Interpectoral Lymph Node Dissection Can Be Spared in pN0/N1 Invasive Breast Cancer Undergoing Modified Radical Mastectomy: Single-Institution Experience from Mainland China

Figures & data

Table 1 Clinicopathologic Features of Patients Undergoing Modified Radical Mastectomy (N=214)

Variables	Number	%
Age (years)
≤ 50	103	48.1
> 50	111	51.7
Tumor side
Left	126	58.9
Right	88	41.1
Tumor location
Upper Outer Quadrant	98	45.8
Lower Outer Quadrant	37	17.3
Upper Inner Quadrant	41	19.2
Lower Inner Quadrant	38	17.7
Histologic grade (MRB)
G1	6	2.8
G2	107	50.0
G3	101	47.2
Tumor stage
T1	81	37.9
T2	115	53.7
T3	18	8.4
Lymph node involvement
N0	59	27.6
N1	66	30.8
N2	53	24.8
N3	36	16.8
AJCC stage
I	42	19.6
II	72	33.7
III	100	46.7
ER status
Positive	114	53.3
Negative	100	46.7
PR status
Positive	97	45.3
Negative	117	54.7
HER2 status
Positive	57	26.6
Negative	157	73.4
Ki67
Low (≤30%)	99	46.3
High (>30%)	115	53.7
Radiotherapy
Yes	165	77.1
No	49	22.9
Endocrine therapy
Yes	121	56.5
No	93	43.5
Trastuzumab use
Yes	50	23.4
No	164	76.6

Abbreviations: T, tumor; N, lymph-node; AJCC, American Joint Committee on Cancer; ER, estrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor receptor 2.

Table 2 Clinicopathologic Features of Patients with Interpectoral Lymph Node Occurrence (N=161)

Variables	Number	%
Age (years)
≤ 50	78	48.4
> 50	83	51.6
Tumor side
Left	99	61.5
Right	62	38.5
Tumor location
Upper Outer Quadrant	75	46.6
Lower Outer Quadrant	32	19.9
Upper Inner Quadrant	25	15.5
Lower Inner Quadrant	29	18.0
Histologic grade (MRB)
G1	5	3.1
G2	88	54.7
G3	68	42.2
Tumor stage
T1	61 (37.9)	37.9
T2	82 (50.9)	50.9
T3	18 (11.2)	11.2
Lymph node involvement
N0	37	23.0
N1	40	24.8
N2	46	28.6
N3	38	23.6
AJCC stage
I	32	19.9
II	41	25.4
III	88	54.7
ER status
Positive	88	54.7
Negative	73	45.3
PR status
Positive	72	44.7
Negative	89	55.3
HER2 status
Positive	44	27.3
Negative	117	72.7
Ki67
Low (≤30%)	85	52.8
High (>30%)	76	47.2
Radiotherapy
Yes	130	80.7
No	31	19.3
Endocrine therapy
Yes	92	57.1
No	69	42.9
Trastuzumab use
Yes	43	26.7
No	118	73.3

Abbreviations: T, tumor; N, lymph-node; AJCC, American Joint Committee on Cancer; ER, estrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor receptor 2.

Figure 1 Flow chart of the study.

Table 3 Univariate and Multivariate Analysis of Clinicopathological Factors Predicting IPN Occurrence (N=161)

Variables	Univariate (Chi Square/Fisher’s Exact)			Logistic Regression, Multivariate
	IPN Occurrence (Yes/No)		P	OR	95% CI	P
Age (years)
≤ 50	78	25
> 50	83	28	0.872	–	–	–
Tumor side
Left	97	29
Right	64	24	0.478	–	–	–
Tumor location
Upper Outer Quadrant	70	28
Others	91	25	0.236	–	–	–
Histologic grade (HMB)
G1–G2	93	20
G3	68	33	0.011	0.480	0.211–1.089	0.079
Tumor stage
T1	61	20
T2	82	33
T3	18	0	0.032	0.957	0.452–2.026	0.908
Number of ALND
≤ 20	108	41
> 20	53	12	0.158	–	–	–
ALN involvement
N0	37	22
N1	40	26
N2	48	5
N3	36	0	<0.001	8.292	3.240−21.221	<0.001
ER status
Positive	88	26
Negative	73	27	0.478	–	–	–
PR status
Positive	72	25
Negative	89	28	0.756	–	–	–
HER2 status
Positive	44	13
Negative	117	40	0.689	–	–	–
Ki67 label index
Low (≤30%)	85	14
High (>30%)	76	39	0.001	0.482	0.220–1.056	0.076
Molecular typing
Luminal A/B	90	27
HER2 over-expression	33	5
Triple negative	38	21	0.036	1.212	0.765–1.920	0.413

Abbreviations: T, tumor; N, lymph-node; ALN, axillary lymph node; ALND, axillary lymph node dissection; ER, estrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor receptor 2.

Table 4 Univariate and Multivariate Analysis of Clinicopathological Factors Predicting IPN Metastasis (N=161)

Variables	Univariate (Chi Square/Fisher’s Exact)			Logistic Regression, Multivariate
	IPN Occurrence (Yes/No)		P	OR	95% CI	P
Age (years)
≤ 50	20	58
> 50	26	57	0.425	–	–	–
Tumor side
Left	24	75
Right	22	40	0.124	–	–	–
Tumor location
Upper Outer Quadrant	24	51
Others	22	64	0.368	–	–	–
Histologic grade (HMB)
G1–G2	24	69
G3	22	46	0.364	–	–	–
Tumor stage
T1	10	51
T2	30	52
T3	6	12	0.027	1.271	0.758−2.131	0.364
Number of ALND
≤ 20	27	77
> 20	19	38	0.322	–	–	–
ALN involvement
N0	0	37
N1	2	38
N2	12	34
N3	32	6	<0.001	13.423	7.529−23.931	<0.001
ER status
Positive	18	70
Negative	28	45	0.012	2.608	0.520–13.709	0.244
PR status
Positive	16	56
Negative	30	59	0.109	–	–	–
HER2 status
Positive	16	28
Negative	30	87	0.180	–	–	–
Ki67 label index
Low (≤30%)	24	61
High (>30%)	22	54	0.920	–	–	–
Molecular typing
Luminal A/B	18	72
HER2 over-expression	14	19
Triple negative	38	21	0.022	1.035	0.399–2.685	0.943

Abbreviations: T, tumor; N, lymph-node; ALN, axillary lymph node; ALND, axillary lymph node dissection; ER, estrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor receptor 2.