Risk structures for radiation-induced trismus in head and neck cancer

Figures & data

Table 1. Mean absorbed doses, volumes, and standard deviations for potential trismus risk structures.

Risk structures		Ipsilateral	Contralateral	Bilateral
		Mean dose ± SD (Gy)	Mean dose ± SD (Gy)	Mean dose ± SD (Gy)
	n = patients analyzed	Volume ± SD (cm^3)	Volume ± SD (cm^3)	Volume ± SD (cm^3)
Masseter	181	41.5 ± 11.0	29.8 ± 9.9	35.7 ± 9.1
		17.9 ± 5.8	15.9 ± 5.1	33.9 ± 10.9
Lateral pterygoid	210	32.2 ± 21.0	20.9 ± 16.8	26.5 ± 18.1
		5.7 ± 1.5	4.8 ± 1.4	10.6 ± 2.8
Medial pterygoid	123	59.9 ± 10.4	46.5 ± 13.7	53.2 ± 10.8
		8.6 ± 2.1	7.5 ± 2.1	16.1 ± 4.1
Temporalis	210	7.2 ± 7.3	4.9 ± 5.3	6.1 ± 6.2
		19.7 ± 5.8	17.3 ± 5.2	37.1 ± 10.9
TM joint	216	21.6 ± 19.0	12.5 ± 12.6	17.1 ± 15.0
		2.1 ± 0.7	1.6 ± 0.8	3.7 ± 1.4
Ganglion PPT	216	13.2 ± 18.8	10.3 ± 16.0	11.8 ± 17.2
		0.4 ± 0.2	0.3 ± 0.2	0.6 ± 0.3
Soft palate	123			58.9 ± 14.2
				1.9 ± 1.0

Risk structures receiving substantial dose from brachytherapy (more than a maximum absorbed doses of 3.0 Gy or more than mean absorbed doses of 2.0 Gy) were excluded from analysis of that specific structure.

Figure 1. The relationships between dose to the masseter muscle and trismus (A) and the temporo-mandibular joint and trismus (B). Trismus according to MIO (maximal interincisal opening) ≤35 mm, GTQ (Gothenburg Trismus Questionnaire) answering categories 3–5, and EORTC QLQ-HN35 (European Organization for Research and Treatment of Cancer Head and Neck Questionnaire) answering categories 3–4.

Table 2. Logistic regression and ROC analysis of risk structure doses as predictors for trismus in head and neck cancer patients treated with radiotherapy (bilateral mean dose).

		MIO		GTQ		EORTC QLQ-HN35
Risk structure	Logistic regression analysis	p-Value	AUC	p-Value	AUC	p-Value	AUC
Masseter	Univariable	<0.01	0.69	<0.01	0.71	<0.01	0.63
	Multivariable	<0.01	0.76	<0.01	0.78	<0.01	0.72
Lateral pterygoid	Univariable	<0.01	0.69	<0.01	0.64	0.09	0.59
	Multivariable	<0.01	0.74	<0.01	0.73	0.11	0.61
Medial pterygoid	Univariable	<0.01	0.67	0.15	0.58	0.16	0.56
	Multivariable	0.04	0.75	0.06	0.73	0.07	0.69
Temporal	Univariable	<0.01	0.68	0.02	0.64	0.36	0.57
	Multivariable	0.07	0.69	0.02	0.70	0.68	0.60
TM joint	Univariable	<0.01	0.66	<0.01	0.65	0.02	0.61
	Multivariable	<0.01	0.72	<0.01	0.74	0.03	0.62
Ganglion PPT	Univariable	0.02	0.67	0.18	0.62	0.49	0.55
	Multivariable	0.10	0.69	0.09	0.67	0.91	0.59
Soft palate	Univariable	0.20	0.56	0.69	0.57	0.75	0.50
	Multivariable	0.30	0.72	0.75	0.69	0.70	0.65

ACE-27, Adult Comorbidity Evaluation 27; AUC, area under the ROC-curve; EORTC QLQ HN35, European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Head and Neck 35; GTQ, Gothenburg Trismus Questionnaire; MIO, maximal interincisal opening; ROC, receiver operating characteristics.

For MIO, results from multivariable analysis are adjusted for smoking and height; for GTQ, adjusted for ACE-27, and for EORTC QLQ-HN 35.