Estrogen receptor-negative and human epidermal growth factor receptor 2-negative breast cancer tissue have the highest Ki-67 labeling index and EGFR expression: gene amplification does not contribute to EGFR expression

Estrogen receptor (ER) and human epidermal growth factor 2 (HER2) are well-investigated molecules and the focus of many breast cancer therapies. There is a group of breast cancers lacking ER and HER2, but it is not fully understood. Treatment for these patients is limited to cytotoxic chemotherapy. The purpose of present study is to examine ER(-)/HER2(-) breast cancers, with a particular focus on epidermal growth factor receptor (EGFR). EGFR is a target molecule for which novel medicines have been recently developed for other organ cancers, however biological significance in breast cancer is not yet well demonstrated. Breast cancer specimens (n=58) were categorized into four groups: i) ER(+)/HER2(-) (51.7%); ii) ER(+)/HER2(+) (8.6%); iii) ER(-)/HER2(+) (20.7%); and iv) ER(-)/HER2(-) (19.0%). They were immunohistochemically (IHC) examined using antibodies for EGFR, platelet derived growth factor receptor (PDGFR)alpha, PDGFRbeta, parathyroid hormone (PTH) receptor, Ki-67, cyclinD1, p53, and vimentin. The Ki-67 labeling index (LI) was highest in ER(-)/HER2(-) (36.5%), and decreased in order from ER(-)/HER2(+) (31.4%), ER(+)/HER2(+) (17.7%), to (ER(+)/HER2(-) (15.9%) (p=0.001). EGFR, p53 and vimentin were highly expressed in ER(-)/HER2(-) breast cancer cells (p<0.01). CyclinD1 was inversely expressed to Ki-67 LI (p<0.001). Gene amplification of EGFR was examined by two in situ hybridization techniques, fluorescence in situ hybridization (FISH) and chromogenic in situ hybridization (CISH) in serial sections to IHC. Only 1 of 14 EGFR-positive breast cancers showed gene amplification at low levels by CISH. Overall, the ER(-)/HER2(-) breast cancer showed the highest Ki-67 LI, the most frequent expression of EGFR, p53 and vimentin, as well as the lowest expression of cyclinD1. It is unlikely that gene amplification contributes to EGFR expression. ER(-)/HER2(-) breast cancers have potential in the development of novel therapeutics, including targeted medicines.     

Tumor biology in estrogen receptor-positive,human epidermal growth factor receptor type 2-negative breast cancer: Mind the menopausal status

Breast cancer is not one disease, but can be categorized into four major molecular subtypes according to hormone receptor [estrogen receptor (ER) and progesterone receptor (PgR)] and human epidermal growth factor receptor type 2 (HER2) expression status. Ki67 labeling index and/or multigene assays are used to classify ER-positive, HER2-negative breast cancer into luminal A and luminal B (HER2-negative) subtypes. To date, most studies analyzing predictive or prognostic factors in ER-positive breast cancer have been performed in postmenopausal women, mainly using patients and samples in adjuvant aromatase inhibitor trials. In contrast, even the clinical roles of PgR and Ki67 have been little analyzed so far in premenopausal women. PgR is one of the estrogen-responsive genes, and it has been reported that plasma estradiol levels are related to expression levels of estrogen-responsive genes including PGR in ER-positive breast cancer. In this article, biological differences, especially differences in expression of PgR and Ki67 in ER-positive breast cancer between pre- and postmenopausal women are discussed. Clinical roles of PgR and Ki67 in ER-positive breast cancer differ between pre- and postmenopausal women. We suggest that the mechanisms of development and estrogen-dependent growth of ER-positive breast cancer might differ according to menopausal status.     

Ribociclib for the treatment of hormone receptor-positive,human epidermal growth factor receptor 2-negative advanced breast cancer

Introduction: The emergence of cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors marked a significant advancement in the treatment of advanced breast cancer. Ribociclib is an orally bioavailable, highly selective inhibitor of CDK4/6. In combination with various endocrine therapies, ribociclib has demonstrated clinical activity as a first-line therapy for patients with HR+, HER2? advanced breast cancer, without compromising the favorable toxicity profile associated with endocrine therapy. Thus, ribociclib is now considered a new standard of care for HR+, HER2? advanced breast cancer.

Areas covered: This review provides a concise overview of the preclinical and clinical development of ribociclib, including evidence of its clinical activity and safety profile when combined with endocrine therapy in HR+, HER2? advanced breast cancer.

Expert commentary: CDK4/6 inhibition represents a promising treatment option for patients with HR+ metastatic breast cancer. Ribociclib significantly improved progression-free survival in patients receiving first-line endocrine therapy for HR+, HER2? advanced breast cancer. Planned and ongoing trials investigating ribociclib in combination with other endocrine therapies and in various clinical settings will help to determine the optimal treatment sequence for different patient populations.     

Systemic therapy for hormone receptor-positive/human epidermal growth factor receptor 2-negative early stage and metastatic breast cancer

Hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer is defined by the presence of the estrogen receptor and/or the progesterone receptor and the absence of HER2 gene amplification. HR-positive/HER2-negative breast cancer accounts for 65%–70% of all breast cancers, and incidence increases with increasing age. Treatment varies by stage, and endocrine therapy is the mainstay of treatment in both early stage and late-stage disease. Combinations with cyclin-dependent kinase 4/6 inhibitors have reduced distant recurrence in the early stage setting and improved overall survival in the metastatic setting. Chemotherapy is used based on stage and tumor biology in the early stage setting and after endocrine resistance for advanced disease. New therapies, including novel endocrine agents and antibody-drug conjugates, are now changing the treatment landscape. With the availability of new treatment options, it is important to define the optimal sequence of treatment to maximize clinical benefit while minimizing toxicity. In this review, the authors first discuss the pathologic and molecular features of HR-positive/HER2-negative breast cancer and mechanisms of endocrine resistance. Then, they discuss current and emerging therapies for both early stage and metastatic HR-positive/HER2-negative breast cancer, including treatment algorithms based on current data.     

Differential effects of phorbol ester on epidermal growth factor receptors in estrogen receptor-positive and -negative breast cancer cell lines

A previous study from this laboratory (Koga et al., Cancer Res., 48: 2734-2739, 1988) demonstrated that the growth inhibitory effect of 1,25-dihydroxyvitamin D3 in human breast cancer cells in vitro was associated with a decline in the concentration of epidermal growth factor receptor (EGF-R). In the present study experiments were undertaken with the phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), an agent known to decrease EGF-R binding, in order to further define the relationship between changes in EGF-R binding and changes in growth rates in 10 human breast cancer cell lines. Treatment with TPA decreased the rate of cell proliferation in all cell lines except BT 474 in which a slight increase in proliferation rate was observed. Sensitivity to TPA was unrelated to estrogen receptor (ER) status and a wide spectrum of sensitivities was apparent. The concentrations of TPA that produced a 25% decrease in cell number ranged from less than 0.25 nM for MCF 7M and BT 20 cells to greater than 10 nM for the HBL 100, T 47D, and ZR 75-1 cell lines. Growth inhibition was associated with a block in cell cycle progression in the G1 and G2 + M phases of the cell cycle. In all cell lines studied, except BT 474, TPA treatment resulted in a reduction in the ability of cells to bind EGF. Saturation analysis revealed marked differences between the effects of TPA on EGF binding in ER+ and ER- cell lines. In ER+ cell lines, 2-h treatment with 10 nM TPA resulted in a marked reduction in the number of high affinity EGF-R sites and a significant decrease in binding affinity. Among this group of cell lines there was a significant positive correlation between the ability of TPA to decrease cell growth and the TPA-induced decrease in the number of EGF-R sites/cell (r = 0.82, P less than 0.03). In ER- cell lines, TPA-induced growth inhibition and the minor changes in EGF-R concentration were unrelated. However, growth inhibition was negatively correlated with TPA-induced changes in apparent affinity of the EGF-R (r = 1.00, P less than 0.003) and in the same rank order as the EGF-R concentration in control cells. These data demonstrate differential relationships between TPA-induced changes in growth and EGF-R binding in ER+ and ER- breast cancer cells, thus supporting the view that growth regulatory pathways are markedly different in these two subtypes of human breast cancer.     

Prognostic value of p53 expression in hormone receptor-positive and human epidermal growth factor receptor 2-negative breast cancer patients receiving neoadjuvant chemotherapy

Breast Cancer Research and Treatment - The aim of this study was to determine whether the outcome to neoadjuvant chemotherapy (NAC) can be predicted by analyzing p53 expression in hormone receptor...     

Thymidine labeling index and Ki-67 growth fraction in breast cancer: Comparison and correlation with prognosis

Summary In situ determination of proliferative activity was performed on 184 consecutive primary invasive breast cancers. Methods used were monoclonal antibody Ki-67 in immunohistochemistry and thymidine labeling index. Tumor proliferation correlated between both methods (p = 0.0001). For thymidine labeling index and Ki-67, respectively, significant correlations existed with histologic tumour grade and steroid hormone receptors (Tumor grade: TLIp = 0.0001; Ki-67 p = 0.0001. ER-ICA: TLI = 0.0001; Ki-67 p = 0.014. PgR-ICA: TLIp = 0.0001; Ki-67 p = 0.0008).For thymidine labeling index a significant correlation was demonstrated for overall survival (p = 0.001) and recurrence free survival (p = 0.01). No statistical significance was observed for clinical outcome and Ki-67 (overall survival p = 0.18; recurrence free survival p = 0.1). None of the factors, TLI or Ki-67, was an independent prognostic factor as demonstrated by multivariate analysis.     

Risk evaluation of early-stage hormone receptor-positive and human epidermal growth factor receptor 2-negative breast cancer patients: a population-based study from Taiwan

Breast Cancer Research and Treatment - To assess the prognostic value of the Dutch criteria for patients with early-stage hormone receptor-positive and human epidermal growth factor receptor...     

人表皮生长因子受体-2及雌激素受体与乳腺癌的关系

乳腺癌与人表皮生长因子受体-2及雌激素受体关系密切,这两种受体也是乳腺癌的分类标准和治疗靶点。在大多数乳腺癌患者中,人表皮生长因子受体-2信号途径和雌激素受体信号途径参与了细胞的增生存活过程。而且在乳腺癌病例中,人表皮生长因子受体-2和雌激素受体呈现出一定程度的负相关。这说明这两种受体活化后有一些联系。本文简要综述了人表皮生长因子受体-2和雌激素受体的联系以及这种联系在乳腺癌治疗中的意义。     

Clinicopathological factors predicting early and late distant recurrence in estrogen receptor-positive,HER2-negative breast cancer

Background

Most studies analyzing prognostic factors for late relapse have been performed in postmenopausal women who received tamoxifen or aromatase inhibitors as adjuvant endocrine therapy for estrogen receptor (ER)-positive breast cancer.

Methods

A total of 223 patients (108 premenopausal and 115 postmenopausal) with early distant recurrence and 149 patients (62 premenopausal and 87 postmenopausal) with late distant recurrence of ER-positive, HER2-negative breast cancer who were given their initial treatment between 2000 and 2004 were registered from nine institutions. For each late recurrence patient, approximately two matched control patients without relapse for more than 10 years were selected. Clinicopathological factors and adjuvant therapies were compared among the three groups by menopausal status and age.

Results

Factors predicting early recurrence in premenopausal women were large tumor size, high lymph node category and high tumor grade, whereas predictors for late recurrence were large tumor size and high lymph node category. In postmenopausal women under 60 years of age, factors predicting early recurrence were bilateral breast cancer, large tumor size, high lymph node category, low PgR expression and high Ki67 labeling index (LI), while predictors for late recurrence were large tumor size and high lymph node category. On the other hand, in postmenopausal women aged 60 years or older, factors predicting early recurrence were bilateral breast cancer, large tumor size, high lymph node category, high tumor grade, low ER expression and high Ki67 LI, whereas predictors for late recurrence were high lymph node category, low ER expression and short duration of adjuvant endocrine therapy.

Conclusion

Predictors of early and late distant recurrence might differ according to menopausal status and age.

     

The functional relationship between in vivo bromodeoxyuridine labeling index and Ki-67 proliferation index in human breast cancer

Proliferation indices are used, along with other parameters, to estimate the risk of recurrence of breast cancer for individual patients. Because it is unlikely one index will be practical for all patients, it is important to understand the relationship between various indices of proliferation. For this reason, we compared a proliferation index based on in vivo labeling of S-phase tumor cells with the thymidine analog bromodeoxyuridine (BrdUrd), to a proliferation index based on an estimate of the growth fraction with the MIB-1 antibody to the Ki-67 antigen. With informed consent, we gave 145 patients 200 mg/m² BrdUrd intravenously just prior to surgical removal of breast cancer. On histology sections, we visually counted S-phase cells which had incorporated BrdUrd using the Br-3 antibody which is specific to DNA-incorporated BrdUrd, and we counted cells in the growth fraction using the MIB-1 antibody to the Ki-67 antigen. We found that both indices were positively correlated with tumor size, number of positive nodes, and tumor grade, and both were negatively correlated with age and estrogen-progesterone receptor positivity. Using a linear functional relationship model, we found that the best (i.e. the maximal) fit between the two indices (correlation coefficient 0.79; p < 0.0001) occurred when each index was square root transformed, as is appropriate when counts follow a Poisson distribution. When we used the median as a cutpoint for each index, the classification of 19 percent of data pairs changed depending upon which index was used. We also estimated that the Ki-67 intercept (1.02 ± 0.25) was significantly greater than zero. We conclude that the BrdUrd index of DNA synthesis in S-phase correlates highly with the MIB-1 index of the growth fraction, and both indices correlate well with other parameters of tumor aggressiveness. Because this correlation is driven by concordance of the extremes of high and low counts, clinical comparison will be necessary to determine which is the better prognostic marker for human breast cancer.     

Relationship between epidermal growth factor receptor status and various prognostic factors in human breast cancer

Relationship between epidermal growth factor receptor (EGFR) status and various prognostic factors was investigated in 91 human breast cancer tissues. Epidermal growth factor receptor was measured by biochemical competitive binding assay using iodine 125 epidermal growth factor (125I)-EGF. The EGFR status was not correlated with axillary lymph node involvement, tumor size, stage, and histologic type, but significantly correlated with histologic grading (P less than 0.05) and lymphatic invasion (P less than 0.01). Between EGFR and estrogen receptor (ER) status, a clear inverse relationship was observed (P less than 0.01). The Ki-67-positive stained cell rate, which reveals the proportion of cycling cells, was significantly higher in EGFR-positive tumor tissues than in EGFR-negative cases. Furthermore, preliminary postoperative survey demonstrated a high tendency of recurrence rate of patients with EGFR-positive tumors as compared with those with EGFR-negative tumors. These data suggest that EGFR status may be important for the prediction of biologically high malignant potential.     

Prognostic significance of geminin expression levels in Ki67-high subset of estrogen receptor-positive and HER2-negative breast cancers

Background

Indication for chemotherapy in estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancers is determined on the basis of Ki67 expression level. However, since Ki67-high cancers are not necessarily sensitive to chemotherapy, identification of such patients who do not need chemotherapy is an important issue.

Patients and methods

We used immunohistochemical staining to examine the expression levels of ER, progesterone receptor (PgR), Ki67, and geminin, a marker of S to G2/M phases, in 80 ER-positive/HER2-negative breast cancers. The labeling indices of Ki67 and geminin were determined and cutoff values were set at 15 and 6 %, respectively.

Results

Ki67 and geminin expression levels were significantly associated with nuclear grade. In the Ki67-low subset, 26 out of 28 (92.9 %) cancers were geminin low and in the Ki67-high subset, 31 out of 52 (59.6 %) were geminin high. Distant disease-free survival (DDFS) of the geminin-high subset was significantly poorer than that of the geminin-low subset (P = 0.009). In the Ki67-low subset, only one patient showed recurrence. Metastasis was detected in eight out of 31 (25.8 %) patients in the geminin-high group of the Ki67-high subset, but no recurrence was observed in the geminin-low group of the Ki67-high subset.

Conclusion

Geminin-high breast cancers are significantly associated with worse prognosis. Since poorer prognosis was recognized only in the geminin-high group in Ki67-high cancers, we speculate that geminin may be useful for identifying patients in the Ki67-high subset who can avoid unnecessary chemotherapy.

     

Secreted growth factors from estrogen receptor-negative human breast cancer do not support growth of estrogen receptor-positive breast cancer in the nude mouse model

Estrogen receptor (ER)-negative MDA-231 human breast cancer cells have been shown to secrete high concentrations of several growth factors including transforming growth factor-alpha and insulin-like growth factor I, which could have important autocrine or paracrine growth regulatory functions and, additionally, could explain the rapid autonomous growth of these cells. In contrast, the hormone-responsive, ER-positive MCF-7 cells secrete low levels of these factors constitutively. Since estrogen treatment increases secretion of these growth factors in MCF-7 cells, it has been postulated that these growth factors mediate estrogen's growth effects through an autocrine mechanism. To test this hypothesis we reasoned that growth factors supplied by MDA-231 cells should support growth of MCF-7 cells in an estrogen-depleted environment. Inoculation of castrated female athymic nude mice with MDA-231 cells resulted in rapid tumor growth. However, MDA-231 tumors did not support growth of MCF-7 cells inoculated on the opposite flank by an endocrine mechanism; MCF-7 tumors required estrogen supplementation for growth. To determine if MDA-231 cells could support MCF-7 growth by a paracrine mechanism, various mixtures of the two cell lines were coinoculated at the same site in castrated or in estrogen-supplemented mice. ER was not detectable in tumors derived from a mixed inoculum, indicating the absence of MCF-7 cell growth. Furthermore, DNA flow cytometry of these tumors revealed only a single G₁ peak representative of MDA-231 cells in estrogen-deprived mice. On the other hand, two distinct G₁ peaks representing both MDA-231 and MCF-7 cells were detected in tumors grown in estrogen-supplemented mice. These data demonstrate that growth factors from estrogen-independent MDA-231 cells are not capable of replacing estrogen for growth stimulation of MCF-7 cells. Either estrogen-stimulated growth of MCF-7 cells requires other secreted factors not supplied by MDA-231 cells, or it involves a different mechanism.     

乳腺癌彩色多普勒血流成像与雌激素受体、人表皮生长因子受体2、p53和Ki-67的相关性分析

目的 分析乳腺癌彩色多普勒血流成像(CDFI)特征与雌激素受体(ER)、人表皮生长因子受体2(HER2)、p53及Ki-67的相关性.方法 分析76例乳腺癌患者的CDFI特征(肿瘤直径、边缘毛刺征、微钙化、血流分级、淋巴结转移、后方回声衰减),并采用Spearman法分析乳腺癌CDFI特征与ER、HER2、p53及Ki-67的相关性.结果 乳腺癌患者乳腺癌组织中ER、HER2、p53及Ki-67阳性表达率分别为73.68％(56/76)、60.53％(46/76)、48.68％(37/76)、40.79％(31/76),其中ER阳性表达率最高,Ki-67阳性表达率最低.有边缘毛刺征、血流分级为0～1级、有淋巴结转移的乳腺癌患者乳腺癌组织中ER阳性表达率均高于无边缘毛刺征、血流分级为2～3级、无淋巴结转移者(P﹤0.05).有微钙化、血流分级为2～3级、有淋巴结转移的乳腺癌患者乳腺癌组织中HER2阳性表达率均高于无微钙化、血流分级为0～1级、无淋巴结转移者(P﹤0.05).血流分级为2～3级、有淋巴结转移的乳腺癌患者乳腺癌组织中p53及Ki-67阳性表达率均高于血流分级为0～1级、无淋巴结转移者(P﹤0.05).乳腺癌患者乳腺癌组织中ER阳性表达率与肿瘤边缘毛刺征、淋巴结转移均呈正相关(P﹤0.05),与血流分级呈负相关(P﹤0.05),而与肿瘤直径、微钙化、后方回声衰减均无相关性(P﹥0.05).乳腺癌患者乳腺癌组织中HER2阳性表达率与肿瘤微钙化、血流分级、淋巴结转移均呈正相关(P﹤0.05),而与肿瘤直径、边缘毛刺征、后方回声衰减均无相关性(P﹥0.05).乳腺癌患者乳腺癌组织中p53、Ki-67阳性表达率与血流分级、淋巴结转移均呈正相关(P﹤0.05),而与肿瘤直径边缘毛刺征、微钙化、后方回声衰减均无相关性(P﹥0.05).结论 乳腺癌患者CDFI特征与ER、HER2、p53及Ki-67阳性表达存在一定的相关性,在预测乳腺癌生物学特性中具有一定的指导价值.     

Utility of the CPS + EG staging system in hormone receptor-positive,human epidermal growth factor receptor 2-negative breast cancer treated with neoadjuvant chemotherapy

BackgroundPathologic complete response after neoadjuvant chemotherapy (NACT) correlates with overall survival (OS) in primary breast cancer. A recently described staging system based on pre-treatment clinical stage (CS), final pathological stage (PS), estrogen receptor (ER) status and nuclear grade (NG) leads to a refined estimation of prognosis in unselected patients. Its performance in luminal type breast cancers has not been determined. This study investigates the clinical utility of this CPS + EG score when restricted to hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2–) patients and compares the results to a cohort of unselected patients.MethodsThe CPS + EG score was calculated for 6637 unselected patients and 2454 patients with HR + /HER2− tumours who received anthracycline/taxane-based NACT within 8 prospective German trials.ResultsFive-year disease-free survival (DFS) and OS were 75.6% and 84.1% for the unselected cohort and 80.6% and 87.8% for the HR + /HER2− subgroup, respectively. The CPS + EG system distinguished different prognostic groups with 5-year DFS ranging from 0% to 91%. The CPS + EG system leads to an improved categorisation of patients by outcome compared to CS, PS, ER or NG alone. When applying the CPS + EG score to the HR + /HER2− subgroup, a shift to lower scores was observed compared to the overall population, but 5-year DFS and OS for the individual scores were identical to that observed in the overall population.ConclusionsIn HR + /HER2− patients, the CPS + EG staging system retains its ability to facilitate a refined stratification of patients according to outcome. It can help to select candidates for post-neoadjuvant clinical trials in luminal breast cancer.     

Microtubule disruption induced by estradiol in estrogen receptor-positive and -negative human breast cancer cell lines

Effects of estrogens on the cytoplasmic microtubule networkwere examined by the indirect immunofluorescence method usinganti-ß-tubulin antibody. Estradiol, a naturally occurringestrogen, decreased the amount of cytoplasmic microtubule fibersduring interphase in the human breast cancer cell lines MCF-7and MDA-MB-231. Since MDA-MB-231 is an estrogen receptor-negativecell line, estradiol-induced microtubule disruption seems tobe independent of estradiol binding to receptors. The effectiveconcentration of estradiol required for induction of microtubuledisruption in 50% of the cells (EC₅₀) was 81 µM for MCF-7cells and 82 µM for MDA-MB-231 cells. A synthetic estrogen,diethylstilbestrol, also induced a decrease in microtubule fibers,with an EC₅₀ value of 48 µM for MCF-7 cells and 50 µMfor MDA-MB-231 cells. When estrogentreated and microtubule-depolymerizedcells were washed and the medium was replaced with fresh, intracellularmicrotubule networks reappeared within 3 h. When MCF-7 cellswere cultured for 4 days with estradiol (50 µM), cellgrowth was completely inhibited. However, estrone affected themicrotubule network and cell proliferation only slightly. Theseresults suggest that estradiol-induced microtubule disruptionis closely related to its inhibitory effect on cell growth.     

Prognostic value of Ki-67 labeling index in patients with node-negative, triple-negative breast cancer

The aim of this analysis was to investigate the usefulness of Ki-67 labeling index (LI) for the identification of different prognostic subgroups in primary node-negative, triple negative breast cancer (TNBC) patients. From January 1997 to December 2005, 1,053 patients operated for TNBC were identified through the institutional clinical database. The study was performed in accordance with REMARK criteria. The relationship between Ki-67LI and the risk of breast-related deaths was evaluated with a multivariable Cox regression model. Cubic splines were used to model Ki-67LI as a continuous variable. We selected 496 consecutive patients with node-negative TNBC. Median age was 52 years, median Ki-67LI 48% (range 4-95), and median follow up 6 years (range 0.5-13). Total deaths and deaths from BC were 52 (10.5%) and 38 (7.7%), respectively. Ki-67LI increased with decreasing age (P<0.01), increasing tumor size (P<0.01), and grade (P<0.01). When analyzing Ki-67LI as a continuous variable, the risk of death from BC increased steeply with increasing Ki-67LI up to about 35% and remained flat for higher values (adjusted effect of Ki-67 P=0.049; adjusted nonlinear effect P=0.021). Accordingly, when dividing patients into lower (≤35%) and higher (>35%) Ki-67LI subgroups, the 5-year cumulative incidence of breast-related deaths were 2.3 and 9.0%, respectively, with an adjusted HR(>35 vs ≤35) of 2.3 (95% CI 1.0-5.8, P=0.046). Within the group of patients with node-negative TNBC, Ki-67LI was associated with different prognoses subgroups. Ki-67LI might be useful in the design of trials of risk-adapted adjuvant therapies.