Multiple regression analysis of risk factors related to radiation pneumonitis

Table 1 Comparison of general data between the two groups [n (%)]

General information		Control group (n = 141)	Study group (n = 93)	χ2	P
Sex	Male	70 (49.65)	56 (60.22)	2.519	0.112
	Female	71 (50.35)	37 (39.78)
Age (years)	< 60	80 (56.74)	36 (38.71)	7.286	0.007
	≥ 60	61 (43.26)	57 (61.29)
Smoking	Yes	48 (34.04)	39 (41.94)	1.495	0.221
	No	93 (65.96)	54 (58.06)
Tumor type	lung cancer	52 (36.88)	69 (74.19)	36.127	< 0.001
	Mammary cancer	52 (36.88)	21 (22.58)
	Esophageal cancer	37 (26.24)	3 (2.23)
TNM stage	II	43 (30.50)	39 (41.94)	5.065	0.079
	III	54 (38.30)	36 (38.71)
	IV	44 (31.20)	18 (19.35)
History of chemotherapy	Yes	36 (25.53)	57 (61.29)	29.921	< 0.001
	No	105 (74.47)	36 (38.71)
Operation	Yes	47 (33.33)	39 (41.94)	1.784	0.182
	No	94 (66.67)	54 (58.06)

Table 2 Comparison of lung function and radiotherapy parameters between the two groups (mean ± standard deviation)

Group (n)	FEV1 (%)	DLCO (%)	FEV1/FVC (%)	PTV (mL)	MLD (Gy)	Total number of radiation fields	Vdose (%)	NTCP (%)
Control group (n = 141)	76.89 ± 6.25	71.97 ± 10.03	72.19 ± 7.44	28.26 ± 8.31	35.29 ± 6.57	7.07 ± 2.07	24.54 ± 10.33	42.45 ± 3.60
Study group (n = 93)	70.26 ± 7.50	64.19 ± 9.71	64.45 ± 7.20	38.48 ± 8.27	40.71 ± 5.42	8.00 ± 1.71	36.06 ± 9.95	49.29 ± 4.72
t	7.339	5.918	7.940	9.235	6.599	3.731	8.589	12.540
P	< 0.001	< 0.001	< 0.001	< 0.001	< 0.001	< 0.001	< 0.001	< 0.001

FEV1: Forced expiratory volume in the first second; DLCO: Carbon monoxide diffusion volume; FVC: Forced vital capacity; PTV: Planned target area; MLD: Mean lung dose; Vdose: Percentage of lung tissue in total lung volume; NTCP: Normal tissue complications.

Table 3 Logistic regression analysis of risk factors for radiation pneumonitis

Factor	B	S.E.	Wald	P	OR	95%CI
Age	-2.232	0.842	7.028	0.008	0.11	0.02-0.48
Tumor type (Lung)
Mammary	-3.038	0.938	8.313	0.001	0.05	0.01-0.26
Esophageal	-3.753	1.075	8.313	< 0.001	0.02	0.00-0.16
History of chemotherapy	3.108	0.854	13.259	< 0.001	22.37	4.85-143.77
FEV1	0.292	0.096	9.199	0.002	1.34	1.13-1.65
DLCO	0.410	0.093	19.226	< 0.001	1.51	1.28-1.85
FEV1/FVC ratio	-0.329	0.119	7.656	0.006	0.72	0.59-0.90
PTV	0.477	0.149	10.206	0.001	1.61	1.23-2.22
MLD	-0.217	0.118	3.377	0.066	0.80	0.65-1.03
Total number of radiation fields	-0.905	0.244	13.812	< 0.001	0.40	0.23-0.62
Vdose	-0.127	0.086	2.189	0.139	0.88	0.74-1.04
NTCP	1.206	0.211	32.636	< 0.001	3.34	2.33-5.41

FEV1: Forced expiratory volume in the first second; DLCO: Carbon monoxide diffusion volume; FVC: Forced vital capacity; PTV: Planned target area; MLD: Mean lung dose; Vdose: Percentage of lung tissue in total lung volume; NTCP: Normal tissue complications.