Table 5.
Comparison of the median survival time among prognostic predictors on univariate analyses.
| Characteristics | PFS | OS | ||
|---|---|---|---|---|
| Median for survival time | P-value | Median for survival time | P-value | |
| Tumor grading | <0.001 | <0.001 | ||
| Grade I–II | 86.5 | Not reached | ||
| Conventional grade III | 26 | 96 | ||
| HGT | 10 | 50 | ||
| PNI | 0.004 | – | ||
| Negative | Not reached | – | ||
| Positive | 52 | – | ||
| Margin status | – | 0.049 | ||
| ≥1 mm | – | cannot be calculated* | ||
| <1 mm | – | cannot be calculated* | ||
| T stage | 0.004 | – | ||
| 1–2 | 86.5 | – | ||
| 3 | 75.5 | – | ||
| 4 | 26 | – | ||
| Stage groups | 0.015 | 0.07 | ||
| I–II | 86.5 | Not reached | ||
| III | 66 | Not reached | ||
| IV | 36 | 80 | ||
| PORT | 0.013 | 0.028 | ||
| Yes | 86.5 | Not reached | ||
| No | 36 | 77 | ||
PFS, progression-free survival; OS, overall survival; HGT, high-grade transformation; PNI, perineural invasion; PORT, postoperative radiotherapy. *All of the patients with a surgical margin ≥1 mm survived, and all of the deaths occurred in patients with a surgical margin <1 mm; thus, the median overall survival time cannot be calculated.