In its legal battle to expand into Burholme Park, Philadelphia-based Fox Chase Cancer Center has hired the former president judge of Commonwealth Court to appeal its case to that court. After a Philadelphia judge ruled last month that Fox Chase cannot expand into the neighboring public park, the hospital dropped its former lawyers at Pepper Hamilton L.L.P., and retained James Gardner Colins at the Philadelphia firm Cozen O'Connor. Cozen filed a notice of appeal Dec. 31, stating Colins would handle the appeal before Commonwealth Court.