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

Breast-conserving surgery is not associated with increased local recurrence in patients with early-stage node-negative triple-negative breast cancer treated with neoadjuvant chemotherapy

BACKGROUND

Neoadjuvant chemotherapy (NACT) is routinely used for patients with triple-negative breast cancer (TNBC). Upfront breast-conserving therapy (BCT) consisting of breast-conserving surgery (BCS) and adjuvant radiotherapy (RT) has been shown to be associated with improved outcome in patients with early TNBC as compared to mastectomy.

METHODS

We identified 2632 patients with early TNBC from the German Breast Group meta-database. Patients with cT1-2 cN0 and ypN0, available surgery and follow-up data were enrolled. Data of 1074 patients from 8 prospective NACT trials were available. Endpoints of interest were locoregional recurrence as first site of relapse (LRR), disease-free survival (DFS) and overall survival (OS). We performed univariate and multivariate Fine-Gray analysis and Cox regression models.

RESULTS

After a median follow-up of 64 months, there were 94 (8.8%) locoregional events as first site of relapse. Absence of pathologic complete response (pCR) was associated with increased LRR upon uni- and multivariate analysis (hazard ratio [HR] = 2.28; p < 0.001 and HR = 2.22; p = 0.001). Type of surgery was not associated with LRR. Patients in the BCS-group had better DFS and OS (DFS: HR = 0.47; p < 0.001 and OS: HR = 0.40; p < 0.001). BCS was associated with improved DFS and OS upon multivariate analysis (DFS: HR = 0.51; p < 0.001; and OS HR = 0.43; p < 0.001), whereas absence of pCR was associated with worse DFS and OS (DFS: HR = 2.43; p < 0.001; and OS: HR = 3.15; p < 0.001).

CONCLUSIONS

In this retrospective analysis of patients with early stage node-negative TNBC treated with NACT, BCS was not associated with an increased risk of LRR but with superior DFS and OS.

CircNCOR1 regulates breast cancer radiotherapy efficacy by regulating CDK2 via hsa-miR-638 binding

BACKGROUND

Despite aggressive local and regional therapy, triple-negative breast cancer (TNBC) is characterized by an increased risk of locoregional recurrence. RNA-sequencing data has identified a large number of circRNAs in primary breast cancers, but the role of specific circRNAs in regulating the radiosensitivity of TNBC is not fully understood. This research aimed to investigate the function of circNCOR1 in the radiosensitivity of TNBC.

METHODS

CircRNA high-throughput sequencing was conducted on two breast cancer MDA-MB-231 and BT549 cell lines after 6 Gy radiation. The relationship between circNCOR1, hsa-miR-638, and CDK2 was determined by RNA immunoprecipitation (RIP), FISH and luciferase assays. The proliferation and apoptosis of breast cancer cells were measured by CCK8, flow cytometry, colony formation assays, and western blot.

RESULTS

Differential expression of circRNAs was closely related to the proliferation of breast cancer cells after irradiation. Overexpression of circNCOR1 facilitated the proliferation of MDA-MB-231 and BT549 cells and impaired the radiosensitivity of breast cancer cells. Additionally, circNCOR1 acted as a sponge for hsa-miR-638 to regulate the downstream target protein CDK2. Overexpression of hsa-miR-638 promoted apoptosis of breast cancer cells, while overexpression of CDK2 alleviated apoptosis and increased proliferation and clonogenicity. In vivo, overexpression of circNCOR1 partially reversed radiation-induced loosening of tumor structures and enhanced tumor cell proliferation.

CONCLUSION

Our results demonstrated that circNCOR1 bounds to hsa-miR-638 and targets CDK2, thereby regulating the radiosensitivity of TNBC.

Is breast conservation superior to mastectomy in early stage triple negative breast cancer?

Purpose

Compare overall survival (OS) and breast cancer-specific survival (BCSS) outcomes of breast conservative therapy (BCT) and mastectomy in a large cohort of patients with early-stage triple negative breast cancer (TNBC), using a propensity score-based matching approach.

Methods

Surveillance, Epidemiology, and End Results (SEER) database was used to study the role of RT in early stage TNBC. Primary end points were OS and BCSS. Cox proportional hazard regression models and Kaplan-Meier plots were used to generate the desired outcomes. Propensity score matching was done to minimize bias.

Results

12,761 patients with T1-2N0M0 TNBC as their first malignancy were retrieved. Of these 7237 had lumpectomy with RT, and 5524 had mastectomy only. Age, race, marital status, tumor laterality, grade and stage, and receipt of chemotherapy were prognostic variables for OS and BCSS. Among 4848 matched subjects, the 5-year OS was significantly higher in patients with lumpectomy and RT (89%) compared to mastectomy alone (84.5%) (p-value <0.001). Similarly, BCSS was significantly higher in patients with lumpectomy and RT (93%) compared to mastectomy alone (91%) (p-value <0.001). On subgroup analysis, patients who are younger than 40 had similar survival outcomes after either mastectomy alone or lumpectomy with RT. However, those who are older than 60, have any grade or T stage had better survival outcomes with lumpectomy and RT.

Conclusions

Overall, lumpectomy followed by RT is associated with better OS and BCSS compared to mastectomy in T1-2N0M0 TNBC patients. Further research is needed to determine the optimal treatment strategy for specific patient subgroups.

•

BCT is associated with better OS compared to mastectomy in early-stage TNBC.

•

BCT is associated with better BCSS compared to mastectomy in early-stage TNBC.

•

Age, race, marital status, and grade/stage are prognostic for early-stage TNBC.

Outcomes after breast-conserving surgery or mastectomy in patients with triple-negative breast cancer: meta-analysis

BACKGROUND

In patients with triple-negative breast cancer (TNBC), oncological and survival outcomes based on locoregional treatment are poorly understood. In particular, the safety of breast-conserving surgery (BCS) for TNBC has been questioned.

METHODS

A meta-analysis was performed to evaluate locoregional recurrence (LRR), distant metastasis (DM), and overall survival (OS) rates in patients with TNBC who had breast-conserving surgery versus mastectomy. Estimates were pooled in random-effects analysis. The effect of study-level co-variables was assessed by univariable metaregression.

RESULTS

Fourteen studies, including 19 819 patients operated for TNBC met the inclusion criteria; 9828 patients (49.6 per cent) underwent BCS and 9991 (50.4 per cent) had a mastectomy. Patients with smaller tumours were more likely to be selected for BCS (pooled odds ratio (OR) for T1 tumours 1.95, 95 per cent c.i. 1.64 to 2.32; P < 0.001). The pooled OR for LRR was 0.64 (0.48 to 0.85; P = 0.002), indicating a statistically significantly lower odds of LRR among women who had BCS relative to mastectomy. The pooled OR for DM was 0.70 (0.53 to 0.94; P = 0.02), indicating a lower odds of DM among women who had BCS; however, this difference diminished with increasing study-level age and follow-up time. A pooled hazard ratio of 0.78 (0.69 to 0.89; P < 0.001) showed a significantly lower hazard for all-cause mortality among women undergoing BCS versus mastectomy.

CONCLUSION

These results should be interpreted cautiously owing to likely differences in selection for BCS or mastectomy in the included studies. Patients with TNBC selected for BCS do not, however, have a worse prognosis than those treated with mastectomy, and breast conservation can be offered when feasible clinically.

The effect of postmastectomy radiotherapy in node-positive triple-negative breast cancer

Background

The value of postmastectomy radiotherapy (PMRT) for pathological node-positive triple-negative breast cancers (TNBC) remains debatable. The aim of this population-based retrospective study was to evaluate the effect of PMRT on survival outcomes in this population.

Methods

Patients diagnosed with stage T1-4N1-N3M0 TNBC between 2010 and 2014 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. We used univariate and multivariate Cox regression hazards method to determine the independent prognostic factors associated with 3-year breast cancer-specific survival (BCSS). The effect of PMRT on 3-year BCSS was analyzed after stratification by pathological staging of groups.

Results

Of the 4398 patients included in this study, 2649 (60.2%) received PMRT. Younger age, black ethnicity, and advanced tumor (T) and nodal (N) stage were the independent predictors associated with PMRT receipt (all P < 0.05). Patients who received PMRT showed better 3-year BCSS (OR = 0.720, 95% CI = 0.642–0.808, P < 0.001) than those that did not. The effect of PMRT on 3-year BCSS was analyzed after stratification by pathological staging of groups. The results showed that PMRT was associated with better 3-year BCSS in patients with stage T3–4N1 (P = 0.042), T1-4N2 (P < 0.001), and T1-4N3 (P < 0.001), while comparable 3-year BCSS was found between the PMRT and non-PMRT cohorts with T1–2N1 disease (P = 0.191).

Conclusions

Radiotherapy achieved better 3-year BCSS in TNBC patients with stage T3–4N1 and T1-4N2–3 disease. However, no survival benefit was found with the addition of PMRT in patients with T1–2N1 TNBC.

Targeting PI3K and AMPKα Signaling Alone or in Combination to Enhance Radiosensitivity of Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype and is characterized by poor survival. Radiotherapy plays an important role in treating TNBC. The purpose of this study was to determine whether inhibiting the AMP-activated protein kinase (AMPK) and phosphatidylinositol 3-kinase (PI3K) pathways alone or in combination potentiates radiotherapy in TNBC. AMPKα1 and AMPKα2 knockdown diminished cyclin D1 expression and induced G1 cell cycle arrest but did not induce apoptosis alone or in combination with radiotherapy. Next, we analyzed the role of PI3K p85α, p85β, p110α, p110β, Akt1, and Akt2 proteins on TNBC cell cycle progression and apoptosis induction. Akt1 and p110α knockdown diminished cyclin D1 expression and induced apoptosis. Silencing Akt1 promoted synergistic apoptosis induction during radiotherapy and further reduced survival after radiation. Treatment with the Akt inhibitor, MK-2206 48 h after radiotherapy decreased Akt1 levels and potentiated radiation-induced apoptosis. Together, our results demonstrate that AMPKα, p110α, and Akt1 promote TNBC proliferation and that Akt1 is a key regulator of radiosensitivity in TNBC. Importantly, combining radiotherapy with the pharmacological inhibition of Akt1 expression is a potentially promising approach for the treatment of TNBC.

Downregulation of TMPRSS4 Enhances Triple-Negative Breast Cancer Cell Radiosensitivity Through Cell Cycle and Cell Apoptosis Process Impairment

Background:

Radioresistance remains a challenge for cancer radiotherapy. The present study aims to investigate the role of TMPRSS4 in triple negative breast cancer (TNBC) cell radiosensitivity.

Materials and Methods:

After transfection of MDA-MD-468 triple negative breast cancer cells line by using the lentivirus vector, the effect of TMPRSS4 down-regulation on TNBC radiosensitivity was evaluated by using cloning assay and CCK-8 assay. The CCK-8 assay was also used for performing cell proliferation analysis. Western blot was carried out to detect the expression of certain proteins related to cell cycle pathways (cyclin D1), cell apoptosis pathways (Bax, Bcl2, and Caspase3), DNA damage and DNA damage repair (TRF2, Ku80 , ˠH2AX) . The cell cycle and cell apoptosis were also investigated using flow cytometer analysis.

Results:

TMPRSS4 expression was down-regulated in MDA-MB-468 cells which enhanced MDA-MB-468 cells radiosensitivity. TMPRSS4 silencing also improved IR induced cell proliferation ability reduction and promoted cell arrested at G2/M phase mediated by 6 Gy IR associated with cyclin D1 expression inhibition. Moreover, TMPRSS4 inhibition enhanced TNBC apoptosis induced by 6 Gy IR following by over-expression of (Bax, Caspase3) and down-regulation of Bcl2 as the pro-apoptotic and anti-apoptotic proteins, respectively. Otherwise, TMPRSS4 down-regulation increases DNA damage induced by 6 Gy IR and delays DNA damage repair respectively illustrated by downregulation of TRF2 and permanent increase of Ku80 and ˠH2AX expression at 1 h and 10 h post-IR.

Conclusion:

Down-regulation of TMPRSS4 increases triple negative breast cancer cell radiosensitivity and the use of TMPRSS4 inhibitor can be encouraged for improving radiotherapy effectiveness in TNBC radioresistant patients.

T1-2N0M0 Triple-Negative Breast Cancer Treated With Breast-Conserving Therapy Has Better Survival Compared to Mastectomy: A SEER Population-Based Retrospective Analysis

BACKGROUND

For early-stage breast cancer, the two current mainstay treatments are breast-conserving therapy (BCT; lumpectomy followed by radiotherapy [RT] and BCT) and mastectomy. Generally, triple-negative breast cancer (TNBC) is more aggressive compared to hormone receptor-positive breast cancer. We sought to investigate the effect of BCT compared to mastectomy on overall survival (OS) and breast cancer-specific survival (BCSS) in T1-2N0M0 TNBC.

PATIENTS AND METHODS

A population-based retrospective analysis was performed using the Surveillance, Epidemiology, and End Results (SEER) database. Patients included in the analysis were divided into 3 groups according to surgical modality and RT: BCT, mastectomy alone, and mastectomy with RT. The survival end points were OS and BCSS, and survival analysis was performed by the Kaplan-Meier method and the log-rank test among treatment types.

RESULTS

A total of 14,910 female subjects with T1-2N0M0 TNBC diagnosed between 2010 and 2014 were included. A total of 7381 patients had BCT; 6967 had mastectomy alone, and 562 had mastectomy with RT. Patients treated with BCT had better OS (log-rank P < .05) and BCSS (log-rank P < .05) than those receiving mastectomy with or without RT. The 5-year OS was 88.6% for BCT, 83.0% for mastectomy alone, and 79.6% for mastectomy with RT. The 5-year BCSS was 94.3% for BCT, 93.3% for mastectomy alone, and 83.7% for mastectomy with RT.

CONCLUSION

In patients with T1-2N0M0 TNBC, BCT was associated with superior OS and BCSS compared to mastectomy with or without RT. After mastectomy, there was no evidence of survival benefit of RT.

Evaluation of the benefit of post-mastectomy radiotherapy in patients with early-stage breast cancer: A propensity score matching study

The present study aimed to evaluate the significance of post-mastectomy radiotherapy (PMRT) in patients with early stage (T1-2) breast cancer. The Surveillance, Epidemiology, and End Results database was searched, and data on female patients with early stage (T1-2) breast cancer with 1–3 positive axillary lymph nodes (LNs) were extracted. Patients were subdivided into two groups: Those who had received PMRT and those who had not (no PMRT). Data from the two groups were analyzed in order to identify associations between PMRT status, breast cancer-specific survival (BCSS) probability and overall survival (OS) probability using multivariate Cox proportional hazards regression and propensity score matching models. A total of 7,316 patients were included in the analysis. Prior to propensity score matching, outcome probabilities were increased in the PMRT group, compared with the no PMRT group (BCSS probabilities: 92.0 vs. 90.1%, respectively, P=0.015; OS probabilities: 89.8 vs. 86.0%, respectively, P<0.001). In multivariate analyses, tumor location was not identified as being a risk factor for BCSS (hazard ratio, 0.917; 95% confidence interval, 0.772–1.090; P=0.326). Following propensity score matching, differences between the two treatment groups (PMRT and no PMRT) in terms of their BCSS scores remained significant (93.7 vs. 90.1%, respectively; P=0.007). Compared with the no PMRT group, the OS probabilities of the PMRT group were increased (89.4 vs. 86.0%; P=0.025). In conclusion, the present results indicated that PMRT may benefit the prognosis of patients with breast cancer with early stage disease (T1-2), and those with one to three positive axillary LNs.

Silencing of XRCC4 increases radiosensitivity of triple-negative breast cancer cells

Background: Radiotherapy is an important locoregional treatment, and its effect on triple-negative breast cancer (TNBC) needs to be enhanced. The aim of the present study was to investigate the potential effects of XRCC4 on radiosensitivity of TNBC. Methods: The RNAi technique was implemented to establish the TNBC stable cell line with XRCC4 knockdown. MTT assay was used to detect the effect of XRCC4 knockdown on cell proliferation. Western blot and immunohistochemistry assays were employed to identify protein expression. Colony assay was performed to detect the effect of XRCC4 knockdown on the colony formation ability of TNBC cells with radiation treatment. Comet assay was conducted to evaluate the influence of XRCC4 silencing on DNA repair activity in ionizing radiation. In addition, we performed a survival analysis based on data in TCGA database. Results: XRCC4 knockdown by lentivirus-mediated shRNA had no significant effect on proliferation of TNBC cells. Knockdown of XRCC4 could substantially increase the sensitivity of TNBC cells to ionizing radiation. The DNA damage level was detected to be increased in the XRCC4 knockdown group, indicating there was a significant repair delay in the XRCC4-deleted cells. Clinical sample analysis exhibited that there were various XRCC4 expression in different patients with TNBC. Moreover, survival analysis showed that high expression of XRCC4 was significantly associated with poor progression-free survival after radiotherapy in TNBC patients. Conclusion: Our findings suggest that XRCC4 knockdown sensitizes TNBC cells to ionizing radiation, and could be considered as a novel predictor of radiosensitivity and a promising target for TNBC.

Breast Conservation Therapy Versus Mastectomy in Patients with T1-2N1 Triple-Negative Breast Cancer: Pooled Analysis of KROG 14-18 and 14-23

Purpose

The aim of this study is to compare the treatment outcomes of breast conserving surgery (BCS) plus radiotherapy (RT) versus mastectomy for patients with pT1-2N1 triple-negative breast cancer (TNBC).

Materials and Methods

Using two multicenter retrospective studies on breast cancer, a pooled analysis was performed among 320 patients with pT1-2N1 TNBC. All patients who underwent BCS (n=212) receivedwhole breast RTwith orwithoutregional nodal RT,while nonewho underwent mastectomy (n=108)received it. All patients received taxane-based adjuvant chemotherapy. The median follow-up periods were 65 months in the BCS+RT group, and 74 months in the mastectomy group.

Results

The median age of all patients was 48 years (range, 24 to 70 years). Mastectomy group had more patients with multiple tumors (p < 0.001), no lymphovascular invasion (p=0.001), higher number of involved lymph node (p=0.028), and higher nodal ratio ≥ 0.2 (p=0.037). Other characteristics were not significantly different between the two groups. The 5-year locoregionalrecurrence-free, disease-free, and overall survivalrates of BCS+RT group versus mastectomy group were 94.6% versus 87.7%, 89.5% versus 80.4%, and 95.0% versus 87.8%, respectively, and the differences were statistically significant after adjusting for covariates (p=0.010, p=0.006, and p=0.005, respectively).

Conclusion

In pT1-2N1 TNBC, breast conservation therapy achieved better locoregional recurrencefree, disease-free, and overall survival rates compared with mastectomy.