|  | Nitrous Oxide | Nitrogen |  |
---|---|---|---|---|
Factor | Level | N = 97 | N = 107 | P-Value |
Gender | Female | 40 (41) | 39 (37) | 0.48 |
Hospital | AKH | 87 (90) | 94 (88) | 0.68 |
 | SMZ-OST | 10 (10) | 13 (12) |  |
Dukes classification | A | 17 (19) | 16 (16) | 0.96 |
 | B | 27 (30) | 31 (30) |  |
 | C | 33 (36) | 38 (37) |  |
 | D | 14 (15) | 17 (17) |  |
Tumor Grade | G1 | 3 (3) | 5 (5) | 0.68 |
 | G2 | 67 (74) | 75 (72) |  |
 | G3 | 19 (21) | 24 (23) |  |
 | G4 | 1 (1) | 0 (0) |  |
Site | Ascending Colon | 10 (11) | 18 (17) | 0.73 |
 | Sigmoid Colon | 28 (30) | 30 (28) |  |
 | Rectal | 45 (48) | 44 (42) |  |
 | Cecum | 10 (11) | 13 (12) |  |
 | Multiple | 1 (1) | 1 (1) |  |
Dissemination | Yes | 23 (24) | 25 (24) | 0.92 |
Invasion to Adjacent Organs | Yes | 31 (33) | 28 (26) | 0.33 |
Neural Invasion | Yes | 9 (10) | 10 (9) | 0.95 |
Vessel Invasion | Yes | 21 (23) | 27 (26) | 0.63 |
Treatment of Tumor besides surgery | None | 36 (39) | 50 (48) | 0.30 |
 | Chemotherapy | 30 (32) | 30 (29) |  |
 | Radiation | 15 (16) | 9 (9) |  |
 | Both | 12 (13) | 16 (15) |  |
Age (Years) |  | 61 ± 11 | 63 ± 11 | 0.41 |
Number of Nodes examined | Â | 16 [12, 21] | 15 [12, 23] | 0.97 |
Number of involved Nodes | Â | 0 [0, 4] | 1 [0, 3] | 0.88 |
Preoperative CEA | Â | 4.9 [1.7, 13.0] | 3.5 [1.9, 7.5] | 0.70 |
Recurrence-free survival (years) | Â | 3.9 [1.2, 5.4] | 4.4 [1.1, 5.2] | 0.89 |