Table 1.

Demographic and clinicopathologic characteristics of the study population stratified by smoking status

The entire populationThe IMRT/3DCRT cohort
Never smoker (N = 947)Former smoker (N = 168)Current smoker (N = 734)Never smoker (N = 267)Former smoker (N = 48)Current smoker (N = 180)
FactorN (%)N (%)N (%)PN (%)N (%)N (%)P
Age group<0.001a<0.001a
 ≤3085 (9.0)2 (1.2)36 (4.9)25 (9.4)1 (2.1)9 (5.0)
 31–40311 (32.8)25 (14.9)167 (22.8)85 (31.8)6 (12.5)47 (26.1)
 41–50289 (30.5)57 (33.9)243 (33.1)88 (33.0)22 (45.8)56 (31.1)
 51–60174 (18.4)55 (32.7)192 (26.2)43 (16.1)9 (18.8)38 (21.1)
 61–7073 (7.7)24 (14.3)82 (11.2)22 (8.2)8 (16.7)25 (13.9)
 ≥7115 (1.6)5 (3.0)14 (1.9)4 (1.5)2 (4.2)5 (2.8)
Gender<0.001<0.001
 Male509 (53.7)163 (97.0)726 (98.9)157 (58.8)45 (93.8)175 (97.2)
 Female438 (46.3)5 (3.0)8 (1.1)110 (41.2)3 (6.2)5 (2.8)
Drinking status<0.001b<0.001b
 Never908 (95.9)125 (74.4)537 (73.2)259 (97.0)37 (77.1)120 (66.7)
 Former6 (0.6)17 (10.1)5 (0.7)3 (1.1)5 (10.4)3 (1.7)
 Current33 (3.5)26 (15.5)192 (26.2)5 (1.9)6 (12.5)57 (31.6)
VCA-IgA0.0010.005
 ≤1:160465 (49.1)81 (48.2)292 (39.8)149 (55.8)24 (50.0)72 (40.0)
 >1:160482 (50.9)87 (51.8)442 (60.2)118 (44.2)24 (50.0)108 (60.0)
Histological type0.348b0.296b
 I4 (0.4)1 (0.6)1 (0.1)1 (0.4)0 (0)0 (0)
 II56 (5.9)7 (4.2)32 (4.4)20 (7.5)1 (2.1)7 (3.9)
 III887 (93.7)160 (95.2)701 (95.5)246 (92.1)47 (97.9)173 (96.1)
T-stage0.042a0.004a
 T1144 (15.2)25 (14.9)80 (10.9)51 (19.1)8 (16.7)21 (11.7)
 T2250 (26.4)41 (24.4)198 (27.0)74 (27.7)10 (20.8)38 (21.1)
 T3356 (37.6)68 (40.5)271 (36.9)99 (37.1)21 (43.8)75 (41.7)
 T4197 (20.8)34 (20.2)185 (25.2)43 (16.1)9 (18.8)46 (25.6)
N-stage<0.001a0.066a
 N0175 (18.5)54 (32.1)94 (12.8)61 (22.8)18 (37.5)38 (21.1)
 N1555 (58.6)82 (48.8)390 (53.1)150 (56.2)22 (45.8)96 (53.3)
 N2190 (20.1)25 (14.9)203 (27.7)45 (16.9)7 (14.6)37 (20.6)
 N327 (2.9)7 (4.2)47 (6.4)11 (4.1)1 (2.1)9 (5.0)
Clinical stage<0.001a0.015a
 I51 (5.4)14 (8.3)25 (3.4)23 (8.6)6 (12.5)11 (6.1)
 II269 (28.4)42 (25.0)170 (23.2)81 (30.3)9 (18.8)38 (21.1)
 III408 (43.1)72 (42.9)316 (43.1)111 (41.6)23 (47.9)78 (43.3)
 IVa192 (20.3)33 (19.6)177 (24.1)41 (15.4)9 (18.8)44 (24.4)
 IVb27 (2.9)7 (4.2)46 (6.3)11 (4.1)1 (2.1)9 (5.0)
Chemotherapy<0.0010.098
 No225 (23.8)59 (35.1)149 (20.3)69 (25.8)18 (37.5)40 (22.2)
 Yes722 (76.2)109 (64.9)585 (79.7)198 (74.2)30 (62.5)140 (87.8)
Radiotherapy0.504b
 IMRT246 (26.0)45 (26.8)166 (22.6)
 3DCRT21 (2.2)3 (1.8)14 (1.9)
 CRT680 (71.8)120 (71.4)554 (75.5)

NOTE: A former smoker was defined as an individual who had not smoked for 12 months or more at enrollment.

  • aKruskal–Wallis test.

  • bFisher's exact probabilities test.