Risk factors Cases, N  (%) Controls, N  (%) Adjusted OR (95% CI)a P
Net BPDE-induced & GERD
Low & GERD(-) 29 (20.3) 76 (63.3) 1.00 (ref.)  
High & GERD(-) 23 (16.1) 24 (20.0) 2.05 (0.94-4.47) 0.070
Low & GERD(+) 61 (42.7) 14 (11.7) 4.83 (2.14-10.87) <0.001
High & GERD(+) 30 (20.9) 6 (5.0) 11.54 (3.84-34.93) <0.001
P for interaction 0.835
Net BPDE-induced & smoking status
Low & never  smoking 19 (13.3) 44 (36.7) 1.00 (ref.)  
High & never smoking 15 (10.5) 11 (9.2) 2.96 (0.88-10.00) 0.081
Low & ever smoking 71 (49.7) 46 (38.3) 3.83 (1.61-9.11) <0.001
High & ever smoking 38 (26.5) 19 (15.8) 7.26 (2.80-18.84) <0.001
P for interaction 0.548
Net γ radiation-induced & GERD
Low & GERD(-) 34 (20.4) 92 (63.0) 1.00 (ref.)  
High & GERD(-) 27 (16.2) 30 (20.5) 2.64 (1.30-5.37) 0.007
Low & GERD(+) 75 (44.9) 18 (12.3) 6.42 (3.09-13.37) <0.001
High & GERD(+) 31 (18.5) 6 (4.1) 9.85 (3.50-27.71) <0.001
P for interaction       0.420
Net γ radiation-induced & smoking status
Low & never smoking 32 (19.2) 50 (34.2) 1.00 (ref.)  
High & never smoking 7 (4.2) 18 (12.3) 1.14 (0.36-3.58) 0.823
Low & ever smoking 77 (46.1) 60 (41.2) 2.25 (1.08-4.70) 0.030
High & ever smoking 51 (30.5) 18 (12.3) 6.93 (2.92-16.45) <0.001
P for interaction 0.152
Table 4: Joint effects of DNA damage, GERD status, and smoking status. a Adjusted by sex, age, BE, family history of all cancer.