Table 2.
Univariate Analysis of Clinical Characteristics Associated With Overall Survival (OS).a
| Univariate | Multivariate | |||
|---|---|---|---|---|
| Characteristic | OS, Median (95% CI), months | P Valueb | Hazard Ratio (95% CI) | P Valuec |
| Gender | ||||
| Male | 20.9 (9.0-32.8) | .286 | – | – |
| Female | 18.3 (14.6-22.0) | – | ||
| Age, years | ||||
| <70 | 25.6 (13.2-32.9) | .066 | – | – |
| ≥70 | 16.7 (12.0-21.3) | – | ||
| ECOG PS | ||||
| 0 | 19.3 (15.5-23.0) | .746 | – | – |
| 1 | 20.9 (-) | – | ||
| Tumor location | ||||
| Head | 18.0 (14.0-22.0) | .122 | – | – |
| Body/tail | 20.9 (18.1-23.7) | – | ||
| Tumor size,b cm | ||||
| <4 | 18.0 (14.2-21.8) | .259 | – | – |
| ≥4 | 20.9 (17.7-24.1) | – | ||
| T classification | ||||
| T3 | 15.7 (4.2-27.2) | .156 | – | – |
| T4 | 19.7 (16.4-23.0) | – | ||
| N classification | ||||
| N0 | 19.3 (15.8-22.8) | .390 | – | – |
| N1 | 25.6 (4.4-46.8) | – | ||
| Pretreatment CA 19-9 level, U/mL | ||||
| ≤37 | 16.7 (8.3-25.0) | .749 | – | – |
| >37 | 19.7 (14.8-24.4) | – | ||
| Induction chemotherapy | ||||
| No | 16.7 (13.5-19.8) | .031 | 1.000 | .040 |
| Yes | 21.6 (-) | 0.317 (0.106-0.949) | ||
| Pre-SIB-PBT CA 19-9 level, U/mL | ||||
| ≤37 | 19.3 (12.6-25.9) | .719 | – | – |
| >37 | 19.7 (15.6-23.8) | – | ||
| Concurrent chemotherapy | ||||
| No | 8.3 (2.9-13.7) | .036 | – | – |
| Yes | 20.9 (16.8-25.1) | – | ||
| Post-SIB-PBT CA 19-9 level, U/mL | ||||
| ≤37 | 19.3 (14.3-24.3) | .541 | – | – |
| >37 | 21.6 (15.8-27.4) | – | ||
| Primary tumor response | ||||
| Responder | 21.2 (19.3-23.1) | .432 | – | – |
| Nonresponder | 16.7 (12.6-20.7) | – | ||
| Post-SIB-PBT surgery | ||||
| No | 18.3 (12.2-21.6) | .139 | – | – |
| Yes | NR (-) | – | ||
| Maintenance chemotherapy | ||||
| No | 15.7 (8.2-23.2) | .044 | – | – |
| Yes | 21.2 (17.4-25.0) | – | ||
Abbreviations:CI, confidence interval; ECOG PS, Eastern Cooperative Oncology Group performance status; CA 19-9, carbohydrate antigen 19-9; NR, not reached; SIB-PBT, simultaneous integrated boost-proton beam therapy.
a Responder denotes complete or partial response and nonresponder denotes stable disease or progressive disease.
b Log-rank test.
c Cox proportional hazards model.