Table 1 Study and patient characteristics

You et al. 2017 [14]

Retrospective study; Single center

90 patients with unilateral breast cancer

49.84 ± 10.04 years, 28 – 69 years

50/90; pCR group: 13/25; non-pCR group: 37/65

72 IDC, 5 DCIS, 2 ILC and 11 tumor classification unclear

CEF (n = 5), PC (n = 20), PE (n = 2), (n = 29) and PCH (n = 39); 6 or 8 cycles

27.78%

pCR or non-pCR; The absence of invasive carcinoma (residual DCIS allowed) by pathologic examination

Rella et al. 2020 [15]

Retrospective study; Single center

228 patients with unilateral breast cancer

47.6 ± 10 years, 24 – 74 years

pCR group: 18/30; non-pCR group: 121/198

162 IDC, 29 ILC and 37 other invasive carcinomas

A combination of doxorubicin and cyclophosphamide (2—4 cycles) and taxanes (+ trastuzumab if HER2-positive)

13.2%

pCR or non-pCR; The absence of residual invasive cancer cells in the breast and ipsilateral lymph nodes (DCIS may have been present) (ypT0/is, ypN0)

Preibsch et al. 2016 [16]

Retrospective study; Single center

73 patients with 80 biopsy-proven breast cancers

48.5 ± 9.9 years; 26.8 – 71.2 years

NR

71 IDC, 8 ILC and 1 invasive apocrine carcinoma

EC + docetaxel (n = 75), trastuzumab and zoledronic acid (n = 1), paclitaxel and avastin (n = 1), taxol and herceptin (n = 2) and vinorelbine and trastuzumab (n = 1)

CR (19%); PR (57%)

According to RECIST 1.1 criteria; CR (the disappearance of all target lesions was reached); PR (at least 30% decrease in the sum of the diameters of target lesions in comparison with the baseline sum diameters); SD and PD

Onishi et al. 2021 [19]

Retrospective study; Multiple center

882 patients with unilateral breast cancer (with breast cancer at high risk for early recurrence)

48 ± 10 years; NR

457/882

NR

Paclitaxel and/or a combination of 9 experimental agents (12 cycles), followed by anthracycline-cyclophosphamide (4 cycles; + trastuzumab if HER2-positive)

33%

pCR or non-pCR; The absence of residual invasive carcinoma in the breast and axillary lymph nodes after NAC

Chen et al. 2015 [17]

Retrospective study; Single center

46 patients with unilateral breast cancer

50 ± 11 years; NR

NR

40 IDC, 5 ILC and 1 mixed IDC and ILC

Dose-dense AC (2—4 cycles) followed by taxane regimen (After the patient received 2 cycles of AC, the oncologist determined the response and decided the next regimen)

52%

pCR or non-pCR; The absence of malignant cancer cells

Dong et al. 2018 [20]

Retrospective study; Single center

51 patients with HER2-positive unilateral IDC

46.24 ± 8.79 years; 27 – 63 years

27/51; pCR group: 14/23; non-pCR group: 13/28

All were HER2-positive IDC

Docetaxel, carboplatin, and trastuzumab (n = 29); doxorubicin, cyclophosphamide, docetaxel, and trastuzumab (n = 22); at least 6 or 8 cycles

45.1%

pCR or non-pCR; No residual tumor or only DCIS

You et al. 2018 [21]

Retrospective study; Single center

71 patients with HER2-positive unilateral breast cancer

47.65 ± 10.10 years; 26 – 71 years

37/71

70 IDC, 1 ILC

4 cycles of paclitaxel, carboplatin in combination, and trastuzumab

47.89%

pCR or non-pCR; The absence of residual invasive cancer upon hematoxylin and eosin evaluation of a complete resected breast specimen and all sampled regional lymph nodes following completion of neoadjuvant systemic therapy

Choi et al. 2015 [22]

NR

98 patients with invasive breast carcinoma (1 patient with bilateral breast cancer)

50 years; 29 – 81 years

NR

76 IDC; 3 ILC; 1 invasive carcinoma with signet ring cell, 1 IMPC, 8 DCIS, 1 LCIS, and 1 sclerosing adenosis (no tumors remained in 7 cases)

AT (n = 47); AC (n = 13); C-LTZ (n = 1); C-EPRV (n = 1); C-CPV (n = 1); EP (n = 3); EC (n = 15); ET (n = 17); DP (n = 1); 4 or 6 cycles

17.3%

pCR or non-pCR; The absence of microscopic residual tumor or invasive foci but the presence of DCIS

Arasu et al. 2020 [23]

Prospective study; Multiple center

88 patients with HER2-negative stage II or III breast cancer

pCR: 46.9 years; non-pCR: 48.8 years

pCR group: 20/29; non-pCR group: 35/59

NR

Paclitaxel alone or in combination with experimental NAC agents for 12 cycles, followed by 4 cycles of AC

33.0%

pCR or non-pCR; The absence of residual invasive cancer in the breast or lymph nodes at the time of surgery

Oh et al. 2018 [24]

Retrospective study; Single center

186 patients with invasive breast cancer

45 years; 25 – 81 years

128/186

NR

Adriamycin with cyclophosphamide plus docetaxel (n = 126); HER2 targeted agent-based regimens (n = 22); adriamycin with cyclophosphamide (n = 20); and FEC (n = 18)

20.4%

pCR or non-pCR; The absence of residual invasive cancer cells in the breast and ipsilateral lymph nodes (DCIS may have been present) (ypT0/is, ypN0)

La Forgia et al. 2021 [25]

Retrospective study; Single center

80 patients with breast cancer from stage I to stage II

49 years; 31 – 80 years

32/80

NR

4 cycles of anthracycline combined with cyclophosphamide, and only taxanes (with and without anti-HER2-positive therapy) in the following 3 months

CR (15%); PR (55%)

According to RECIST 1.1 criteria; CR (Disappearance of all target lesions; Any pathological lymph nodes must have reduction in short axis to < 10 mm); PR (At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters); SD and PD

Teixeira et al. 2018 [18]

Retrospect cross-sectional observational study; Dual center

150 patients with unilateral invasive breast cancer

45.2 years; 20 – 74 years

NR

NR

NR

NR

pCR or non-pCR; NR

Moliere et al. 2019 [26]

Retrospective study; Single center

102 patients with breast cancer

49.8 years; NR

54/102

NR

FEC (n = 84), additional weekly taxanes (n = 51) and trastuzumab (n = 33)

26.5%

pCR or non-pCR; The absence of residual invasive tumor in both the breast and the axillary nodes