elevation cities like Quito or La Paz... Shouldn't they be too? Airliners fly a lot higher but people live in these 24x7.
So a flight attendant that clocks ~700h a year, that's roughly 5 years of living in Quito in a year of flying in Sieves. Now, given that the air crew studies are not all that conclusive yet, take high-altitude populations at 5x less exposure and all these other factors I've mentioned, and they will end up having an even lower chance of showing up in any cancer studies.
So... not remotely comparable.