Advantages to the Wealthy vs. Disadvantages to the Poor or Fairness in Wealth Distribution; Man-made vs. Naturally-made, as in the Mockingjays or Tracker-jackers and the many obstacles created specifically for the Games; Abuse of Power; Human Rights; "Big Brother" or government control; Rebellion or Revolution...
Also evident are themes of survival and self-preservation, personal independence, and even a Robin-Hood type mutiny against authority.
I think that the theme is that everyone is there own person and nobody belongs to anyone else. This is proven throughout the story because the Districts are thought to be "owned" by the Capital, which is not neccessarily true.
Also another theme could be the things that go wrong in society. Such as starvation, war, unequality, violence, etc. The purpose of the theme is to get the reader thinking about what the author is trying to get across throughout the entire book/story. It is a message that goes along with the story but can also affect anyone.