Heat oven to 350°F. Spray large cookie sheet with cooking spray or grease with shortening. Remove dough from both cans; do not unroll. Place dough, seam side down, on cookie sheet. Join ends of loaf to form ring; pinch ends together firmly to seal.
With sharp or serrated knife, cut 12 (1/2-inch-deep) diagonal slashes on top of dough. In small bowl, beat egg white and water with fork; brush over dough. Sprinkle with bread crumbs.
Bake 26 to 30 minutes or until deep golden brown. Cool on cookie sheet 15 minutes.
Set oven control to broil. Cut bread ring in half horizontally; carefully remove top half and set aside. Top bottom half on cookie sheet with chicken, ham, tomatoes and Swiss cheese.
Broil with top 4 to 6 inches from heat 1 to 2 minutes or until cheese is melted. Top with lettuce. Spread mayonnaise on cut side of top half of bread ring; place over lettuce. To serve, cut sandwich ring into sections.