†These authors contributed equally.
Academic Editor: Gianluca Franceschini
Objective: This study aimed to investigate the
clinical molecular characteristics in patients with human epidermal growth factor
receptor 2 (HER2)-negative breast cancer and axillary lymph node metastasis and
explored the related factors of the neoadjuvant chemotherapy (NAC) response.
Methods: The data of 185 patients with HER2-negative breast cancer and
axillary lymph node metastasis who were treated in the Department of Breast
Center of the Affiliated Hospital of Qingdao University from July 2017 to July
2021 were retrospectively analyzed. The clinical features and the related factors
for the responses of the primary tumor and axillary lymph node metastasis to NAC
were analyzed. Statistical analysis was conducted using the SPSS 26.0 statistical
software. Univariate analysis was conducted using the
Breast cancer is the most commonly occurring cancer among women worldwide. As the incidence continues to increase, this disease seriously endangers the physical and mental health of women [1].
Since the last century, neoadjuvant therapy has been clinically applied. Neoadjuvant therapy includes neoadjuvant chemotherapy (NAC), neoadjuvant targeted therapy, and neoadjuvant endocrine therapy. Guidelines at home and abroad reflect neoadjuvant therapy as a standard treatment for locally advanced breast cancer. The application of targeted therapy, especially a double target combination, shows a higher pathological complete remission (pCR) rate in neoadjuvant therapy for human epidermal growth factor receptor 2 (HER2)-positive breast cancer, and the long-term survival rate of patients with pCR rates is higher than that of those who did not receive the treatment [2]. The overall effective rate of NAC in patients with breast cancer is 60%–90%, but there are still 10%–35% of patients with poor efficacy and even poor progression during chemotherapy [3]. Patients with hormone receptor-positive breast cancer are not sensitive to NAC. These patients have a pCR rate of 6%–12%, while patients that are HER2-negative have a pCR rate of approximately 7% [4, 5]. The complete remission (CR) rate of NAC based on paclitaxel and anthracycline administration in triple negative breast cancer is 30%–40% [6].
The HER2 protein expression level is assessed by immunohistochemistry (IHC) and in situ hybridization (ISH) [7]. A HER2-negative result includes a low HER2 expression (IHC1+ or IHC2+ and fluorescence in situ hybridization-negative) and a zero HER2 expression (IHC0). Antibody-coupled drugs provide new therapeutic options for patients with breast cancer, including those with a low expression of HER2. The latest study published in The Lancet [8] revealed that the hormone receptor-positive rate, pCR rate, disease-free survival rate, and overall survival rate were different between low HER2 expression tumors and zero HER2 expression tumors. Low HER2 expression tumors have unique biological characteristics, different therapeutic effects, and survival results, especially for drug-resistant and hormone receptor-negative tumors.
In the present study, the investigators studied the factors related to NAC for HER2-negative breast cancer, primary breast cancer, and axillary lymph node double metastasis breast cancer. Furthermore, HER2-negative cancers were divided into three subgroups to study their clinical molecular characteristics; this is helpful for subtype refinement and precise treatment of HER2-negative breast cancer. For patients with poor efficacy of NAC, preliminary screening can be performed based on clinical molecular characteristics, and patients with low HER2 expressions can be treated with antibody–drug conjugate (ADC) drugs.
The data of patients with breast cancer who were treated in the Department of Breast Center of the Affiliated Hospital of Qingdao University from July 2017 to July 2021 were retrospectively analyzed. Neoadjuvant chemotherapy and surgery were performed in the Department of Breast Center.
The inclusion criteria were as follows: if the primary tumors and axillary lymph node tumors were diagnosed as invasive carcinoma by a core needle biopsy; patients who were female; if the immunohistochemical information included estrogen receptor (ER), progesterone receptor (PR), HER2, and Ki67; if there was no presence of distant metastasis; patients who had not received malignant tumor-related treatment before the treatment administered in this study; if the first-line regimen of NAC was anthracycline combined with paclitaxel or anthracycline sequential paclitaxel; patients who had undergone a modified radical mastectomy.
The exclusion criteria were as follows: if the primary tumor had been diagnosed as a carcinoma in situ or a specific type of cancer; women who were pregnant or lactating; if the immunohistochemical information was uncertain or insufficient; patients with distant metastasis; patients who had received malignant tumor-related treatment before the treatment administered in this study; if there had been a change of NAC regimen; if a mastectomy had not been performed or an axillary lymph node dissection had not been completed.
Patients who were HER2-negative were divided into three groups: an IHC0, IHC1+, and IHC2+/ISH– group. The NAC responses of the primary tumors were divided into the G1–G3 and G4–G5 groups according to the Miller–Payne grades. The treatment responses of the axillary lymph node tumors were divided into the CR of axillary lymph nodes (apCR) group and the non-CR of axillary lymph nodes (non-apCR) group according to the remission rates. Age, body mass index (BMI), menarche age, menstrual status, clinical tumor stage (cT), ER, PR, HER2, Ki67, and pCR were collected.
Data were statistically analyzed using the SPSS 26.0
statistical software (IBM Corp, Armonk, NY, USA). Clinical molecular
characteristics and related factors of the treatment response of the primary
tumor and axillary lymph node metastasis were compared among the HER2-negative
breast cancer subgroups using the
In this study, 185 patients with HER2-negative breast cancer and axillary lymph node metastasis were enrolled. In 23 patients, primary tumors and axillary lymph node metastasis achieved CR. In 13 patients, only primary tumors achieved CR, and in 24 patients, only axillary lymph node metastasis achieved CR (Table 1).
Characteristic | Total population, n (%) | |
Age | 29 (15.68%) | |
40–60 | 117 (63.24%) | |
39 (21.08%) | ||
BMI (Kg/m |
89 (48.11%) | |
96 (51.89%) | ||
Menarche age | 42 (22.70%) | |
14–16 | 112 (60.54%) | |
31 (16.76%) | ||
Menstrual status | Premenopausal | 91 (49.19%) |
Postmenopausal | 94 (50.81%) | |
cT | T1 | 24 (12.97%) |
T2 | 88 (47.57%) | |
T3 | 40 (21.62%) | |
T4 | 33 (17.84%) | |
ER status (biopsy) | Negative | 41 (22.16%) |
Low-Positive (1–10%) | 11 (5.95%) | |
High-Positive ( |
133 (71.89%) | |
PR status (biopsy)* | Negative | 64 (34.59%) |
Low-Positive (1–20%) | 43 (23.24%) | |
High-Positive ( |
78 (42.16%) | |
HER2 (biopsy) | IHC0 | 66 (35.68%) |
IHC1+ | 87 (47.03%) | |
IHC2+/ISH– | 32 (17.30%) | |
Ki67 expression (biopsy) | 12 (6.49%) | |
15–30% | 67 (36.22%) | |
106 (57.30%) | ||
PCR | aPCR | 24 (40.00%) |
bPCR | 13 (21.67%) | |
PCR | 23 (38.33%) | |
Note: *According to CSCO guidelines, PR20% serves as the threshold for Luminal A and Luminal B. |
There were 66 cases of IHC0, 87 cases of IHC1+, and 32 cases of IHC2+/ISH–.
There were no significant differences in age, BMI, menarche age, menstrual
status, cT, primary tumor treatment response, or axillary lymph node metastasis
treatment response among the HER2-negative subgroups. The differences in ER, PR,
and Ki67 among the three HER2-negative subgroups were statistically significant
(p
Characteristics | n | IHC0 | IHC1+ | IHC2+/ISH– | p | ||
age | 29 | 11 | 12 | 6 | |||
40–60 | 117 | 40 | 59 | 18 | |||
39 | 15 | 16 | 8 | 1.655 | 0.799 | ||
BMI (Kg/m |
89 | 29 | 43 | 17 | |||
96 | 37 | 44 | 15 | 0.843 | 0.656 | ||
Menarche age | 42 | 19 | 16 | 7 | |||
14–16 | 112 | 39 | 55 | 18 | |||
31 | 8 | 16 | 7 | 3.507 | 0.477 | ||
Menstrual status | Premenopause | 91 | 35 | 46 | 10 | ||
Postmenopausa | 94 | 31 | 41 | 22 | 4.982 | 0.083 | |
cT | T1 | 24 | 12 | 7 | 5 | ||
T2 | 88 | 27 | 49 | 12 | |||
T3 | 40 | 12 | 21 | 7 | |||
T4 | 33 | 15 | 10 | 8 | 10.265 | 0.114 | |
ER | Negative | 41 | 22 | 15 | 4 | ||
Positive | 144 | 44 | 72 | 28 | 7.728 | 0.021 | |
PR | Negative | 63 | 31 | 25 | 7 | ||
Positive | 122 | 35 | 62 | 25 | 8.112 | 0.017 | |
Ki67 | 19 | 5 | 5 | 9 | |||
15–30% | 60 | 18 | 36 | 6 | |||
106 | 43 | 46 | 17 | 17.774 | 0.001 | ||
Response of primary tumor | G1–G3 | 129 | 44 | 61 | 24 | ||
G4–G5 | 56 | 22 | 26 | 8 | 0.721 | 0.697 | |
Response of axillary lymph nodes | apCR | 47 | 18 | 21 | 8 | ||
Non-apCR | 138 | 48 | 66 | 24 | 0.198 | 0.906 |
Among the patients, there were 129 cases with a Miller–Payne grade of G1–G3 and 56 cases with a Miller–Payne grade of G4–G5.
There were no significant differences in age, BMI, menarche age, menstrual
status, cT, HER2, or ER among the groups based on the response of the primary
tumor to NAC. The differences in ER, PR, and Ki67 among the groups based on the
response of axillary lymph node metastasis to NAC were statistically significant
(p
Characteristics | n | G1–G3 | G4–G5 | p | ||
age | 30 | 18 | 12 | |||
40–60 | 116 | 83 | 33 | |||
39 | 28 | 11 | 1.607 | 0.448 | ||
BMI (Kg/m |
89 | 56 | 33 | |||
96 | 73 | 23 | 3.767 | 0.052 | ||
Menarche age | 42 | 29 | 13 | |||
14–16 | 112 | 74 | 38 | |||
31 | 26 | 5 | 3.656 | 0.161 | ||
Menstrual status | Premenopause | 76 | 55 | 21 | ||
Postmenopausa | 109 | 74 | 35 | 0.426 | 0.514 | |
cT | T1 | 24 | 12 | 12 | ||
T2 | 88 | 61 | 27 | |||
T3 | 40 | 28 | 12 | |||
T4 | 33 | 28 | 5 | 8.008 | 0.046 | |
HER2 | IHC0 | 66 | 44 | 22 | ||
IHC1+ | 87 | 61 | 26 | |||
IHC2+/ISH– | 32 | 24 | 8 | 0.721 | 0.697 | |
ER | Negative | 40 | 22 | 18 | ||
Positive | 145 | 107 | 38 | 5.246 | 0.022 | |
PR | Negative | 62 | 33 | 29 | ||
Positive | 123 | 96 | 27 | 12.034 | 0.001 | |
Ki67 | 79 | 66 | 13 | |||
106 | 63 | 43 | 12.466 | 0.000 | ||
Response of axillary lymph nodes | apCR | 47 | 18 | 29 | ||
Non-apCR | 138 | 111 | 27 | 29.491 | 0.000 |
Estrogen receptor, PR, Ki67, and the response of axillary lymph node metastasis
to NAC were included in the binary logistic regression for multivariate analysis.
The results revealed that there was a significant difference in the response of
axillary lymph node metastasis to NAC (p
Clinicopathological factors | B | SE | Wald | p | OR (95% CI) |
ER | –0.45 | 0.524 | 0.737 | 0.391 | 0.638 (0.228–1.781) |
PR | 0.802 | 0.454 | 3.127 | 0.077 | 2.230 (0.917–5.425) |
Ki67 | –0.731 | 0.422 | 2.996 | 0.083 | 0.482 (0.211–1.102) |
Response of axillary lymph nodes | 1.58 | 0.409 | 14.946 | 0.000 | 4.854 (2.179–10.814) |
There were 47 cases of apCR and 138 cases of non-apCR.
There were no significant differences in age, BMI, menarche age, menstrual
status, cT, and HER2 among the groups based on the response of axillary lymph
node metastasis to NAC, and the differences in ER, PR, and Ki67 among the groups
based on the response of the primary tumor to NAC were statistically significant
(p
Characteristics | n | apCR | Non-apCR | p | ||
age | 29 | 9 | 20 | |||
40–60 | 117 | 26 | 91 | |||
39 | 12 | 27 | 1.703 | 0.427 | ||
BMI(Kg/m |
89 | 23 | 66 | |||
96 | 24 | 72 | 0.017 | 0.895 | ||
Menarche age | 42 | 7 | 35 | |||
14–16 | 112 | 35 | 77 | |||
31 | 5 | 26 | 5.119 | 0.077 | ||
Menstrual status | Premenopause | 91 | 25 | 66 | ||
Postmenopausa | 94 | 22 | 72 | 0.404 | 0.525 | |
cT | T1 | 24 | 8 | 16 | ||
T2 | 88 | 26 | 62 | |||
T3 | 40 | 7 | 33 | |||
T4 | 33 | 6 | 27 | 3.820 | 0.282 | |
HER2 | IHC0 | 66 | 18 | 48 | ||
IHC1+ | 87 | 21 | 66 | |||
IHC2+/ISH– | 32 | 8 | 24 | 0.198 | 0.906 | |
ER | Negative | 41 | 20 | 21 | ||
Positive | 144 | 27 | 117 | 15.187 | 0.000 | |
PR | Negative | 63 | 27 | 36 | ||
Positive | 122 | 20 | 102 | 15.353 | 0.000 | |
Ki67 | 79 | 7 | 72 | |||
106 | 40 | 66 | 19.915 | 0.000 | ||
Response of primary tumor | G1–G3 | 129 | 18 | 111 | ||
G4–G5 | 56 | 29 | 27 | 29.491 | 0.000 |
Estrogen receptor, PR, Ki67, and the response of the primary tumor to NAC were
included in the binary logistic regression for multivariate analysis. The results
revealed that there were significant differences in Ki67 between the responses of
axillary lymph node metastasis to NAC and the responses of primary tumors to NAC
(p
Clinicopathological factors | B | SE | Wald | p | OR (95% CI) |
ER | –0.655 | 0.492 | 1.773 | 0.183 | 0.520 (0.198–1.362) |
PR | –0.446 | 0.463 | 0.930 | 0.375 | 0.640 (0.258–1.585) |
Ki67 | 1.273 | 0.483 | 6.950 | 0.008 | 3.571 (1.386–9.201) |
Response of primary tumor | 1.551 | 0.396 | 15.324 | 0.000 | 4.715 (2.169–10.250) |
In this study, ER, PR, and Ki67 were expressed differently in the three HER2-negative subgroups, and the negative-to-positive ratio of ER and PR decreased gradually in the IHC0, IHC1+, and IHC2+/ISH– subgroups. The negative-to-positive ratio of ER was 50.00%, 20.83%, and 14.29%, respectively, and the negative-to-positive ratio of PR was 88.57%, 40.32%, and 28.00%, respectively. In HER2-negative breast cancer, when the expression level of IHC increases, the positive rates of ER and PR increase.
Univariate analysis revealed that the efficacy of NAC for primary tumors might
be related to the tumor stage, ER, PR, Ki67, and the response of axillary lymph
node metastasis to NAC. The efficacy of NAC for axillary lymph node metastasis
may be related to ER, PR, Ki67, and the response of primary tumors to NAC.
Multivariate analysis revealed that Ki67 might be an independent factor affecting
the efficacy of NAC for axillary lymph node metastasis. A smaller tumor, negative
ER, negative PR, and a Ki67 level
The number of patients with breast cancer who receive neoadjuvant therapy is increasing [9]. Compared with adjuvant chemotherapy, NAC can dynamically monitor the drug sensitivity of tumors during chemotherapy, facilitate timely adjustment of drug dosage, and ensure the best curative effect of chemotherapy [10, 11]. In addition, NAC can reduce the clinical stage, increase the surgical resection and breast preservation rates, and greatly improve the quality of life and prognosis of patients. The five-year survival rate also significantly improves for patients who achieve pCR after NAC [12].
Breast cancer therapy enters a new level with ADC intervention. This treatment
produces exciting results not only in patients with HER2-positive breast cancer
but also in patients with low HER2 expression breast cancer [13, 14, 15, 16]. In this
study, gene expression analysis revealed that a low expression of HER2 exists in
luminal and non-luminal types of breast cancer, but ER is usually positive,
especially in the luminal B type [17]. According to immunohistochemical
expression levels, HER2-negative breast cancer can be subdivided into the IHC0,
IHC1+, and IHC2+/ISH– groups, while low HER2 expression groups include IHC1+ and
IHC2+/ISH– levels. We discovered differences in the clinical molecular
characteristics among the three subgroups that showed that the conditions of a
positive ER, positive PR, a Ki67 level
A previous study revealed that compared with zero HER2 expression, a low expression of HER2 was usually related to a higher histological grade and proliferation rate, and the prognosis was poorer [18, 19, 20, 21]. Recent data has revealed that the effective treatment rate of patients with HER2+ breast cancer was higher than that of patients with HER1+ breast cancer. Gentile et al. [22] established that there were no significant differences in age, histological grade, tumor size, lymph node status, and chemotherapy regimen between an effective and ineffective group. In unscreened invasive breast cancer, determining mass size under an ultrasound was a strong prognostic factor [23, 24]. In a study of women receiving NAC, determining tumor size under an ultrasound was not associated with metastasis-free survival, although there is evidence claiming that small tumors are more likely to achieve CR [25]. The Ki67 protein affects cell cycles and DNA synthesis, reflects the proliferation of tumor cells, and is also associated with the development and prognosis of breast cancer [26].
In this study, a smaller tumor, negative ER, negative PR, and a Ki67 level
HER2-negative breast cancer cannot be treated with targeted therapy, and the PCR rate of NAC is low, especially for hormone receptor-positive breast cancer. It is expected that early surgical or ADC intervention can help to achieve long-term benefits by screening patients with poor efficacy and poor prognosis through clinical analysis. However, this will require further study using a larger sample size.
Conception and design of the research—YZ, JPM. Acquisition of data—JPM, JHZ, TW, YM. Analysis and interpretation of the data—JPM, JZ. Statistical analysis—JPM. Obtaining financing—YZ. Writing of the manuscript—JPM, SF. Critical revision of the manuscript for intellectual content—HBW. All authors read and approved the final draft.
This study was conducted with approval from the Ethics Committee of Yantai Penglai People’s Hospital (202013). This study was conducted in accordance with the declaration of Helsinki. Written informed consent was obtained from all participants.
We would like to acknowledge the hard and dedicated work of all the staff that implemented the intervention and evaluation components of the study.
Scientific research project of Qingdao University Medical Group (No. YLJT20202020).
The authors declare no conflict of interest.