Introduction: Neoadjuvant chemotherapy (NAC) is extensively employed in breast cancer (BC), primarily for aggressive subtypes like triple-negative and human epidermal growth factor receptor 2 (HER2)-positive BC and in estrogen receptor-positive (ER+)/HER2− BC with high-risk features. In ER+/HER2− BC, pathological complete rates are much lower (<10%), while axillary dissection rates are higher. This study focuses on hormone receptor-positive (HR+)/HER2− BC patients undergoing NAC, examining its impact on pathological complete response (pCR) rates, with specific attention to tumor Ki67 and ER status. Methods: Retrospective data analysis from Kartal Dr. Lütfi Kırdar City Hospital included HR+/HER2− BC patients who received NAC. Clinicopathological factors, NAC response, and surgical outcomes were assessed. Statistical analyses evaluated the association between Ki67, ER status, and pCR. Results: Of 203 patients, 11.8% achieved pCR. Ki67 (p < 0.001) and ER percentage (p < 0.001) significantly correlated with pCR. Higher Ki67 was associated with increased pCR likelihood (HR: 1.03, 95% CI: 1.01–1.05). A Ki67-pCR probability curve revealed a cutoff of 23.5%. ER%-pCR analysis showed decreasing pCR rates with higher ER percentages. Multivariate analysis confirmed Ki67 (p = 0.003, HR: 1.02) and ER percentage (p = 0.019, HR: 0.97) as independent predictors of pCR probability. Conclusion: Consideration of Ki67 and ER percentage aids in NAC decisions for HR+/HER2− BC, identifying patients with high NAC response rates, facilitating axillary preservation, and potentially avoiding axillary dissection. The pCR rates in patients with Ki67 ≤24 are particularly low, especially in patients with a high ER percentage. In these cases, upfront surgery and adjuvant treatment should be considered instead of NAC.

1.
Murphy
BL
,
Day
CN
,
Hoskin
TL
,
Habermann
EB
,
Boughey
JC
.
Neoadjuvant chemotherapy use in breast cancer is greatest in excellent responders: triple-negative and HER2+ subtypes
.
Ann Surg Oncol
.
2018
;
25
(
8
):
2241
8
. .
2.
Kim
HS
,
Yoo
TK
,
Park
WC
,
Chae
BJ
.
Potential benefits of neoadjuvant chemotherapy in clinically node-positive luminal subtype(-) breast cancer
.
J Breast Cancer
.
2019
;
22
(
3
):
412
24
. .
3.
Barbieri
E
,
Gentile
D
,
Bottini
A
,
Sagona
A
,
Gatzemeier
W
,
Losurdo
A
, et al
.
Neo-adjuvant chemotherapy in luminal, node positive breast cancer: characteristics, treatment and oncological outcomes: a single center’s experience
.
Eur J Breast Health
.
2021
;
17
(
4
):
356
62
. .
4.
Yau
C
,
Osdoit
M
,
van der Noordaa
M
,
Shad
S
,
Wei
J
,
de Croze
D
, et al
.
Residual cancer burden after neoadjuvant chemotherapy and long-term survival outcomes in breast cancer: a multicentre pooled analysis of 5161 patients
.
Lancet Oncol
.
2022
;
23
(
1
):
149
60
. .
5.
Boughey
JC
,
Ballman
KV
,
McCall
LM
,
Mittendorf
EA
,
Symmans
WF
,
Julian
TB
, et al
.
Tumor biology and response to chemotherapy impact breast cancer-specific survival in node-positive breast cancer patients treated with neoadjuvant chemotherapy: long-term follow-up from ACOSOG Z1071 (alliance)
.
Ann Surg
.
2017
;
266
(
4
):
667
76
. .
6.
Horimoto
Y
,
Arakawa
A
,
Tanabe
M
,
Sonoue
H
,
Igari
F
,
Senuma
K
, et al
.
Ki67 expression and the effect of neo-adjuvant chemotherapy on luminal HER2-negative breast cancer
.
BMC Cancer
.
2014
;
14
:
550
. .
7.
Bustreo
S
,
Osella-Abate
S
,
Cassoni
P
,
Donadio
M
,
Airoldi
M
,
Pedani
F
, et al
.
Optimal Ki67 cut-off for luminal breast cancer prognostic evaluation: a large case series study with a long-term follow-up
.
Breast Cancer Res Treat
.
2016
;
157
(
2
):
363
71
. .
8.
Ogston
KN
,
Miller
ID
,
Payne
S
,
Hutcheon
AW
,
Sarkar
TK
,
Smith
I
, et al
.
A new histological grading system to assess response of breast cancers to primary chemotherapy: prognostic significance and survival
.
Breast
.
2003
;
12
(
5
):
320
7
. .
9.
Teshome
M
,
Kuerer
HM
.
Breast conserving surgery and locoregional control after neoadjuvant chemotherapy
.
Eur J Surg Oncol
.
2017
;
43
(
5
):
865
74
. .
10.
Torrisi
R
,
Marrazzo
E
,
Agostinetto
E
,
De Sanctis
R
,
Losurdo
A
,
Masci
G
, et al
.
Neoadjuvant chemotherapy in hormone receptor-positive/HER2-negative early breast cancer: when, why and what
.
Crit Rev Oncol Hematol
.
2021
;
160
:
103280
. .
11.
Mamtani
A
,
Barrio
AV
,
King
TA
,
Van Zee
KJ
,
Plitas
G
,
Pilewskie
M
, et al
.
How often does neoadjuvant chemotherapy avoid axillary dissection in patients with histologically confirmed nodal metastases? Results of a prospective study
.
Ann Surg Oncol
.
2016
;
23
(
11
):
3467
74
. .
12.
Harbeck
N
,
Gluz
O
.
Neoadjuvant therapy for triple negative and HER2-positive early breast cancer
.
Breast
.
2017
;
34
(
Suppl 1
):
S99
03
. .
13.
Houssami
N
,
Macaskill
P
,
von Minckwitz
G
,
Marinovich
ML
,
Mamounas
E
.
Meta-analysis of the association of breast cancer subtype and pathologic complete response to neoadjuvant chemotherapy
.
Eur J Cancer
.
2012
;
48
(
18
):
3342
54
. .
14.
von Minckwitz
G
,
Untch
M
,
Blohmer
JU
,
Costa
SD
,
Eidtmann
H
,
Fasching
PA
, et al
.
Definition and impact of pathologic complete response on prognosis after neoadjuvant chemotherapy in various intrinsic breast cancer subtypes
.
J Clin Oncol
.
2012
;
30
(
15
):
1796
804
. .
15.
Boughey
JC
,
McCall
LM
,
Ballman
KV
,
Mittendorf
EA
,
Ahrendt
GM
,
Wilke
LG
, et al
.
Tumor biology correlates with rates of breast-conserving surgery and pathologic complete response after neoadjuvant chemotherapy for breast cancer: findings from the ACOSOG Z1071 (Alliance) Prospective Multicenter Clinical Trial
.
Ann Surg
.
2014
;
260
(
4
):
608
16
; discussion 14-6. .
16.
Pilewskie
M
,
Zabor
EC
,
Mamtani
A
,
Barrio
AV
,
Stempel
M
,
Morrow
M
.
The optimal treatment plan to avoid axillary lymph node dissection in early-stage breast cancer patients differs by surgical strategy and tumor subtype
.
Ann Surg Oncol
.
2017
;
24
(
12
):
3527
33
. .
17.
Kim
KI
,
Lee
KH
,
Kim
TR
,
Chun
YS
,
Lee
TH
,
Park
HK
.
Ki-67 as a predictor of response to neoadjuvant chemotherapy in breast cancer patients
.
J Breast Cancer
.
2014
;
17
(
1
):
40
6
. .
18.
Jain
P
,
Doval
DC
,
Batra
U
,
Goyal
P
,
Bothra
SJ
,
Agarwal
C
, et al
.
Ki-67 labeling index as a predictor of response to neoadjuvant chemotherapy in breast cancer
.
Jpn J Clin Oncol
.
2019
;
49
(
4
):
329
38
. .
19.
Denkert
C
,
Loibl
S
,
Müller
BM
,
Eidtmann
H
,
Schmitt
WD
,
Eiermann
W
, et al
.
Ki67 levels as predictive and prognostic parameters in pretherapeutic breast cancer core biopsies: a translational investigation in the neoadjuvant GeparTrio trial
.
Ann Oncol
.
2013
;
24
(
11
):
2786
93
. .
20.
Ding
W
,
Ye
D
,
Zhu
H
,
Lin
Y
,
Li
Z
,
Ruan
G
.
Survival benefit of adjuvant chemotherapy in node-positive breast cancer with a 21-gene recurrence score of 14 to 25: a real-world study based on the inverse probability of treatment weighting method
.
Clin Breast Cancer
.
2023
;
23
(
7
):
e441
50
. .
You do not currently have access to this content.