Table 4.

Clinical and dosimetric factors associated with symptoms after CIRT

	no grade change (n = 24)	grade progression (n = 5)	p-value
Clinical factors
Age (yr), median (range)	72.0 (62–90)	76.0 (71–86)	0.224
Performance Status (0/1/2)	13/9/2	1/4/0	0.330
Severity of ILD (JRS) (1/2/3/4)	9/7/4/4	0/3/2/0	0.434
mMRC scale (1/2/3/4/5)	0/9/6/5/4	0/2/0/3/0	0.952
Tumor location (U/L)	11/13	3/2	1.000
Tumor size (mm), median (range)	34.0 (17–58)	31.0 (22–63)	0.544
serum KL-6, median (range)	880.5 (325–2410)	544.0 (466–1199)	0.260
serum SP-D, median (range)	152.0 (60–502)	105.0 (31–140)	0.036
Respiratory function, median (range)
%VC	90.7 (43.5–130.4)	86.7 (64.9–107.3)	0745
%FVC	81.8 (37.9–117.6)	82.7 (52.8–98.7)	0.820
FEV1.0 (L)	2.0 (1.13–2.92)	2.0 (1.47–2.96)	1.000
FEV1.0/VC (%)	80.7 (54.0–91.2)	78.6 (72.7–99.7)	0.696
%DLco	50.7 (15.5–92.2)	70.7 (39–235.5)	0.474
Not evaluated	3	0
Dose-volume metrics, median (range)
PTV (mL)	82.9 (34.6–345.9)	88.1 (52.3–1319.8)	0.507
Total dose (Gy[RBE]),	52.8 (46–72)	50.0 (50–72)	0.5745
Dosimetric factors of the lung (%), median (range)
V5	8.7 (3.0–20.6)	14.2 (10.9–34.8)	0.026
V10	7.6 (2.6–18.3)	11.9 (8.4–32.8)	0.033
V15	5.6 (2.2–13.6)	8.0 (7.1–27.1)	0.074
V20	5.0 (3.0–20.6)	7.3 (6.2–18.0)	0.069
V25	4.2 (1.8–11.0)	5.4 (3.3–16.8)	0.237
V30	3.7 (1.5–9.0)	4.9 (2.8–15.9)	0.286
V35	3.4 (1.4–8.5)	4.4 (2.5–5.0)	0.260
V40	3.1 (1.3–8.0)	4.0 (2.2–14.0)	0.260
Mean Lung Dose (Gy[RBE])	2.8 (1.0–6.4)	3.8 (3.0–12.2)	0.075

Abbreviations: CIRT carbon ion radiotherapy, ILD interstitial lung disease, JRS Japanese Respiratory Society, mMRC scale the modified Medical Research Council scale, KL-6 Krebs von den Lungen-6, SP-D surfactant protein D, VC vital capacity, FVC forced vital capacity, FEV1.0 Forced Expiratory Volume in one second, DLco diffusion capacity of the lung, PTV planning target volume, RBE relative biological effectiveness