Factors predicting upstaging from clinical N0 to pN2a/N3a in breast cancer patients

Table 1 Background characteristics of all patients

Background characteristics (n = 135)
Age (yr)	56 (35-84)
SUVmax of primary tumor	3.05 (0.8-11.9)
pN1	113
pN2a or pN3a	22
The invasion diameter of the primary lesion
≤ 20 mm	67
< 50 mm	55
≥ 50 mm	11
NA	2
Maximal diameter of metastasis in the sentinel lymph nodes (mm)	3 (0.1-25)
The number of SLN metastasis
1	112
2	19
3	4
ER
Positive	118
Negative	14
Unknown	3
HER2
Positive	8
Negative	125
Unknown	2
Nuclear grade of biopsy specimen
1, 2	103
3	26
Unknown	6
FDG accumulation of axillary lymph nodes
Yes	19
No	116

SUV: Standardized uptake value; NA: Not applicable; SLN: Sentinel lymph node; ER: Estrogen receptor; HER2: Human epidermal growth factor receptor 2; FDG: Fluorodeoxyglucose.

Table 2 Comparison between pN1 and pN2a/pN3a

Total (n = 135)	pN1	pN2a/pN3a	P value
	n = 113	n = 22
Age	57.96 ± 12.14	59.64 ± 12.73	0.56
The invasion diameter of the primary lesion (mm)	22.77 ± 14.76	39.86 ± 21.73	< 0.001
Maximal diameter of metastasis in the SLNs	3.46 ± 2.80	9.19 ± 5.66	< 0.001
The number of SLN metastasis			0.014
1	98	14
2 and more	15	8
ER			0.47
Positive	100	18
Negative	11	3
Unknown	2	1
HER2			1
Positive	7	1
Negative	104	21
Unknown	2	0
Nuclear grade of biopsy specimen			0.77
1, 2	87	16
3	21	5
Unknown	4	1
SUVmax of the primary tumor	3.80 ± 2.50	4.13 ± 2.77	0.61
FDG accumulation of axillary lymph nodes			< 0.001
No	104	11
Yes	8	11
Unknown	1	0

ER: Estrogen receptor; HER2: Human epidermal growth factor receptor 2; SLN: Sentinel lymph node; SUV: Standardized uptake value; FDG: Fluorodeoxyglucose.

Table 3 Uni- and multivariate logistic regression analysis of risk factors associated with upstaging pN2a/pN3a

Factors	Univariate logistic regression analysis to predictive factors of pN2a/pN3a			Multivariate logistic regression analysis to predictive factors of pN2a/pN3a
	Odds ratio	95%CI	P value	Odds ratio	95%CI	P value
Age (yr) (< 50 vs ≥ 50)	0.863	0.333-2.24	0.76
ER (positive vs negative)	0.66	0.167-2.60	0.55
HER2 (positive vs negative)	0.833	0.954-7.28	0.87
Invasive diameter of the primary site (≤ 20 mm vs > 20 mm)	4.3	1.48-12.50	0.007	3.53	0.963-13.0	0.057
Nuclear grade (1, 2 vs 3)	1.29	0.426-3.393	0.65
Total positive SLNs (1 vs 2 and more)	3.73	1.34-10.40	0.012	3.92	1.01-15.3	0.048
Maximal diameter of metastasis in the SLNs (< 5 mm vs ≥ 5 mm)	21.2	4.68-96.3	< 0.001	15.6	3.08-79.2	< 0.001
SUVmax of primary tumor (< 3.1 vs ≥ 3.1)	0.96	0.351-2.62	0.94
FDG accumulation of axillary lymph nodes (yes vs no)	13	4.32-39.2	< 0.001	4.84	1.29-18.2	0.02

ER: Estrogen receptor; HER2: Human epidermal growth factor receptor 2; SLN: Sentinel lymph node; SUV: Standardized uptake value; FDG: Fluorodeoxyglucose.