Below is an instruction from Human. Write a response.
    ### Instruction:
    Who is at risk for Smoking and the Digestive System? ?
    ### Response:
    Smoking has been found to increase the risk of cancers of the3
                
- mouth  - esophagus  - stomach  - pancreas
                
3
                
,
                
4
                
,
                
5
                
- liver  - colon  - rectum

    