UPMC faces having to review contracts for up to 700 of its doctors after Highmark terminated them from its network effective Jan. 1. How many contracts will have to be tweaked as the result of Highmark's Nov. 20 decision is unknown, but health lawyer Michael Cassidy, said the impact would be "significant." "It's going to be a significant issue," said Cassidy, who chairs the health law practice group at the downtown offices of Tucker Arensberg. "Some doctors will have protection, some won't." At issue is patient volume and other productivity standards that are baked into every doctor's contract when they work for a health system.