Toxicity of dose-escalated, hypofractionated helical tomotherapy for inoperable thoracic esophageal squamous cell carcinoma

Table 1 Baseline patient and tumor characteristics

Characteristics	Median (range)	n	%
Sex
Man		41	87.2
Woman		6	12.8
Age, years,	61 (36-86)
Location of tumor
Upper		11	23.4
Middle		17	36.2
Lower		19	40.4
Tumor classification
T3		18	38.3
T4A		7	14.9
T4B		22	46.8
Lymph node status
N0		2	4.3
N1		24	51.1
N2		21	44.7
Disease stage
IIIa		5	10.6
IIIb		13	27.7
IIIc		29	61.7
TP chemotherapy
0		18	38.3
1		4	8.5
2		12	25.5
4		13	27.7

TP: Docetaxel + cisplatin.

Table 2 Summary of dose, fraction and IV grade esophageal toxicity

Dose level (Gy per fraction)	Number of fractions	BED (α/β), 10	EQD2 (α/β), 10	EQD2 (α/β), 15	EQD2 (α/β), 3	Number of patients	Toxicity IV grade	Time, months
3.6	15	73.44	61.20	59.08	71.28	1.00
3.5	20	94.50	78.75	76.18	91.00	1.00
3.3	20	87.78	73.15	71.05	83.16	1.00
3.2	20	84.48	70.40	68.52	79.36	3.00	B	5
3	25	97.50	81.25	79.41	90.00	1.00	B	6
3	23	89.70	74.75	73.06	82.80	1.00
3	22	85.80	71.50	69.88	79.20	1.00
3	20	78.00	65.00	63.53	72.00	2.00	A	6
2.8	27	96.77	80.64	79.16	87.70	1.00	A	5
2.8	20	71.68	59.73	58.64	64.96	1.00
2.7	27	92.58	77.15	75.90	83.11	1.00	B	3
2.7	25	85.73	71.44	70.28	76.95	1.00
2.5	27	84.38	70.31	69.49	74.25	2.00	a: A; b: A	a: at 4th RT; b: 10
2.5	25	78.13	65.10	64.34	68.75	2.00
2.5	20	62.50	52.08	51.47	55.00	1.00
2.5	18	56.25	46.88	46.32	49.50	1.00
2.4	28	83.33	69.44	68.78	72.58	1.00
2.4	26	77.38	64.48	63.87	67.39	1.00
2.4	25	74.40	62.00	61.41	64.80	3.00
2.4	20	59.52	49.60	49.13	51.84	1.00	B	2
2.3	28	79.21	66.01	65.54	68.26	1.00
2.3	27	76.38	63.65	63.20	65.83	1.00
2.3	26	73.55	61.30	60.86	63.39	2.00
2.3	25	70.73	58.94	58.51	60.95	2.00	B	7
2.3	23	65.07	54.22	53.83	56.07	1.00
2.2	28	75.15	62.63	62.32	64.06	2.00
2.2	25	67.10	55.92	55.65	57.20	2.00
2	30	72.00	60.00	60.00	60.00	2.00
2	27	64.80	54.00	54.00	54.00	2.00	B	7
2	25	60.00	50.00	50.00	50.00	5.00

Biologic effective dose at 2Gy per fraction = nd [1 + d/(α/β)]; Equivalent dose at 2Gy per fraction = nd (α/β + d)/(α/β + 2). “A” refers to tracheo-esophageal fistulas; “B” refers to bleeding related to aorto-esophageal fistulalization. BED: Biologic effective dose; EQD: Equivalent dose; RT: Radiation

Table 3 Ordinal logistic regression of esophageal toxicity

	Estimate	SE	Wald	P value	95%CI
Dose level (Gy per fraction)	-0.96	1.14	0.70	0.40	-3.20 to 1.28
EQD2 (α/β = 10)	0.17	0.06	6.99	0.01	0.04 to 0.29
Tumor classification	-0.12	0.37	0.11	0.74	-0.86 to 0.61

EQD₂: Equivalent dose at 2Gy per fraction.