Background
Methods
Study population
The diagnosis of xerostomia
Data collection
Definition of variables
Radiotherapy technique
Chemotherapy
Statistical analysis
Results
The baseline data of characteristics of all participants
Variable | Total (n = 365) | Group | Statistical magnitude | P | |
---|---|---|---|---|---|
Training set (n = 255) | Testing set (n = 110) | ||||
Age receiving radiotherapy, Mean ± SD | 47.69 ± 11.01 | 47.97 ± 10.83 | 47.03 ± 11.44 | t = − 0.750 | 0.452 |
Gender, n (%) | χ2 = 0.089 | 0.765 | |||
Female | 99 (27.12) | 68 (26.67) | 31 (28.18) | ||
Male | 266 (72.88) | 187 (73.33) | 79 (71.82) | ||
History of drinking, n (%) | χ2 = 3.079 | 0.079 | |||
No | 322 (88.22) | 220 (86.27) | 102 (92.73) | ||
Yes | 43 (11.78) | 35 (13.73) | 8 (7.27) | ||
History of smoking, n (%) | χ2 = 4.120 | 0.042 | |||
No | 273 (74.79) | 183 (71.76) | 90 (81.82) | ||
Yes | 92 (25.21) | 72 (28.24) | 20 (18.18) | ||
History of surgery, n (%) | χ2 = 0.213 | 0.644 | |||
No | 307 (84.11) | 213 (83.53) | 94 (85.45) | ||
Yes | 58 (15.89) | 42 (16.47) | 16 (14.55) | ||
History of hypertension, n (%) | χ2 = 0.194 | 0.660 | |||
No | 329 (90.14) | 231 (90.59) | 98 (89.09) | ||
Yes | 36 (9.86) | 24 (9.41) | 12 (10.91) | ||
History of diabetes, n (%) | – | 1.000 | |||
No | 359 (98.36) | 251 (98.43) | 108 (98.18) | ||
Yes | 6 (1.64) | 4 (1.57) | 2 (1.82) | ||
T Stage, n (%) | χ2 = 1.056 | 0.788 | |||
T1 | 75 (20.55) | 50 (19.61) | 25 (22.73) | ||
T2 | 72
(19.73) | 53 (20.78) | 19 (17.27) | ||
T3 | 163 (44.66) | 115 (45.10) | 48 (43.64) | ||
T4 | 55 (15.07) | 37 (14.51) | 18 (16.36) | ||
N Stage, n (%) | χ2 = 2.391 | 0.495 | |||
N0 | 35 (9.59) | 23 (9.02) | 12 (10.91) | ||
N1 | 147 (40.27) | 105 (41.18) | 42 (38.18) | ||
N2 | 153 (41.92) | 103 (40.39) | 50 (45.45) | ||
N3 | 30 (8.22) | 24 (9.41) | 6 (5.45) | ||
Pathological type, n (%) | χ2 = 1.056 | 0.304 | |||
A differentiated non-keratinic carcinoma | 24 (6.58) | 19 (7.45) | 5 (4.55) | ||
An undifferentiated nonkeratinic carcinoma | 341 (93.42) | 236 (92.55) | 105 (95.45) | ||
Radiotherapy fraction, n (%) | χ2 = 0.731 | 0.393 | |||
≤ 30 | 237 (64.93) | 162 (63.53) | 75 (68.18) | ||
> 30 | 128 (35.07) | 93 (36.47) | 35 (31.82) | ||
Dose at 50% of the left parotid volume (Gy), Mean ± SD | 25.45 ± 7.26 | 25.56 ± 7.21 | 25.21 ± 7.41 | t = − 0.41 | 0.681 |
Dose at 50% of the right parotid volume (Gy), Mean ± SD | 25.81 ± 7.72 | 26.15 ± 8.11 | 25.03 ± 6.69 | t = − 1.37 | 0.171 |
Mean dose to left parotid gland (Gy), Mean ± SD | 30.99 ± 5.66 | 31.13 ± 5.68 | 30.69 ± 5.65 | t = − 0.68 | 0.495 |
Mean dose to right parotid gland (Gy), Mean ± SD | 31.08 ± 6.08 | 31.38 ± 6.38 | 30.39 ± 5.26 | t = − 1.53 | 0.127 |
Mean dose to oral cavity mean dose (Gy), Mean ± SD | 32.65 ± 4.68 | 32.67 ± 4.71 | 32.59 ± 4.65 | t = − 0.150 | 0.880 |
Total radiotherapy dose (Gy), n (%) | χ2 = 0.452 | 0.501 | |||
≤ 70GY | 277 (75.89) | 191 (74.90) | 86 (78.18) | ||
> 70GY | 88 (24.11) | 64 (25.10) | 24 (21.82) | ||
Mode of radiotherapy-NDP, n (%) | χ2 = 0.428 | 0.513 | |||
No | 173 (47.40) | 118 (46.27) | 55 (50.00) | ||
Yes | 192 (52.60) | 137 (53.73) | 55 (50.00) | ||
Mode of radiotherapy-DDP, n (%) | χ2 = 0.782 | 0.377 | |||
No | 286 (78.36) | 203 (79.61) | 83 (75.45) | ||
Yes | 79 (21.64) | 52 (20.39) | 27 (24.55) | ||
Mode of radiotherapy-Others, n (%) | χ2 = 0.000 | 0.989 | |||
No | 345 (94.52) | 241 (94.51) | 104 (94.55) | ||
Yes | 20 (5.48) | 14 (5.49) | 6 (5.45) | ||
Course of induction chemotherapy, M (Q1, Q3) | 2.00 (2.00, 3.00) | 2.00 (2.00, 3.00) | 2.00 (2.00, 3.00) | Z = 0.040 | 0.968 |
Concomitant chemoradiotherapy, n (%) | χ2 = 0.049 | 0.824 | |||
No | 77 (21.10) | 53 (20.78) | 24 (21.82) | ||
Yes | 288 (78.90) | 202 (79.22) | 86 (78.18) | ||
Induction chemotherapy, n (%) | χ2 = 0.000 | 0.986 | |||
No | 30 (8.22) | 21 (8.24) | 9 (8.18) | ||
Yes | 335 (91.78) | 234 (91.76) | 101 (91.82) | ||
The regimens of induction chemotherapy, n (%) | χ2 = 2.252 | 0.895 | |||
DP | 111 (30.41) | 79 (30.98) | 32 (29.09) | ||
DPF | 55 (15.07) | 35 (13.73) | 20 (18.18) | ||
GP | 59 (16.16) | 43 (16.86) | 16 (14.55) | ||
None | 30 (8.22) | 21 (8.24) | 9 (8.18) | ||
Others | 4 (1.10) | 2 (0.78) | 2 (1.82) | ||
TP | 65 (17.81) | 47 (18.43) | 18 (16.36) | ||
TPF | 41 (11.23) | 28 (10.98) | 13 (11.82) | ||
Xerostomia, n (%) | χ2 = 1.990 | 0.574 | |||
Grade 0 | 84 (23.01) | 63 (24.71) | 21 (19.09) | ||
Grade 1 | 142 (38.90) | 94 (36.86) | 48 (43.64) | ||
Grade 2 | 108 (29.59) | 76 (29.80) | 32 (29.09) | ||
Grade 3 | 31 (8.49) | 22 (8.63) | 9
(8.18) |
The equilibrium test of training set and testing set
Construction and validation of the RF, DTC and XGB models for xerostomia via LASSO regression
The predictive performance of respective models
Sensitivity (95%CI) | Specificity (95%CI) | PPV (95%CI) | NPV (95%CI) | AUC (95%CI) | Accuracy (95%CI) | |
---|---|---|---|---|---|---|
Training set | ||||||
RF | 1.000 (1.000–1.000) | 0.968 (0.925–1.000) | 0.990 (0.975–1.000) | 1.000 (1.000–1.000) | 0.999 (0.997–1.000) | 0.992 (0.981–1.000) |
XGB | 0.974 (0.951–0.996)* | 0.968 (0.925–1.000) | 0.989 (0.975–1.000) | 0.924 (0.860–0.988)* | 0.995 (0.989–1.000) | 0.973 (0.952–0.993) |
DTC | 0.943 (0.910–0.976) | 0.984 (0.953–1.000) | 0.995 (0.984–1.000) | 0.849 (0.767–0.931)* | 0.963 (0.941–0.986)* | 0.953 (0.927–0.979)* |
Testing set | ||||||
RF | 0.933 (0.880–0.985) | 0.714 (0.521–0.908) | 0.933 (0.880–0.985) | 0.714 (0.521–0.908) | 0.915 (0.860–0.970) | 0.891 (0.833–0.949) |
XGB | 0.820 (0.740–0.900) | 0.714 (0.521–0.908) | 0.924 (0.866–0.982) | 0.484 (0.308–0.660) | 0.834 (0.753–0.916) | 0.800 (0.725–0.875) |
DTC | 0.775 (0.689–0.862)# | 0.762 (0.580–0.944) | 0.932 (0.875–0.990)# | 0.444 (0.282–0.607)# | 0.769 (0.666–0.872)# | 0.773 (0.694–0.851)# |
Prediction of patients with grade 3 xerostomia in those with high risk of xerostomia
Sensitivity (95%CI) | Specificity (95%CI) | PPV (95%CI) | NPV (95%CI) | AUC (95%CI) | Accuracy (95%CI) | |
---|---|---|---|---|---|---|
Training set | ||||||
RF | 0.955 (0.868–1.000) | 0.961 (0.937–0.986) | 0.700 (0.536–0.864) | 0.996 (0.987–1.000) | 0.986 (0.972–1.000) | 0.961 (0.937–0.985) |
XGB | 0.864 (0.720–1.000) | 0.858 (0.814–0.903) | 0.365 (0.235–0.496) | 0.985 (0.969–1.000) | 0.914 (0.844–0.984) | 0.859 (0.816–0.902) |
DTC | 0.500 (0.291–0.709) | 0.991 (0.980–1.000) | 0.846 (0.650–1.000) | 0.955 (0.928–0.981) | 0.746 (0.639–0.853) | 0.949 (0.922–0.976) |
Testing set | ||||||
RF | 0.333 (0.025–0.641) | 0.851 (0.782–0.921) | 0.167 (0.000–0.339) | 0.935 (0.884–0.985) | 0.766 (0.626–0.905) | 0.809 (0.736–0.883) |
XGB | 0.444 (0.120–0.769) | 0.792 (0.713–0.871) | 0.160 (0.016–0.304) | 0.941 (0.891–0.991) | 0.661 (0.478–0.843) | 0.764 (0.684–0.843) |
DTC | 0.222 (0.000–0.494) | 0.980 (0.953–1.000) | 0.500 (0.010–0.990) | 0.934 (0.887–0.981) | 0.601 (0.457–0.746) | 0.918 (0.867–0.969) |