Omission of radiotherapy in elderly women with early stage metaplastic breast cancer

PurposeMultiple studies have evaluated the omission of radiation therapy (RT) in elderly women with invasive carcinoma; no studies to date have assessed this question for metaplastic breast cancer (MBC). This study is the only known study describing national practice patterns and addressing the impact of RT versus observation on survival in elderly women with T1-2N0 MBC.MethodsThe National Cancer Data Base was queried (2004–2013) for women aged ≥70 years with T1-T2N0 MBC that underwent lumpectomy. Multivariable logistic regression ascertained factors associated with RT administration. Kaplan-Meier analysis evaluated overall survival (OS) between patients treated with or without postoperative RT. Cox proportional hazards modeling determined variables associated with OS. Propensity matching was performed in order to address indication bias.ResultsOf 547 total patients, 176 (32%) underwent observation, and 371 (68%) received postoperative RT. Temporal trends revealed that withholding RT steadily declined over the studied time period. RT delivery was less likely in patients not undergoing hormonal therapy or those ≥80 years old. In both the overall population and following propensity matching, delivery of RT was associated with higher OS (p < 0.001 for both). On Cox multivariate analysis, poorer OS was independently associated with advancing age, higher T stage, high-grade disease, and omitting postoperative RT (p < 0.05 for all).ConclusionsAlthough level I evidence exists to omit RT in select elderly women, this is the only study evaluating this notion for MBC. These results do not support the routine withholding of RT in T1-2N0 MBC owing to the independent association with worse survival.     

Outcomes of systemic therapy for advanced triple-negative breast cancer: A single centre experience

BackgroundPrognosis is worse for advanced triple-negative breast cancer (aTNBC) compared to other disease subtypes. Trials describe treatment outcomes in single specified lines of therapy; but few data describe treatment outcomes across the whole treatment pathway, which is critical in determining when patients should be referred for trials and to inform discussion. We evaluated treatment outcomes for aTNBC (overall response rate [ORR], median progression-free survival [mPFS] and median overall survival [mOS]) in patients treated largely outside of clinical trials.MethodsWe retrospectively identified 268 patients diagnosed with aTNBC from 01/12/2011 to 30/11/2016 from our electronic records and recorded patients' and tumour characteristics and treatment outcomes. Chi-squared/Fishers exact test and Kaplan-Meier statistical methods were utilised.Results186 patients treated with ≥1 line of systemic treatment were eligible and had median age of 55 (range 26–91). 53.8% had ECOG Performance Status 0 and 69.9% visceral involvement. 38.6% had disease-free interval (DFI)≤12 months following surgery or adjuvant chemotherapy completion and 14.0% had de-novo advanced disease. 11.4% carried a BRCA mutation. 64.5% received two lines of therapy, 37.6% three and 21.5% four.ORR and mPFS were 43.9% and 3.7 months for first-line therapy, 40.2% and 3.5 months for second-line, 28.8% and 2.5 months for third-line and 25.0% and 2.1 months for fourth-line. In first line, DFI>12 months was associated with higher ORR and longer PFS compared DFI ≤12 months.ConclusionsThe observed response rates are consistent with literature. However, PFS is short, and early consideration of clinical trials can be justified in these patients.     

Presentation and survival by hormonal receptor status in metaplastic breast cancer: A propensity score-matched analysis

BackgroundMetaplastic breast cancer (MBC) is a rare and aggressive form of breast cancer. The effectiveness of chemotherapy (CT) for MBC remains controversial. The present study aimed to evaluate the efficacy of CT combined hormone receptor (HR) status on MBC patients with high risk (T1-4N2-3M0 and T4N0-1M0) by propensity-score matching (PSM).MethodsA retrospective study was performed to analyze MBC from the SEER database. Breast cancer-specific survival (BCSS) was analyzed using the Kaplan–Meier curve. Cox proportional hazard models were used to assess BCSS. PSM was used to make 1:1 case-control matching.ResultsThis study identified 3116 patients. The median follow-up time was 44 months (range, 1–321 months). About 62.5 % of patients received CT. 23.0 % of patients were HR-positive. Recurrence risk had a significant difference between the HR-negative and HR-positive groups. In the multivariable Cox regression model, CT had no benefit for MBC patients. HR status was not associated with a better prognosis. In subgroup analysis, the Kaplan–Meier analysis showed that HR-negative MBC with intermediate-risk benefited from CT. For HR-positive MBC, patients with intermediate and high risk also benefited from CT. After PSM, neither CT nor HR status was not related to better BCSS. Moreover, the use of CT could only improve the survival of HR-positive MBC patients with high risk.ConclusionPSM analysis showed that HR status was not associated with a better prognosis. CT was not a significant prognostic factor for prognosis. However, HR-positive MBC patients with high risk might benefit from CT.     

Omitting radiation therapy in women with triple-negative breast cancer leads to worse breast cancer-specific survival

PurposeTo examine locoregional recurrence (LRR) and breast cancer-specific survival (BCSS) after breast-conserving therapy (BCT) or mastectomy (ME) with or without radiation therapy (RT) in triple-negative breast cancer (TNBC).Material & MethodsWe identified non-metastatic TNBC cases from a single institution database. BCT, ME with RT (ME + RT) and ME only were compared with respect to LRR and BCSS. Cox regression models were used to analyze the association between prognostic factors and outcome.Results439 patients fulfilled the inclusion criteria. Median follow-up was 10.2 years (interquartile range 7.9; 12.4 years). Patients in the BCT (n = 239), ME + RT (n = 116) and ME only (n = 84) group differed with respect to age, pT, pN, lymphovascular invasion, lymph node dissection and chemotherapy administration. Ten-year LRR rates were seven percent, three percent and eight percent for the BCT, ME + RT and ME only group, respectively. pN was associated with LRR. In multivariable analysis LRR were significantly lower in the ME + RT group compared to the BCT and the ME only group (p 0.037 and 0.020, respectively).Ten year BCSS was 87%, 84% and 75% for the BCT, ME + RT and ME only group, respectively. pT, pN, lymph node dissection, lymphovascular invasion and the administration of chemotherapy were associated with BCSS. In multivariable analysis BCSS was significantly lower in the ME only group compared to the BCT group and the ME + RT group (p 0.047 and 0.003, respectively).ConclusionTNBC patients treated with ME without adjuvant RT showed significant lower BCSS compared to patients treated with BCT or ME + RT and significant more LRR compared to ME + RT when corrected for known clinicopathological prognostic factors.     

Prospective comparison of outcome after treatment for triple-negative and non-triple-negative breast cancer

Introduction

Triple-negative breast cancers (TNBC) are associated with a poor prognosis owing to an aggressive phenotype. We aimed to carry out a prospective study comparing management strategies and response to therapy in TNBC and non-TNBC patients.

The impact on clinical outcomes of post-operative radiation therapy delay after neoadjuvant chemotherapy in patients with breast cancer: A multicentric international study

IntroductionRadiation therapy (RT) is frequently used for post-operative treatment in breast cancer (BC) patients who received preoperative systemic therapy (PST) and surgery. Nevertheless, the optimal timing to start RT is unclear.Material and methodsData from BC patients who underwent chemotherapy as PST, breast surgery and RT at 3 Institutions in Brazil and Canada from 2008 to 2014 were evaluated. Patients were classified into three groups regarding to the time to initiation of RT after surgery: <8 weeks, 8–16 weeks and >16 weeks.ResultsA total of 1029 women were included, most of them (59.1%; N = 608) had clinical stage III. One hundred and forty-one patients initiated RT within 8 weeks, 663 between 8 and 16 weeks and 225 beyond 16 weeks from surgery. With a median follow-up of 32 months, no differences in disease-free survival (DFS), overall survival and locoregional recurrence-free survival (LRRFS) were observed of time to indicated RT (<8 weeks versus 8–16 weeks versus >16 weeks). However, in luminal subtype patients (46.5%; N = 478), initiation of RT up to 8 weeks after surgery was associated with better LRRFS (<8 weeks versus >16 weeks: HR 0.22; 95%CI 0.05–0.86; p = 0.03), with a tendency to a better DFS (<8 weeks versus >16 weeks: HR 0.50; 95%CI 0.25–1.00).ConclusionRT initiated up to 8 weeks after surgery was related to better LRRFS in luminal BC patients who underwent PST. Our results suggest that early start of RT is important for these patients.     

Radiotherapy in the treatment of breast cancer: a personal retrospective

Allan Langlands commenced training as a radiation oncologist in 1960 and has continued to treat patients with breast cancer for over 30 years. Moved to Westmead Hospital in Sydney he played a role in the development of radiation oncology in Australia. With an extensive research record (authoring over 200 peer-reviewed papers) this article reflects the changes in breast cancer treatment which have occurred over this period. The incorporation of evidence from the clinical trials in breast cancer management, changes in radiation therapy techniques and incorporation of patient choice in treatment decisions are discussed.     

“三阴”乳腺癌新辅助化疗前后BCSG1基因状况研究

目的 探讨乳腺癌特异基因（BCSG1）在“三阴”性乳腺癌新辅助化疗疗效评估中的价值。方法采用免疫组化S．P法和荧光定量PCR方法检测32例“三阴”性乳腺癌患者新辅助化疗（CEF方案）前后乳腺癌组织BCSG1的表达,比较化疗前后肿瘤体积的变化情况,分析新辅助化疗前后BCSG1蛋白表达与肿瘤形态学变化的关系。结果23例乳腺癌患者新辅助化疗后肿瘤体积均有明显缩小,病灶缓解率（CR＋PR）为84．4％;新辅助化疗后BCSG1mRNA表达水平亦明显低于化疗前（P〈O．05）,BCSG1蛋白高表达率低于新辅助化疗前（P〈0．01）。结论BCSG1分子和蛋白水平在“三阴”性乳腺癌新辅助化疗后均明显降低,与新辅助化疗后疗效呈负相关（r=-0．584,P〈0．01）,提示BCSG1可作为“三阴”乳腺癌新辅助化疗疗效的预测因子。     

三阴性乳腺癌的临床病理特征分析

目的探讨三阴性乳腺癌(TNBC)的临床病理特征。方法回顾性分析4年间资料完整的3 8例TNBC患者临床资料,包括患者的一般状况、病理特点、分子标志物、复发与转移状况,并与同期非TNBC进行比较。结果≤35岁的患者在TNBC及非TNBC中分别占21.05%(8/38)和5.14%(15/292)(P<0.05)。TNBC组中有淋巴结转移者60.53%(23/38),高于非TNBC的43.49%(127/292)(P<0.05),TNBC组中组织学III级者52.63%(20/38)高于非TNBC组的35.27%(103/292)(P<0.05),TNBC中有瘤周脉管侵犯者占31.58%(12/38)高于非TNBC的15.41%(45/292)(P<0.05)。TNBC组表皮生长因子受体(EGFR)阳性率、血管内皮生长因子(VEGF)阳性率、E-钙黏附蛋白(E-cad)异常表达率分别为81.58%(31/38),78.95%(30/38),65.79%(25/38),高于非TNBC组的39.73%(116/292),61.30%(179/292),48.29%(141/292)(均P<0.05)。远处转移率在TN...     

Omission of chemotherapy for low-grade,luminal A N1 breast cancer: Patterns of care and clinical outcomes

PurposeMultiple ongoing randomized studies are assessing the impact of omission of chemotherapy (CT) in low-risk node-positive Luminal A breast. The goal of this investigation was to evaluate trends and practice patterns of adjuvant CT use in Luminal A pT1-3N1 breast cancer, along with determining the clinical benefit from adjuvant CT in this patient population.MethodsThe National Cancer Data Base was queried (2004–2014) for women with pT1-3N1 luminal A invasive ductal carcinoma receiving adjuvant hormonal therapy (HT). Multivariable logistic regression ascertained factors associated with adjuvant CT administration. Kaplan-Meier analysis evaluated overall survival (OS) between patients treated with CT/HT vs. HT alone, while sub-stratifying patients by age.ResultsOf 8548 total patients, 5182 (61%) received CT/HT, while 3366 (39%) received HT alone. A steady rise in omission of adjuvant CT was observed, from 14% (2004–2005) to 41% (2012–2014). A decision not to use CT was more likely in more recent time periods, in older patients, at academic centers, following lumpectomy, and with lower T classification (p < 0.05 for all). CT was associated with higher OS in all patients (p < 0.001) and women ≤50 years old (p = 0.030), but not for ages 51–60 (p = 0.116), 61–70 (p = 0.222), or >70 (p = 0.239).ConclusionsUsing CT for Luminal A N1 breast cancer is decreasing over time, primarily in older patients and at academic centers. Although CT is still associated with an OS advantage in all patients, subgroup analysis demonstrated no OS benefit in women >50 years of age. These results have implications on the ongoing randomized trials.     

Neoadjuvant therapy in triple-negative breast cancer: A systematic review and network meta-analysis

BackgroundEvidence for the preferred neoadjuvant therapy regimen in triple-negative breast cancer (TNBC) is not yet established.MethodsLiterature search was conducted from inception to February 12, 2022. Phase 2 and 3 randomized controlled trials (RCTs) investigating neoadjuvant therapy for TNBC were eligible. The primary outcome was pathologic complete response (pCR); the secondary outcomes were all-cause treatment discontinuation, disease-free survival or event-free survival (DFS/EFS), and overall survival. Odd ratios (OR) with 95% credible intervals (CrI) were used to estimate binary outcomes; hazard ratios (HR) with 95% CrI were used to estimate time-to-event outcomes. Bayesian network meta-analysis was implemented for each endpoint. Sensitivity analysis and network meta-regression were done.Results41 RCTs (N = 7109 TNBC patients) were eligible. Compared with anthracycline- and taxane-based chemotherapy (ChT), PD-1 inhibitor plus platinum plus anthracycline- and taxane-based ChT was associated with a significant increased pCR rate (OR 3.95; 95% CrI 1.81–9.44) and a higher risk of premature treatment discontinuation (3.25; 1.26–8.29). Compared with dose-dense anthracycline- and taxane-based ChT, the combined treatment was not associated with significantly improved pCR (OR 2.57; 95% CrI 0.69–9.92). In terms of time-to-event outcomes, PD-1 inhibitor plus platinum plus anthracycline- and taxane-based ChT was associated with significantly improved DFS/EFS (HR 0.42; 95% CrI 0.19–0.81).ConclusionsPD-1 inhibitor plus platinum and anthracycline- and taxane-based ChT was currently the most efficacious regimen for pCR and DFS/EFS improvement in TNBC. The choice of chemotherapy backbone, optimization of patient selection with close follow-up and proactive symptomatic managements are essential to the antitumor activity of PD-1 inhibitor.     

Noncompliance with adjuvant radiation, chemotherapy, or hormonal therapy in breast cancer patients

INTRODUCTION: There is little information on patient-driven noncompliance of adjuvant therapies and its consequences. METHODS: This retrospective study compares clinical, pathological features and outcomes of breast cancer patients who were compliant to recommended radiation, chemotherapy, and hormonal therapies to those who were noncompliant. RESULTS: Noncompliance rates for chemotherapy, radiation, and tamoxifen were 31 of 421 (7%), 30 of 855 (4%), and 294 of (37%) respectively. Old age was associated with noncompliance to chemotherapy and radiation, but younger women tend to be more often noncompliant to tamoxifen. Noncompliance with chemotherapy or radiation did not significantly affect 5-year local and distant disease-free survival rates. Noncompliance with tamoxifen was associated with decreased 5-year local and distant disease-free survivals (87% versus 96%, 76% versus 87%, respectively, P < .001). CONCLUSION: Noncompliance with tamoxifen is the most common, resulting in significantly increased risk of local and distant disease recurrence.     

Lymphocyte-predominant triple-negative breast carcinomas in premenopausal patients: Lower expression of basal immunohistochemical markers

ObjectivesTriple-negative breast carcinomas (TNBCs) correspond to a molecular heterogeneous disease defined by lack of estrogen and progesterone receptor expression, and the absence of overexpression and/or amplification of HER2. Recent data indicate that clinical outcome in TNBC is affected by tumor-infiltrating lymphocytes, suggesting that they can benefit from immunotherapies. We selected 116 consecutive premenopausal patients with TNBC to compare the immunohistochemical profile of the group rich in tumor-infiltrating lymphocytes with those without this characteristic.Materials and methodsWe reviewed all the original histological sections to assess pathological features, and to select a representative area for tissue microarrays and immunohistochemical study. Estrogen and progesterone receptors, HER2 and Ki-67 were evaluated in whole histological sections. The following markers were analyzed in tissue microarrays sections: androgen receptor, cytokeratin 5/6, cytokeratin 14, epidermal growth factor receptor (EGFR), vimentin, p16, claudin-3, -4, and -7, p63, and aldehyde dehydrogenase isoform 1 (ALDH1). Lymphocyte-predominant breast cancer (LPBC) was defined by the presence of more than 50% of lymphocytes in the intratumoral stroma.ResultsTwenty-six (22.4%) patients present tumors classified as LPBC and 90 (77.6%) as non-LPBC. The two groups were similar regarding age of patients, tumor grade and Ki-67 positive cells. LPBC cases presented lower frequency of expression of the basal cytokeratins, EGFR, and basal-like immunoprofile. There was a trend to higher expression of ALDH1 by stromal intratumoral cells. The expression of all other markers were similar in the two groups.ConclusionsLymphocyte-predominant TNBC in premenopausal patients are mostly of non-basal phenotype.     

表阿霉素联合多西紫杉醇新辅助化疗治疗三阴、非三阴乳腺癌的疗效及预后评价

目的比较表阿霉素联合多西紫杉醇新辅助化疗方案(ET方案)对三阴乳腺癌(TNBC)和非三阴乳腺癌(non-TNBC)的临床疗效及预后差别。方法回顾性分析接受ET新辅助化疗方案治疗的198例乳腺癌患者的临床资料,依据免疫组化结果将乳腺癌分为TNBC及non-TNBC两组,对两类乳腺患者接受ET新辅助化疗方案后的病理疗效及预后的差别进行分析比较。结果 198例乳腺癌患者中,TNBC43例,non-TNBC155例。所有患者的临床总有效率(cOR)为76.8%,其中完全缓解率24.7%,部分缓解率48.5%;TNBC患者的临床有效率84.2%,病理完全缓解率(pCR)27.9%;non-TNBC患者临床有效率70.4%,病理完全缓解率12.9%。TNBC患者与非TNBC患者5年无病生存率(DFS)分别为52.9%和70.9%(P<0.05);TNBC患者与非TNBC患者5年总体生存率分别为59.1%和80.5%(P<0.05)。结论表阿霉素联合多西紫杉醇新辅助化疗方案治疗三阴乳腺癌患者能够获得较好的临床效果。     

Radiation therapy utilization and outcomes for older women with breast cancer: Impact of molecular subtype and tumor grade

BackgroundRadiation therapy (RT) utilization for elderly women with respect to human epidermal growth factor receptor 2 (HER2) receptor status has not been evaluated. Our purpose was to determine differences in RT utilization and breast cancer specific survival (BCSS) for elderly breast cancer patients with distinct molecular biomarkers.MethodsThe Surveillance, Epidemiology, and End Results database was queried for women ≥70 years of age diagnosed with T1N0M0 breast cancer between 2010 and 2013 receiving breast conservation. Chi-squared analysis was performed to determine the difference in RT utilization between groups. Multivariable logistic regression analysis was performed to determine predictors for RT use. Kaplan-Meier curves were created and the log-rank test done to compare differences in breast cancer specific survival (BCSS) between groups.ResultsA total of 12,312 patients met the inclusion criteria. Receipt of RT for patients with distinct tumor biomarkers was as follows: 55.7% for patients with Estrogen Receptor (ER) +/HER2+; 57.1% for patients with ER+/HER2-; 65.6% for patients with ER-/HER2+; and 69.2% for ER-/HER2- patients (p < 0.001). Factors associated with RT use included ER-/HER2- status, 70–74 years of age, and high grade disease, while adjuvant RT was associated with improve BCSS in ER+/HER2- and ER-/HER2- patients.ConclusionsPatients 70–74 years old and those with ER-/HER2- are more likely to receive adjuvant RT. Moreover, adjuvant RT is associated with improvements in BCSS in ER+/HER2- and ER-/HER2- patients. Given possible poor compliance with hormonal therapy, the omission of RT in ER + patients, without consideration of HER2 status, should be undertaken with care.     

乳腺癌患者综合治疗后肺部早期放射性反应

作者总结了经过手术、放疗和化疗等综合治疗的６２例乳腺癌病例。化疗用ＣＭＦ或ＣＡＭＦ方案。肺部早期放射性反应的发生率为１１．３％（７例），而且早期肺放射性反应发生率均发生于含阿霉素的ＣＡＭＦ化疗方案病例中，说明阿霉素与放射治疗合并使用会增加早期肺放射性反应的发生率。因此，综合治疗中，为了既得到好的治疗效果又减少肺部早期放射性反应的发生，对于用阿霉素化疗的病例，我们应该适当控制总照射剂量，精确设计放射野。     

Changes in breast cancer management during the Corona Virus Disease 19 pandemic: An international survey of the European Breast Cancer Research Association of Surgical Trialists (EUBREAST)

BackgroundCorona Virus Disease 19 (COVID-19) had a worldwide negative impact on healthcare systems, which were not used to coping with such pandemic. Adaptation strategies prioritizing COVID-19 patients included triage of patients and reduction or re-allocation of other services. The aim of our survey was to provide a real time international snapshot of modifications of breast cancer management during the COVID-19 pandemic.MethodsA survey was developed by a multidisciplinary group on behalf of European Breast Cancer Research Association of Surgical Trialists and distributed via breast cancer societies. One reply per breast unit was requested.ResultsIn ten days, 377 breast centres from 41 countries completed the questionnaire. RT-PCR testing for SARS-CoV-2 prior to treatment was reported by 44.8% of the institutions. The estimated time interval between diagnosis and treatment initiation increased for about 20% of institutions. Indications for primary systemic therapy were modified in 56% (211/377), with upfront surgery increasing from 39.8% to 50.7% (p < 0.002) and from 33.7% to 42.2% (p < 0.016) in T1cN0 triple-negative and ER-negative/HER2-positive cases, respectively. Sixty-seven percent considered that chemotherapy increases risks for developing COVID-19 complications. Fifty-one percent of the responders reported modifications in chemotherapy protocols. Gene-expression profile used to evaluate the need for adjuvant chemotherapy increased in 18.8%. In luminal-A tumours, a large majority (68%) recommended endocrine treatment to postpone surgery. Postoperative radiation therapy was postponed in 20% of the cases.ConclusionsBreast cancer management was considerably modified during the COVID-19 pandemic. Our data provide a base to investigate whether these changes impact oncologic outcomes.     

Effects of locoregional radiotherapy in patients with metastatic breast cancer

ObjectivesThis study aims to assess the clinical outcomes of patients with metastatic breast cancer (MBC) who underwent local radiation therapy (RT) for the primary site.Material and methodsBetween 2005 and 2013, we retrospectively evaluated patients with MBC who received breast or chest wall RT with or without regional lymph node irradiation.Results2761 patients with breast cancer were treated with RT. Of them, 125 women with stage IV breast carcinoma were included. The median follow-up was 15 months (ranging from 3.8 to 168 months), when 54.7% of the patients had died; local progression was observed in 22.8% of the patients. The mean overall survival (OS) and local progression free survival (LoPFS) were 23.4 ± 2.4 months and 45.1 ± 2.9 months, respectively. Three- and five-year overall survival rates were, respectively, 21.2% and 13.3%. Local progression free survival was the same, 67.3%, at three and five years, respectively. Karnofsky Performance Status (KPS) (p = 0.015), number of metastatic sites (p = 0.031), RT dose (p = 0.0001) and hormone therapy (p = 0.0001) were confirmed as independent significant variables correlated with OS. The variables that were independently correlated with LoPFS were the number of previous chemotherapy lines (p = 0.038) and RT dose (p = 0.0001).ConclusionRT of the primary site in patients with MBC is well tolerated. The factors that presented positive impact on survival were good KPS, low disease burden (1–3 metastatic sites), and the use of hormone therapy.     

Triple-negative breast cancer outcomes: Does AJCC 8th staging improve chemotherapy decision-making

PurposeTo investigate the effect of the 8th American Joint Committee on Cancer (AJCC) pathological prognostic staging on chemotherapy decision-making for triple-negative breast cancer (TNBC) patients with T1-2N0M0 disease.MethodsPatients diagnosed with T1-2N0M0 TNBC were retrieved from the Surveillance, Epidemiology, and End Results program. Statistical methods including Kaplan-Meier survival curve, receiver operating characteristics curve, and Cox proportional hazard model.ResultsWe identified 12,156 patients, including 9371 (77.1%) patients who received chemotherapy. Overall, 57.4% of patients (n = 6975) were upstaged after being reassigned by the 8th AJCC staging. However, the 8th staging of AJCC did not have a greater prognostic value compared to the 7th staging (P = 0.064). The receipt of chemotherapy significantly improved the breast cancer-specific survival for stage T1c and T2 tumors (P < 0.001), but not for stage T1a (P = 0.188) and T1b (P = 0.376) tumors. Using AJCC 8th staging, chemotherapy benefit was only found in stage IIA patients (P = 0.002), but not for stage IA (P = 0.653) and IB (P = 0.492) patients. There were 9564 patients with stage T1c and T2 diseases and 4979 patients with 8th AJCC stage IIA disease. Therefore, approximately half of patients (47.9%, n = 4585) may be safe to omit chemotherapy using the AJCC 8th staging compared to the current chemotherapy recommendation for T1-2N0M0 TNBC.ConclusionThe 8th AJCC staging system did not demonstrate the superior discriminatory ability of prognostic stratification than the 7th AJCC staging system in T1-2N0M0 TNBC. However, this new AJCC staging could more accurately predict the chemotherapy benefit, thereby enabling more patients to avoid unnecessary chemotherapy.