can you stuff lettuce leaves and cook like stuffed cabbage

I'll go along with the steaming suggestion. Those inexpensive Chinese steamer baskets are perfect for this.

Tanks to everyone will try all.

Alternatively, you could steam them - something I often do with dumplings and other delicate creations. That might help keep your leaves intact. Just make sure, like inpatskitchen says that your filling is mostly cooked.

If you do want to cook them like a traditional stuffed cabbage, choose sturdy lettuce leaves, blanch them for just a few seconds to soften them and stuff them with a filling that is near cooked before baking or simmering on the stove top.

Boulangere's recipe for "summer presents" is a wonderful stuffed lettuce recipe. http://www.food52.com/recipes/12930_summer_presents