Impact of Primary Site Surgery on Survival of Patients with de novo Stage IV Breast Cancer

Figures & data

Table 1 Characteristics of the Study Population

Variable	No. Patients (N = 243)	Percentage (%)
Age at diagnosis (years)
<50	122	50.2
≥50	121	49.8
Mean	50.04	–
Range	20–83	–
Histology
IDC	218	89.7
LC	8	3.3
Other	17	7.0
T stage
T1	5	2.1
T2	71	29.2
T3	31	12.7
T4	136	56.0
N stage
N0	14	5.8
N1	70	28.8
N2	77	31.7
N3	82	33.7
Metastatic site
Bone	134	55.1
Lung	99	40.7
Liver	72	29.6
Brain	15	6.2
Soft tissue	83	34.2
Visceral organ	147	60.5
Number of metastatic sites
<3	130	53.5
≥3	113	46.5
ER status
Positive	162	66.7
Negative	81	33.3
PR status
Positive	141	58.0
Negative	102	42.0
HER2 status
Positive	118	48.6
Negative	113	46.5
Unknown	12	4.9
Surgery
Yes	125	51.4
No	118	48.6
Chemotherapy
Yes	213	87.7
No	30	12.3
Hormone therapy
Yes	87	35.8
No	156	64.2
Anti-HER2 therapy
Yes	47	19.3
No	196	80.7
Radiotherapy
Yes	48	19.8
No	195	80.2

Abbreviations: IDC, infiltrative ductal carcinoma; LC, lobular-carcinoma; ER, estrogen receptor; HER2, human epidermal-growth factor 2; PR, progesterone receptor.

Table 2 Comparison of Clinical and Tumor Characteristic Between Surgery Group and No Surgery Group

Variable	Patients with Surgery (N = 125)	Patients without Surgery (N = 118)	P
Age at diagnosis (years)			0.854
<50	64(51.2%)	58(49.2%)
≥50	61(48.8%)	60(50.8%)
T stage			0.009
T1	4(3.2%)	1(0.8%)
T2	46(36.8%)	24(20.3%)
T3	17(13.6%)	14(11.9%)
T4	58(46.4%)	79(67.0%)
N stage			0.027
N0	12(9.6%)	2(1.7%)
N1	35(28.0%)	35(28.0%)
N2	41(32.8%)	36(30.5%)
N3	37(29.6%)	45(38.1%)
Metastatic site
Bone	69(55.2%)	66(55.9%)	0.909
Lung	39(31.2%)	60(50.8%)	0.002
Liver	34(27.2%)	38(32.2%)	0.395
Brain	5(4.0%)	10(8.5%)	0.158
Soft tissue	31(24.8%)	52(44.1%)	0.001
Visceral organ	64(51.2%)	84(71.2%)	0.001
Number of metastatic sites			0.327
<3	116(92.8%)	93(78.8%)
≥3	9(7.2%)	25(21.2%)
ER status			0.320
Positive	87(69.6%)	75(63.6%)
Negative	38(30.4%)	43(36.4%)
PR status			0.704
Positive	74(59.2%)	67(56.8%)
Negative	51(40.8%)	51(43.2%)
HER2 status			0.081
Positive	64(51.2%)	53(44.9%)
Negative	58(46.4%)	55(46.6%)
Unknown	3(2.4%)	10(8.5%)
Chemotherapy			0.136
Yes	119(95.2%)	94(79.7%)
No	6(4.8%)	24(20.3%)
Endocrine therapy			0.000
Yes	58(46.4%)	29(24.6%)
No	67(53.6%)	89(75.4%)
Anti-HER2 therapy			0.062
Yes	25(20.0%)	21(17.8%)
No	100(80.0%)	97(82.2%)
Radiotherapy
Yes	34(27.2%)	14(11.9%)	0.052
No	91(72.8%)	104(88.1%)

Abbreviations: IDC, infiltrative ductal carcinoma; LC, lobular carcinoma; ER, estrogen receptor; HER2, human epidermal growth factor 2; PR, progesterone receptor.

Table 3 Univariable Analysis Predicting OS in Stage IV Breast Cancer Patients

Variable	N	HR (95% CI)	P value
Surgery (yes vs no)	243	0.53 (0.36–0.86)	0.002
Age (<50 vs ≥50 yr)	243	1.12(0.75–1.27)	0.709
Bone metastasis	243	0.84 (0.63–1.63)	0.746
Visceral organ metastasis	243	2.15 (1.22–3.86)	0.000
Number of metastases(continuous)	243	1.24(0.69–1.54)	0.054
ER(+ vs.-)	243	0.66 (0.59–0.94)	0.001
PR(+ vs.-)	243	0.73 (0.58–0.82)	0.029
HER2(+ vs.-)	243	1.46 (0.62–1.83)	0.065

Abbreviations: HR, hazard ratio; ER, estrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor 2.

Table 4 Multivariable Analysis Predicting OS in Stage IV Breast Cancer Patients

Variable	N	HR (95% CI)	P value
Surgery (yes vs no)	243	0.56 (0.32–0.78)	0.000
Age (<50 vs ≥50 yr)	243	1.01(0.73–1.33)	0.812
Bone metastasis	243	0.79 (0.54–1.26)	0.062
Visceral organ metastasis	243	2.38 (1.37–3.35)	0.000
Number of metastases(continuous)	243	1.05 (0.72–1.48)	0.069
ER(+ vs.-)	243	0.54 (0.41–0.85)	0.000
PR(+ vs.-)	243	0.68 (0.55–0.82)	0.002
HER2(+ vs.-)	243	1.52 (0.81–1.66)	0.553

Abbreviations: HR, hazard ratio; ER, estrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor 2.

Figure 1 Kaplan–Meier curves estimate overall survival in de novo stage IV breast cancer (Median survival was 35 months in the surgery group vs 22 months in the no surgery group; Log rank test: P = 0.006).

Figure 2 Kaplan–Meier curves estimate overall survival in de novo stage IV breast cancer with bone metastasis only (Median survival was 40 months in the surgery group vs 23 months in the no surgery group; Log rank test: P = 0.017).

Figure 3 Kaplan–Meier curves estimate overall survival in de novo stage IV breast cancer with metastases sites ≤3 (Median survival was 35 months in the surgery group vs 22 months in the no surgery group; Log rank test: P = 0.014).

Figure 4 Kaplan–Meier curves estimate overall survival in de novo stage IV breast cancer with visceral metastases (Median survival was 26 months in the surgery group vs 23 months in the no surgery group; Log rank test: P = 0.685).