Long-Term Evaluation and Normal Tissue Complication Probability (NTCP) Models for Predicting Radiation-Induced Optic Neuropathy after Intensity-Modulated Radiation Therapy (IMRT) for Nasopharyngeal Carcinoma: A Large Retrospective Study in China

Table 1

Baseline characteristics.

Baseline patient factor or risk factor		RION (%) n = 51	Non-RION (%) n = 3,611	☼ P value
Age (years) Median (min∼max)		50 (16∼73)	44 (7∼81)	0.120
Gender	Female	18 (35.3)	914 (25.3)	0.104
	Male	33 (64.7)	2,697 (74.7)
Diabetes mellitus	Yes	3 (5.9)	164 (4.5)	0.649
	No	48 (94.1)	3,447 (95.5)
Hypertension	Yes	5 (9.8)	186 (5.2)	0.138
	No	46 (90.2)	3,425 (94.8)
Alcohol consumption	Yes	10 (19.6)	628 (17.4)	0.679
	No	41 (80.4)	2,983 (82.6)
Smoking	Yes	18 (35.3)	1,209(33.5)	0.785
	No	33 (64.7)	2,402 (66.5)
Tumor localization	Chiasm/midline	38 (74.5)	2,793 (77.3)	0.839
	Left optic nerve	7 (13.7)	403 (11.2)
	Right optic nerve	6 (11.8)	415 (11.5)
T stage (AJCC, 8th ed.)	T1-2	2 (3.9)	1,513 (41.9)	<0.001
	T3	16 (31.4)	1,564 (43.3)
	T4	33( 64.7)	534 (14.8)
Stage (AJCC, 8th ed.)	I-II	2 (3.9)	1,054 (29.2)	<0.001
	III	13 (25.5)	1,648 (45.6)
	IVA	36 (70.6)	909 (25.2)
EBV DNA before treatment	≥2,000	30 (58.9)	1,578 (44.3)
(Copy/ml)	<2,000	21 (41.2)	1,983 (55.7)	0.019
☆Treatment	RT alone	4 (7.8)	484 (13.4)	0.005
	IC + CC group	37 (72.5)	1,727 (47.8)
	CC group	10 (19.6)	1,400 (38.8)
Best-corrected visual acuity deficiency at the start of therapy		5 (9.8)	20 (0.6)	<0.001
Tumor infiltration/compression of the chiasm/optic nerves		5 (9.8)	14 (0.4)	<0.001
♯Any other factors affecting best-corrected visual acuity eye diseases		0	6 (0.2)	<0.001

☆The treatment was a combination of radiotherapy and chemotherapy, RT = radiation therapy, IC = induction chemotherapy, CC = concurrent chemotherapy, AC= adjuvant chemotherapy; IC + CC group (IC + CC=1,229, IC + CC + AC= 61, IC + CC + target = 157, IC + CC + AC + target = 3, IC = 285, IC + AC = 16, IC + target = 13); CC group (CC= 1,250, CC + AC = 71, CC + target = 89). Note that some visual acuity-deficient patients at the start of therapy were related to tumors but unaffected for the best-corrected visual acuity in one eye (ocular motility disorder = 9, diplopia = 48, ptosis = 6, other = 4, and multiple symptoms = 16); only tumor infiltration/compression of the optic nerves/chiasm will cause deterioration of the BCVA grade in one eye in our study. ♯Any other affects the BCVA eye diseases at the start of therapy (ocular trauma = 1, retinal disease = 4, and cataracts = 1). ☼P-values were calculated using the chi-square test or independent t-test if indicated. Abbreviations: EBV = Epstein-Barr virus; BCVA = best-corrected visual acuity.