Table 2.
The dummy features’ contributions to lymphopenia in Testing cohort (total 589 patients), including the mean SHAP value and direction of SHAP in XGboost models and the mean coefficients in Lasso regression across all iterations.
| Feature | XGboost models | Lasso regressions | ||
|---|---|---|---|---|
| SHAP value | direction of SHAP | Coefficients | P value | |
| baseline lymphocytes | 5.226 | -0.964 | -0.902 | <0.001 |
| integral dose of the total body | 4.021 | 0.858 | 0.487 | <0.001 |
| V5 of bilateral lungs | 1.451 | 0.886 | 0.282 | <0.001 |
| V5 of ipsilateral lung | 1.151 | 0.871 | 0.349 | <0.001 |
| baseline white blood cells | 0.990 | -0.838 | -0.069 | 0.106 |
| mean bilateral lungs dose | 0.905 | 0.788 | 0.171 | 0.076 |
| maxim heart dose | 0.783 | 0.187 | 0 | 1 |
| mean heart dose | 0.774 | -0.377 | 0 | 1 |
| baseline hemoglobin | 0.737 | 0.378 | 0.124 | <0.001 |
| baseline platelet | 0.579 | -0.681 | -0.104 | <0.001 |
| baseline monocytes | 0.533 | -0.295 | -0.063 | 0.048 |
| mean ipsilateral lung dose | 0.469 | 0.654 | 0.153 | 0.138 |
| chemotherapy regimens: taxane | 0.420 | -0.672 | -0.334 | <0.001 |
| V20 of ipsilateral lung | 0.383 | 0.308 | 0 | 1 |
| chemotherapy regimens: anthracycline+taxane | 0.368 | 0.714 | 0.238 | <0.001 |
| tumor size | 0.359 | -0.629 | 0 | 1 |
| Ki67 | 0.298 | -0.600 | -0.092 | 0.014 |
| baseline neutrophils | 0.283 | 0.053 | 0.061 | 1 |
| age | 0.254 | -0.282 | 0.016 | 1 |
| without HER2 | 0.160 | 0.470 | 0.290 | <0.001 |
| V20 of bilateral lungs | 0.150 | 0.126 | 0.118 | 1 |
| RT technology: 3D-fields | 0.083 | -0.477 | 0 | 1 |
| RT technology: RapidArc | 0.081 | 0.258 | 0.759 | <0.001 |
| with HER2 | 0.053 | -0.341 | 0 | 1 |
| neoadjuvant chemotherapy | 0.050 | 0.256 | 0.321 | <0.001 |
| HR+/HER2- | 0.045 | 0.321 | 0.159 | 1 |
| electron: 10Gy/5fx | 0.041 | 0.290 | 0.276 | 1 |
| HR+/HER2+ | 0.040 | -0.206 | -0.245 | 0.016 |
| modified stage II | 0.040 | 0.054 | -0.056 | 1 |
| without drinking history | 0.025 | -0.142 | -0.796 | 1 |
| tumor side at left | 0.024 | -0.187 | -0.103 | 0.306 |
| without antiHER2 therapy | 0.021 | 0.141 | 0 | 1 |
| with family history | 0.021 | 0.016 | 0.047 | 1 |
| modified stage III | 0.021 | 0.131 | 0.019 | 1 |
| modified stage I | 0.021 | -0.094 | 0 | 1 |
| without endocrine therapy | 0.019 | -0.082 | -0.288 | 1 |
| without PR | 0.018 | 0.052 | -0.195 | 1 |
| adjuvant chemotherapy | 0.016 | -0.116 | -0.105 | 1 |
| premenopausal | 0.015 | 0.109 | 0.187 | 1 |
| without ER | 0.015 | -0.016 | 0.097 | 1 |
| without smoking history | 0.014 | 0.068 | 0 | 1 |
| with antiHER2 therapy | 0.012 | -0.119 | 0 | 1 |
| unknown drinking history | 0.011 | 0.024 | 0 | 1 |
| SLNB | 0.011 | 0.001 | 0.150 | 1 |
| RT technology: 2D-fields | 0.010 | -0.068 | 0 | 1 |
| BCT | 0.010 | 0.009 | -0.300 | 1 |
| unknown smoking history | 0.009 | 0.048 | 0 | 1 |
| with PR | 0.008 | -0.078 | 0 | 1 |
| postmenopausal | 0.008 | -0.047 | -0.151 | 1 |
| ALND | 0.008 | 0.034 | 0 | 1 |
| with endocrine therapy | 0.007 | 0.032 | 0 | 1 |
| none chemotherapy | 0.007 | -0.043 | -0.311 | 0.771 |
| electron: none | 0.006 | 0.000 | 0 | 1 |
| HR-/HER2+ | 0.005 | -0.046 | -0.244 | 1 |
| with ER | 0.005 | -0.040 | 0 | 1 |
| without family history | 0.004 | -0.025 | 0 | 1 |
| HR-/HER2- | 0.004 | 0.026 | 0 | 1 |
| chemotherapy regimens: others | 0.003 | 0.001 | 0 | 1 |
| tumor side at right | 0.003 | 0.027 | 0 | 1 |
| MRM | 0.002 | -0.018 | 0 | 1 |
| modified N stage 0 | 0.001 | 0.000 | 0 | 1 |
| electron: 16Gy/8fx | 0.001 | -0.004 | -0.273 | <0.001 |
| RT fields: Breast/chest wall with regional lymphatics | 0.001 | 0.017 | 0 | 1 |
| neoadjuvant+adjuvant chemotherapy | 0 | 0 | -0.225 | 1 |
| with drinking history | 0 | 0 | 0 | 1 |
| clear margin | 0 | 0 | 0.391 | <0.001 |
| close or positive margin | 0 | 0 | 0 | 1 |
| perimenopausal | 0 | 0 | -0.281 | 0.76 |
| modified N stage more than 0 | 0 | 0 | 0 | 1 |
| RT Dose: 40.5Gy/15fx | 0 | 0 | -0.456 | 1 |
| RT Dose: more than 50Gy/25fx | 0 | 0 | 0 | 1 |
| RT fields: Tangential breast only | 0 | 0 | 0 | 1 |
| with smoking history | 0 | 0 | -0.600 | 0.017 |
SHAP value is more than zero, the higher SHAP value the more contribution of feature to lymphopenia; direction of SHAP is range from -1 to 1, more promotive to lymphopenia when close to 1 while more protective when closet to -1. RT, radiation treatment; ER, estrogen receptors; PR, progesterone receptors; IHC, immunohistochemistry; HR, hormone receptor; HER2, human epidermal growth factor receptor 2; BCT, breast-conserving therapy; MRM, modified radical mastectomy; SLNB, Sentinel lymph node biopsy; ALND, axillary lymph node dissection.