Table 2 Clinical and dosimetric factors predicting radiation pneumonitis ≥ grade 2 for patients treated with concurrent chemoradiotherapy

Clinical factors

Age, ≥ 65 years

1.136 (0.644–2.004)

0.660

 < 65

ECOG PS before CCRT, ≥ 2

0.421 (0.102–1.744)

0.233

 < 2

ECOG PS before ICI, ≥ 2^†

1.754 (0.360–8.541)

0.487

(Ex-) smoker

1.356 (0.698–2.633)

0.369

Never-smoker

Underlying lung disease

1.162 (0.587–2.300)

0.668

No underlying lung disease

EGFR mutation

1.155 (0.445–2.998)

0.767

Wild type

PFT

FVC, %

0.992 (0.973–1.1012)

0.428

[Continuous]

FEV1, L

0.930 (0.579–1.493)

0.763

[Continuous]

FEV1, %

0.991 (0.977–1.006)

0.255

[Continuous]

DLCO, %

0.995 (0.980–1.010)

0.487

[Continuous]

Clinical stage, ≥ IIIA

1.358 (0.503–3.664)

0.546

Stage II

Tumor location, lower lobe

2.014 (0.951–4.266)

0.067

Tumor at RUL, RML, LUL

Use of ICI

1.802 (1.019–3.186)

0.043

Non-ICI group

Chemotherapy agent during CCRT, Paclitaxel/ Cisplatin

1.498 (0.834–2.690)

0.177

Chemotherapy agent other than Paclitaxel/ Cisplatin

No. of cycle of chemotherapy

0.903 (0.764–1.068)

0.234

[Continuous]

Dosimetric factors

Total dose, > 60 Gy

1.084 (0.615–1.910)

0.782

≤ 60 Gy

PTV volume, ≥ 280 cm³

1.459 (0.815–2.612)

0.204

< 280 cm³

MLD, ≥ 16 Gy

2.299 (1.234–4.284)

0.009

< 16 Gy

V5, ≥ 28%

2.359 (0.880–6.322)

0.088

< 28%

V10, ≥ 23%

1.914 (0.851–4.304)

0.116

< 23%

V20, ≥ 19%

2.898 (1.331–6.309)

0.007

< 19%

V30, ≥ 18%

2.295 (1.297–4.060)

0.004

< 18%

V40, ≥ 14%

2.513 (1.431–4.412)

0.001

< 14%