Table 3. Univariate analysis of factors impacting the incidence of IDC.

Variables	Assignment	N	Lymphedema case (%)	χ2	P
Lymph node metastasis
	No	1150	102 (8.9)	14.158	0.000
	Yes	999	140 (14.0)
The number of metastatic lymph nodes
	≤3 (N1 Group)	1746	185 (10.6)	5.583	0.054
	4–9 (N2 Group)	241	30 (12.4)
	≥10 (N3 Group)	162	27 (16.7)
Tumor size
	≤2cm	925	100 (10.8)	0.728	0.867
	2–5cm	1083	126 (11.6)
	>5cm	136	15 (11.0)
Neoadjuvant chemotherapy
	No	1755	197 (11.2)	0.143	0.931
	Yes	393	45 (11.5)