Table 4.
Univariate and multivariate analyses of local control (LC) and overall survival (OS) in patients with locoregionally recurrent, metastatic, or secondary lung tumors re‐irradiated with carbon‐ion radiotherapy
| Factor | Patients (n) | LC | OS | ||||
|---|---|---|---|---|---|---|---|
| Univariate analysis | Multivariate analysis | Univariate analysis | Multivariate analysis | ||||
| P‐value | HR | P‐value | P‐value | HR | P‐value | ||
| Sex | .026a | 2.862 | .008a | .049a | 1.762 | .091 | |
| Male | 64 | ||||||
| Female | 31 | ||||||
| Age at re‐irradiation, years | .777 | – | – | .530 | – | – | |
| ≥75 | 46 | ||||||
| <75 | 49 | ||||||
| Smoking status | .684 | – | – | .293 | – | – | |
| Smoker/ex‐smoker | 42 | ||||||
| Non‐smoker | 49 | ||||||
| Pulmonary emphysema | .071 | – | – | .484 | – | – | |
| Y | 17 | ||||||
| N | 78 | ||||||
| Interstitial pneumonia | .862 | – | – | .613 | – | – | |
| Y | 7 | ||||||
| N | 88 | ||||||
| Initial disease status | .229 | – | – | .363 | – | – | |
| Primary lung cancer | 73 | ||||||
| Metastatic lung cancer | 22 | ||||||
| Interval between initial irradiation and re‐irradiation, months | .046a | 2.147 | .048a | .665 | – | – | |
| <24 | 62 | ||||||
| ≥24 | 33 | ||||||
| Site of failure at re‐irradiation | .681 | – | – | .510 | – | – | |
| In‐field | 70 | ||||||
| Marginal zone | 24 | ||||||
| Tumor location at re‐irradiation | .478 | – | – | .451 | – | – | |
| Central | 17 | ||||||
| Peripheral | 78 | ||||||
| Re‐irradiation dose, Gy (RBE) | .317 | – | – | .358 | – | – | |
| ≤66.0 | 50 | ||||||
| >66.0 | 45 | ||||||
| CTV for re‐irradiation, mL | .095 | – | – | .001a | 2.804 | .001a | |
| <80.0 | 48 | ||||||
| ≥80.0 | 46 | ||||||
–, Not evaluated; CTV, clinical target volume; HR, hazard ratio; N, no; RBE, relative biological effectiveness; Y, yes.
a
P < .05.