Table 4.

Overview of studies on NTCP models for tube feeding dependence.

Reference	Time point, mo	Quality criteria for NTCP models										Level of evidence
		RT technique	Study design	Analysis	No. of patients	No. of events	AUC	Calibration tested	Internal validation	External validation	Individual NTCP estimation possible
Current study	6	Primary 3DCRT and IMRT	Prospective	External validation	867	102	0.87	Yes	Yes	Yes	Yes	1b
Caudell 2010 [21]	12	IMRT	Retrospective	Univariable	83	18		No	No	No	No	4
Sanguineti 2011 [22]	During RT	IMRT	Retrospective	Multivariable	59	22		No	No	No	Yes	4
Wopken 2014 [23]	6	Primary 3DCRT and IMRT	Prospective	Multivariable	355	38	0.88	Yes	Yes	No	Yes	3
Vlacich 2014 [24]	>12	IMRT	Retrospective	Univariable	141	18		No	No	No	No	4
Li 2009 [25]	>6	IMRT	Retrospective	Univariable	39			No	No	No	No	4

Abbreviations: NTCP, Normal Tissue Complication Probability; RT, radiation therapy; AUC, Area Under the Curve; 3DCRT, 3-dimensional conformal radiation therapy; IMRT, intensity-modulated radiation therapy.