Table 2.
Analysis of SEER patients in subgroups of examined lymph nodes
| ≤5 lymph nodes | 6–12 lymph nodes | ≥13 lymph nodes | p value | |
|---|---|---|---|---|
| n | 6,789 (46 %) | 4,272 (29 %) | 3,846 (25 %) | |
| Primary site | ||||
| Head | 71.1 % | 82.4 % | 85.6 % | <0.01 |
| Body/tail | 28.9 % | 17.6 % | 14.4 % | |
| Mean tumor size (±SD) | 42.6 (±31.5)a | 37.4 (±23.1)b | 38.4 (±24.1)c | pab, ac<0.01, pbc=0.124 |
| AJCC T stage | ||||
| Tis | 3.2 % | 2.1 % | 1.8 % | <0.01 |
| T1 | 9.2 % | 6.3 % | 5.4 % | |
| T2 | 21.4 % | 17.4 % | 15.1 % | |
| T3 | 51.9 % | 68.4 % | 71.7 % | |
| T4 | 14.3 % | 5.8 % | 6.1 % | |
| AJCC N stage | ||||
| N0 | 55.9 % | 41.9 % | 30.8 % | <0.01 |
| N1 | 44.1 % | 58.1 % | 69.2 % | |
| Regional nodes examined (±SD) | 1.66 (±1.78) | 8.8 (±1.97) | 19.86 (±7.44) | <0.01 |
| Regional nodes positive (±SD) | 0.68 (±0.96) | 1.5 (±1.8) | 2.9 (±0.17) | <0.01 |
| Mean lymph node ratio (±SD) | 0.27 (±0.37) | 0.17 (±0.21) | 0.15 (±0.17) | <0.01 |
| Lymph node ratio | ||||
| No positive nodes | 55.9 % | 41.9 % | 30.8 % | <0.01 |
| <0.2 | 4.2 % | 26.9 % | 40.4 % | |
| 0.2–0.3 | 3.9 % | 9.2 % | 11.8 % | |
| ≥0.3 | 36.0 % | 22.0 % | 17.0 % | |
pab is the p value for the difference between a and b. Similarly for pac and pbc