Table 1. The proportion of missing data .

Variable Name	Number	Percent
Primary site of tumor	30	5.3
Histology of tumor	28	4.9
Tumor Size	31	5.4
Metastases of tumor	27	4.7
Stage of tumor	26	4.6
Behavior of tumor	22	3.9
Grade of tumor	35	6.2
Positive regional nodes	29	5.1
Removed regional nodes	37	6.5
Surgery of tumor	4	0.7
Human epidermal growth factor receptor 2(Her2)	131	23.0
Estrogen receptor	65	11.4
Progesterone receptor	65	11.4
Survival	5	0.9