Wether you can break you lease isn't the real question. The real question should be what are the possible ramifications if you do break your lease. This is going to vary depending on the terms of you lease, and the tenant/landlord laws in your state. You may want to speak to a local property manager and/or Real Estate attorney to discuse what recouse your landlord may have.
If there is the chance of recourse from your landlord, this doesn't mean you should hold off on your move. However, I would recomend having a conversation with your landlord to make him aware of your intention, and also to discuse the best way to go about breaking your lease without causing to much trouble for your landlord. This discusion may include comming up with an appropriate timeframe for your notice (ie: 30-60 days). I would also recomend being willing to let the property be avialable for your landlord to show it to prospective renters before you've moved out of the property. This would show to your landlord that you understanding of his position and that you are willing to make sure the property doesn't have a vacancy period as a result of your breach.