Table 1 Characteristics of baseline of patients in the NSM/SSM and TM groups before and after propensity score matching

Operation on axillary lymph nodes, n (%)

0.093

0.090

0.150

0.105

 ALND

713 (72.312)

369 (68.207)

400 (68.493)

216 (73.220)

 SLNB

271 (27.485)

171 (31.608)

182 (31.164)

78 (26.441)

 No operation

2 (0.203)

1 (0.185)

2 (0.342)

1 (0.339)

Age, n (%)

< 0.001

0.307

0.685

0.056

 <35

189 (19.325)

169 (31.355)

140 (23.972)

67 (22.712)

 ≥35, <55

762 (77.914)

365 (67.718)

434 (74.315)

224 (75.932)

 ≥55

27 (2.761)

5 (0.928)

10 (1.712)

4 (1.356)

Size, n (%)

< 0.001

0.580

0.824

0.047

 0

5 (0.517)

1 (0.186)

3 (0.514)

1 (0.339)

 <2 cm

254 (26.267)

210 (39.033)

211 (36.130)

105 (35.593)

 2–5

290 (29.990)

224 (41.636)

205 (35.103)

105 (35.593)

 ≥5

23 (2.378)

17 (3.160)

17 (2.911)

7 (2.373)

 NA

395 (40.848)

86 (15.985)

148 (25.342)

77 (26.102)

Quadrant, n (%)

< 0.001

0.630

0.975

0.065

 Upper outer

270 (27.467)

235 (43.519)

213 (36.473)

103 (34.915)

 Lower inner

56 (5.697)

28 (5.185)

35 (5.993)

15 (5.085)

 Lower outer

84 (8.545)

78 (14.444)

69 (11.815)

35 (11.864)

 Upper inner

122 (12.411)

95 (17.593)

99 (16.952)

55 (18.644)

 Central

32 (3.255)

17 (3.148)

19 (3.253)

9 (3.051)

 NA

419 (42.625)

87 (16.111)

149 (25.514)

78 (26.441)

Distance of the tumor from the nipple, n (%)

< 0.001

0.569

0.536

0.118

 0–1

164 (16.633)

99 (18.299)

117 (20.034)

61 (20.678)

 >1, ≤2

93 (9.432)

99 (18.299)

67 (11.473)

43 (14.576)

 >2, ≤5

243 (24.645)

191 (35.305)

193 (33.048)

91 (30.847)

 >5, ≤8

40 (4.057)

39 (7.209)

35 (5.993)

13 (4.407)

 NA

446 (45.233)

113 (20.887)

172 (29.452)

87 (29.492)

Histological type, n (%)

0.373

0.092

0.480

0.059

 DCIS

134 (13.590)

88 (16.266)

85 (14.555)

40 (13.559)

 IDC

803 (81.440)

422 (78.004)

465 (79.623)

234 (79.322)

 ILC

13 (1.318)

10 (1.848)

12 (2.055)

7 (2.373)

 Mixed

14 (1.420)

9 (1.664)

9 (1.541)

6 (2.034)

 Others

22 (2.231)

12 (2.218)

13 (2.226)

8 (2.712)

pT, n (%)

0.697

0.035

0.448

0.138

 0

34 (3.448)

20 (3.697)

22 (3.767)

17 (5.763)

 1

408 (41.379)

229 (42.329)

252 (43.151)

126 (42.712)

 2

482 (48.884)

257 (47.505)

267 (45.719)

133 (45.085)

 3

58 (5.882)

32 (5.915)

40 (6.849)

19 (6.441)

 4

4 (0.406)

3 (0.555)

3 (0.514)

0 (0.000)

pN, n (%)

< 0.001

0.417

0.773

0.041

 0

619 (62.779)

379 (70.055)

402 (68.836)

206 (69.831)

 1

161 (16.329)

101 (18.669)

110 (18.836)

54 (18.305)

 2

54 (5.477)

36 (6.654)

36 (6.164)

16 (5.424)

 3

20 (2.028)

12 (2.218)

12 (2.055)

7 (2.373)

 NA

132 (13.387)

13 (2.403)

24 (4.110)

12 (4.068)

Stage, n (%)

0.573

0.032

0.481

0.089

 0

20 (2.028)

12 (2.218)

14 (2.397)

11 (3.729)

 I

273 (27.688)

154 (28.466)

169 (28.938)

85 (28.814)

 II

511 (51.826)

281 (51.941)

295 (50.514)

151 (51.186)

 III

182 (18.458)

94 (17.375)

106 (18.151)

48 (16.271)

Neoadjuvant chemotherapy, n (%)

0.682

0.022

0.842

0.014

 No

866 (87.830)

479 (88.540)

514 (88.014)

261 (88.475)

 Yes

120 (12.170)

62 (11.460)

70 (11.986)

34 (11.525)

Post mastectomy irradiation, n (%)

0.414

0.044

1.000

0.000

 No

643 (65.213)

364 (67.283)

390 (66.781)

197 (66.780)

 Yes

343 (34.787)

177 (32.717)

194 (33.219)

98 (33.220)

Post mastectomy chemotherapy, n (%)

0.776

0.015

0.861

0.013

 No

18 (1.826)

11 (2.033)

15 (2.568)

7 (2.373)

 Yes

968 (98.174)

530 (97.967)

569 (97.432)

288 (97.627)

Endocrine therapy, n (%)

0.458

0.040

0.638

0.034

 No

239 (24.239)

122 (22.551)

143 (24.486)

68 (23.051)

 Yes

747 (75.761)

419 (77.449)

441 (75.514)

227 (76.949)

Targeted therapy, n (%)

< 0.001

0.295

0.294

0.076

 No

846 (85.801)

401 (74.122)

470 (80.479)

246 (83.390)

 Yes

140 (14.199)

140 (25.878)

114 (19.521)

49 (16.610)

ER, n (%)

0.286

0.057

0.524

0.046

 Negative

254 (25.761)

126 (23.290)

144 (24.658)

67 (22.712)

 Positive

732 (74.239)

415 (76.710)

440 (75.342)

228 (77.288)

PR, n (%)

0.219

0.066

0.646

0.033

 Negative

303 (30.730)

150 (27.726)

171 (29.281)

82 (27.797)

 Positive

683 (69.270)

391 (72.274)

413 (70.719)

213 (72.203)

Ki67, n (%)

0.145

0.084

0.553

0.049

 Negative

448 (45.436)

224 (41.405)

264 (45.205)

140 (47.458)

 Positive

524 (53.144)

310 (57.301)

311 (53.253)

150 (50.847)

 NA

14 (1.420)

7 (1.294)

9 (1.541)

5 (1.695)

HER2, n (%)

0.305

0.055

0.426

0.057

 Negative

550 (55.781)

287 (53.050)

334 (57.192)

177 (60.000)

 Positive

436 (44.219)

254 (46.950)

250 (42.808)

118 (40.000)

Grade, n (%)

0.078

0.142

0.905

0.068

 0

266 (26.978)

114 (21.072)

141 (24.144)

68 (23.051)

 1

17 (1.724)

12 (2.218)

14 (2.397)

10 (3.390)

 2

322 (32.657)

194 (35.860)

199 (34.075)

104 (35.254)

 3

381 (38.641)

221 (40.850)

230 (39.384)

113 (38.305)

Number of nodules shown by ultrasound, n (%)

< 0.001

0.606

0.413

0.096

 1

841 (85.294)

329 (60.813)

455 (77.911)

223 (75.593)

 2

45 (4.564)

60 (11.091)

41 (7.021)

22 (7.458)

 3

5 (0.507)

18 (3.327)

5 (0.856)

1 (0.339)

 4

0 (0.000)

3 (0.555)

0 (0.000)

0 (0.000)

 5

0 (0.000)

1 (0.185)

0 (0.000)

0 (0.000)

 Several

90 (9.128)

130 (24.030)

83 (14.212)

49 (16.610)

 NA

5 (0.507)

0 (0.000)

0 (0.000)

0 (0.000)

Multifocal cancer, n (%)

0.001

0.160

0.910

0.029

 No

975 (98.884)

522 (96.488)

574 (98.288)

291 (98.644)

 Yes

11 (1.116)

19 (3.512)

10 (1.712)

4 (1.356)

The presence of calcifications, n (%)

< 0.001

0.338

0.560

0.042

 No

802 (81.339)

361 (66.728)

441 (75.514)

228 (77.288)

 Yes

184 (18.661)

180 (33.272)

143 (24.486)

67 (22.712)