Table 1 Characteristics of the individuals included in the study
| Â | Healthy subjects* | ESCC patients* |
|---|---|---|
Gender | ||
 Male | 27 (33%) | 50 (78%) |
 Female | 55 (67%) | 14 (22%) |
Age (median and range) | 58 (20–85) | 59 (39–78) |
Tobacco smoking | ||
 Never smokers | 48 (60%) | 1 (3%) |
 Former smokers | 13 (25%) | 6 (17%) |
 Current smokers | 20 (15%) | 29 (81%) |
Alcohol drinking | ||
 Never drinkers | 41 (50%) | 8 (25%) |
 Former drinkers | 5 (6%) | 3 (9%) |
 Current drinkers | 36 (44%) | 21 (66%) |
Biopsy localization | ||
 Middle third | 88 (100%) |  |
Tumor localization | ||
 Upper third |  | 2 (3%) |
 Upper-middle thirds |  | 4 (6%) |
 Middle third |  | 33 (52%) |
 Middle-lower thirds |  | 9 (14%) |
 Lower third |  | 15 (24%) |
Tumor differentiation | ||
 in situ |  | 1 (2%) |
 Well |  | 0 (0%) |
 Moderate |  | 49 (79%) |
 Poor |  | 12 (19%) |
T (TNM) | Â | Â |
 Ti |  | 1 (2%) |
 T1 |  | 8 (14%) |
 T2 |  | 13 (22%) |
 T3 |  | 28 (47%) |
 T4 |  | 9 (15%) |
N (TNM) | Â | Â |
 N0 |  | 26 (52%) |
 N1 |  | 24 (48%) |
M (TNM) | Â | Â |
 M0 |  | 26 (76%) |
 M1 |  | 8 (24%) |
Tumor stage | Â | Â |
 0 |  | 1 (3%) |
 I |  | 3 (9%) |
 II |  | 7 (20%) |
 III |  | 16 (46%) |
 IV |  | 8 (23%) |