J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website https://jocmr.elmerjournals.com

Original Article

Volume 18, Number 9, September 2026, pages 623-631

Radiation-Induced Xerostomia in Patients With Head and Neck Cancer Treated With Comprehensive Salivary Gland-Sparing Helical Tomotherapy Technique Based on a Back Propagation Artificial Neural Network

↓ Figure 1. Illustration of target volume and salivary glands (fixed four layers). Panels a–d display different anatomical structures of the head and neck across four fixed layers, with each panel presenting a different view of the tumor volume, target volumes, and key salivary glands. Red line: GTVnx; brown line: GTVnd; pink line: CTV1; orange line: oral cavity; blue and green blocks: parotid glands; bright red and bright blue blocks: submandibular glands; yellow and faint yellow blocks: tubarial glands. GTVnx: gross tumor volume of nasopharynx; GTVnd: gross tumor volume of lymph nodal; CTV1: clinical target volume 1.

↓ Figure 2. Topology diagrams of the BPANN prediction models at (a) 1 year and (b) 2 years post-radiotherapy. The input layer consists of the selected predictors including age, gender, tumor type, and bilateral radiation doses of parotid, submandibular, oral cavity and tubarial glands; the middle hidden layers represent the multilayer neural network architecture capturing nonlinear interactions among variables; the output layer generates three categories of predicted xerostomia risk (no xerostomia, mild xerostomia, moderate/severe xerostomia).Model training metrics are listed as follows: (a) 1-year prediction model: error = 0.37836, training steps = 85,429; (b) 2-year prediction model: error = 0.175809, training steps = 187,816. BPANN: back propagation artificial neural network.

↓ Figure 3. ROC curves of the BPANN prediction models for xerostomia risk at (a) 1 year and (b) 2 years post-radiotherapy. Blue curves represent the discrimination performance for patients without xerostomia, green curves for mild xerostomia, and red curves for moderate/severe xerostomia, with corresponding AUC values marked on each curve. AUC results: (a) 1-year model: no xerostomia = 0.8835, mild xerostomia = 0.9474, moderate/severe xerostomia = 0.9650; (b) 2-year model: no xerostomia = 0.9417, mild xerostomia = 0.9000, moderate/severe xerostomia = 0.8901. BPANN: back propagation artificial neural network; ROC: receiver operating characteristic.

↓ **Table 1.** Patient Characteristics (N = 222)
Characteristics	Number of patients (%)
XQ score categories: 0–5, no xerostomia; 6–10, mild xerostomia; 11–20, moderate xerostomia; and 21–30, severe xerostomia. XQ: xerostomia questionnaire; PG: parotid gland; SMG: submandibular gland; OC: accessory salivary glands in the oral cavity; TG: tubarial gland; R: right; L: left.
Age (years)
Mean	49
Median (range)	52 (10–83)
Gender
Male	164 (73.87)
Female	58 (26.13)
Tumor type
Nasopharyngeal cancer	181 (81.53)
Oral cavity and oropharyngeal cancer	12 (5.41)
Hypopharyngeal and laryngeal cancer	19 (8.56)
Nasal cavity and paranasal sinuses cancer	10 (4.50)
PG-R/L (Gy)
Mean	29.86/29.75
Median (ranged)	29.52/29.59 (19.45–62.86/18.28–47.79)
SMG-R/L (Gy)
Mean	42.78/45.04
Median (range)	33.49/39.97 (21.37–71.63/22.38–69.56)
OC (Gy)
Mean	32.39
Median (range)	31.91 (19.15–54.10)
TG-R/L (Gy)
Mean	62.84/63.18
Median (range)	67.54/67.64 (9.46–71.73/9.41–71.74)
XQ score, 1 year
Mean	8.74
Median (range)	8.00 (0–23)
No xerostomia	50 (22.52)
Mild xerostomia	105 (47.30)
Moderate/severe xerostomia	67 (30.18)
XQ score, 2 years
Mean	4.44
Median (range)	3.00 (0–24)
No xerostomia	155 (69.82)
Mild xerostomia	46 (20.72)
Moderate/severe xerostomia	21 (9.46)

↓ Table 1. Patient Characteristics (N = 222)

Characteristics

Number of patients (%)

XQ score categories: 0–5, no xerostomia; 6–10, mild xerostomia; 11–20, moderate xerostomia; and 21–30, severe xerostomia. XQ: xerostomia questionnaire; PG: parotid gland; SMG: submandibular gland; OC: accessory salivary glands in the oral cavity; TG: tubarial gland; R: right; L: left.

Age (years)

Mean

Median (range)

52 (10–83)

Gender

Male

164 (73.87)

Female

58 (26.13)

Tumor type

Nasopharyngeal cancer

181 (81.53)

Oral cavity and oropharyngeal cancer

12 (5.41)

Hypopharyngeal and laryngeal cancer

19 (8.56)

Nasal cavity and paranasal sinuses cancer

10 (4.50)

PG-R/L (Gy)

Mean

29.86/29.75

Median (ranged)

29.52/29.59 (19.45–62.86/18.28–47.79)

SMG-R/L (Gy)

Mean

42.78/45.04

Median (range)

33.49/39.97 (21.37–71.63/22.38–69.56)

OC (Gy)

Mean

32.39

Median (range)

31.91 (19.15–54.10)

TG-R/L (Gy)

Mean

62.84/63.18

Median (range)

67.54/67.64 (9.46–71.73/9.41–71.74)

XQ score, 1 year

Mean

8.74

Median (range)

8.00 (0–23)

No xerostomia

50 (22.52)

Mild xerostomia

105 (47.30)

Moderate/severe xerostomia

67 (30.18)

XQ score, 2 years

Mean

4.44

Median (range)

3.00 (0–24)

No xerostomia

155 (69.82)

Mild xerostomia

46 (20.72)

Moderate/severe xerostomia

21 (9.46)

↓ **Table 2.** Spearman’s Rank Correlation Test for Association Between XQ Score and Relevant Characteristics
Variables	XQ score (1 year)	XQ score (2 years)
XQ score categories: 0–5, no xerostomia; 6–10, mild xerostomia; 11–20, moderate xerostomia; 21–30, severe xerostomia. Supplementary subgroup sizes for correlation analysis (full cohort, n = 222): 1-year: no xerostomia = 50, mild = 105, moderate/severe = 67; 2-year: no xerostomia = 155, mild = 46, moderate/severe = 21. XQ: xerostomia questionnaire; PG: parotid gland; SMG: submandibular gland; OC: accessory salivary glands in the oral cavity; TG: tubarial gland; R: right; L: left; Dmean: mean dose.
Gender	0.098	0.144	0.154	0.022
Tumor type	−0.070	0.302	−0.048	0.475
Age	0.180	0.007	0.241	< 0.001
PG-R Dmean	−0.050	0.459	−0.073	0.279
PG-L Dmean	0.063	0.348	−0.010	0.882
SMG-R Dmean	0.093	0.166	0.128	0.037
SMG-L Dmean	0.120	0.075	0.153	0.022
OC Dmean	0.020	0.762	−0.005	0.941
TG-R Dmean	0.021	0.757	−0.052	0.444
TG-L Dmean	0.094	0.163	−0.011	0.873

↓ Table 2. Spearman’s Rank Correlation Test for Association Between XQ Score and Relevant Characteristics

Variables

XQ score (1 year)

XQ score (2 years)

P value

XQ score categories: 0–5, no xerostomia; 6–10, mild xerostomia; 11–20, moderate xerostomia; 21–30, severe xerostomia. Supplementary subgroup sizes for correlation analysis (full cohort, n = 222): 1-year: no xerostomia = 50, mild = 105, moderate/severe = 67; 2-year: no xerostomia = 155, mild = 46, moderate/severe = 21. XQ: xerostomia questionnaire; PG: parotid gland; SMG: submandibular gland; OC: accessory salivary glands in the oral cavity; TG: tubarial gland; R: right; L: left; Dmean: mean dose.

Gender

0.098

0.144

0.154

0.022

Tumor type

−0.070

0.302

−0.048

0.475

Age

0.180

0.007

0.241

< 0.001

PG-R Dmean

−0.050

0.459

−0.073

0.279

PG-L Dmean

0.063

0.348

−0.010

0.882

SMG-R Dmean

0.093

0.166

0.128

0.037

SMG-L Dmean

0.120

0.075

0.153

0.022

OC Dmean

0.020

0.762

−0.005

0.941

TG-R Dmean

0.021

0.757

−0.052

0.444

TG-L Dmean

0.094

0.163

−0.011

0.873

↓ **Table 3.** BPANN Model Predictions for Xerostomia at Different Follow-up Times Post-Radiotherapy
Predicted value	True value
The total test set sample size is 63; true subgroup counts: 1-year true group: no xerostomia = 13, mild = 34, moderate/severe = 16; 2-year true group: no xerostomia = 45, mild = 11, moderate/severe = 7. BPANN: back propagation artificial neural network.
No xerostomia	9	45	1	1	2	2	12	48
Mild xerostomia	3	0	30	10	4	1	37	11
Moderate/severe xerostomia	1	0	3	0	10	4	14	4
Total	13	45	34	11	16	7	63	63

↓ Table 3. BPANN Model Predictions for Xerostomia at Different Follow-up Times Post-Radiotherapy

Predicted value

True value

No xerostomia

Mild xerostomia

Moderate/severe xerostomia

Sum

1 year

2 years

1 year

2 years

1 year

2 years

1 year

2 years

The total test set sample size is 63; true subgroup counts: 1-year true group: no xerostomia = 13, mild = 34, moderate/severe = 16; 2-year true group: no xerostomia = 45, mild = 11, moderate/severe = 7. BPANN: back propagation artificial neural network.

No xerostomia

Mild xerostomia

Moderate/severe xerostomia

Total