Patient- and treatment-related risk factors associated with neck muscle spasm in nasopharyngeal carcinoma patients after intensity-modulated radiotherapy

Table 3 Radiation dose tolerances for the SCM with respect to neck muscle spasm, as determined using ROC curve analysis

	Area under ROC curve	Standard error	P	Lower limit	Upper limit	Cut-off point	Sensitivity	Specificity
V20^a	0.795	0.030	<0.001	0.737	0.853	99.99%	0.920	0.673
V25	0.810	0.029	<0.001	0.752	0.867	99.99%	0.900	0.713
V30	0.815	0.029	<0.001	0.758	0.872	99.94%	0.900	0.709
V35	0.834	0.029	<0.001	0.777	0.892	98.94%	0.920	0.665
V40	0.834	0.029	<0.001	0.777	0.891	97.58%	0.920	0.685
V45	0.826	0.029	<0.001	0.769	0.883	94.72%	0.900	0.689
V50	0.860	0.025	<0.001	0.810	0.910	90.02%	0.900	0.732
V55	0.895	0.023	<0.001	0.849	0.941	65.78%	0.940	0.524
V60	0.934	0.024	<0.001	0.887	0.981	61.92%	0.900	0.953
V65	0.848	0.303	<0.001	0.784	0.912	28.94%	0.680	0.902
V70	0.675	0.046	<0.001	0.584	0.766	0.57%	0.600	0.744

Abbreviations: SCM sternocleidomastoid muscle, ROC receiver operating characteristic, V20 ^a percentage of the sternocleidomastoid muscle volume that received >20 Gy; other dosimetric parameters are reported in a similar manner

ISSN: 1471-2407