The QUANTEC criteria for parotid gland dose and their efficacy to prevent moderate to severe patient-rated xerostomia

Figures & data

Table I. Patient characteristics.

Patient characteristics		Number	%
Sex	Male	227	74
	Female	80	26
Age	≤ 65	204	66
	> 65	103	34
Chemotherapy	Radiotherapy alone	207	67
	Concomitant chemoradiotherapy	89	29
	Concomitant Cetuximab	11	4
Tumour classification	T0	9	3
	T1	40	13
	T2	129	42
	T3	70	23
	T4	59	19
Node classification	positive	142	46
	negative	165	54
Site	Oropharynx/oral cavity	107	35
	Larynx	150	49
	Hypopharynx	28	9
	Nasopharynx/paranasal sinuses	14	5
	Miscellaneous	8	2
Treatment technique	3D-CRT	171	56
	IMRT	136	44

Figure 1. Patient-rated moderate-to-severe xerostomia stratified by risk group (EORTC QLQ-HN35). The p-values refer to the chi-square test, to test for significant differences between high and low risk patients. *p-value > 0.05, **p-value< 0.05, ^†p-value NS.

Table II. Differences in baseline characteristics of the IMRT treated patients classified as low risk versus IMRT treated patients classified as high risk.

		LOW RISK		HIGH RISK
Characteristics		n	%	n	%	P-value	DF
T-classification	T0-T2	25	44%	32	56%	p = 0.029	1
	T3-T4	19	24%	60	76%
N-classification	N0	27	57%	20	43%	p < 0.001	1
	N-plus	17	19%	72	81%
Tumour location	Oropharynx/oral cavity	11	18%	49	82%	p = 0.002	4
	Larynx	24	50%	24	50%
	Hypopharynx	6	35%	11	65%
	Nasopharynx/paranasal sinus	0	0%	8	100%
	Miscelaneous	3	100%	0	0%
Bilateral neck iradiation	No	6	100%	0	0%	p < 0.001	1
	Yes	38	29%	92	70%

Table III. Odds ratios (OR) for potential risk factors in the development of patient-rated xerostomia for patients completed a follow up of 24 months after treatment.

	6 months after treatment			12 months after treatment			18 months after treatment			24 months after treatment
Risk factor	OR	95% CI	P-value	OR	95% CI	P-value	OR	95% CI	P-value	OR	95% CI	P-value
Quantec criteria (met vs. not met)	6.82	(2.82–16.48)	< 0.1	7.31	(2.80–19.09)	< 0.01	6.79	(2.59–17.76)	< 0.01	7.31	(2.87–18.62)	< 0.01
Age (years)	1.05	(1.01–1.09)	0.02	1.07	(1.02–1.12)	< 0.01	1.04	(1.00–1.08)	0.08	1.05	(1.01–1.10)	0.01
Baseline xerostomia score (none vs. a bit)	4.16	(1.68–10.31)	< 0.01	2.85	(1.17–6.94)	0.02	2.98	(1.26–7.06)	0.01	3.14	(1.34–7.32)	0.01

Figure 2. Predicted risk for patient-rated moderate-to-severe xerostomia (EORTC QLQ-HN35) at 6, 12, 18 and 24 months after for different categories; QUANTEC criteria (met vs not met) and baseline xerostomia (none vs minor) as function of increasing age. All curves are based on a multivariate logistic regression analysis for 132 patients with a complete follow up of 24 months.

Figure 3. Percentage of recovery of moderate-to-severe xerostomia as a function of age, stratified by the 4 risk group categories shown in Figure 1. The results are based on multivariate logistic regression analysis using the data of 132 patients with a complete dataset at all time points. The curves indicate the estimated percentages of patients with moderate to severe xerostomia 6 months after completion of treatment that will have been recovered at 24 months. Younger patients show higher percentages of recovery than elderly patients. Patients in whom the QUANTEC criteria were met show higher percentages of recovery than in whom they were not met.