What should I do if, after choosing a Master Thesis topic, I find an existing thesis on it in another language?

I picked a very unique topic for my Masters Thesis, only to find out that there is a Dissertation on the same topic, from 2008, in French. No other books have been published on this topic.

Ugh... I really really wanted to do this. What should I do? Can I do the same topic in English? I can't even translate what the other person wrote.