Meanwhile, cook cabbage in boiling water just until outer leaves pull away easily from head. Set aside 8 large leaves for rolls. Refrigerate remaining cabbage for another use. Cut out the thick vein from the bottom of each reserved leaf, making a V-shaped cut.
In a small nonstick skillet coated with cooking spray, saute onion until tender. In a large bowl, combine the rice, onion, egg whites, currants, pine nuts, lemon juice, oregano, pepper, salt and cinnamon. Crumble beef over mixture and mix well.
Place about 1/3 cup beef mixture on each cabbage leaf. Fold in sides, beginning from the cut end. Roll up completely to enclose filling. Place seam side down in a 13x9-in. baking dish coated with cooking spray. Combine the tomato sauce, brown sugar and thyme; pour over rolls.
Cover and bake at 350° for 1 hour or until cabbage is tender and a thermometer reads 160°. Uncover; bake 5-10 minutes longer or until sauce reaches desired consistency.