Advice on Road Bike Brakes?

I have this 90s Cannondale Road bike with some old brakes that are giving in. I'm interested in buying some new brakes like Shimano BR-6600s or some sort of newer 105s. Sometimes the brakes mention "Must be used in conjunction with ST-7900 or ST-6700 STIs for correct leverage ratio" does that mean I have to buy levers too? Or could I just use new brakes with my current levers. Thanks.