The English plural is carcinomas. The Greek/Latin plural would be carcinomata.
Latches.
circus's
daddies.
axes
slides
Clouds
That is the correct spelling "princesses" for more than one princess.
I think perhaps you are trying to spell countries, as in more than one country.
spell it out - there is more than one ADEA
Trophies
One activist. Several activists.
More than one blog=blogs.