The role of the addition of ovarian suppression to tamoxifen in young women with hormone-sensitive breast cancer who remain premenopausal or regain menstruation after chemotherapy (ASTRRA): study protocol for a randomized controlled trial and progress.

BACKGROUND: Ovarian function suppression (OFS) has been shown to be effective as adjuvant endocrine therapy in premenopausal women with hormone receptor-positive breast cancer. However, it is currently unclear if addition of OFS to standard tamoxifen therapy after completion of adjuvant chemotherapy results in a survival benefit. In 2008, the Korean Breast Cancer Society Study Group initiated the ASTRRA randomized phase III trial to evaluate the efficacy of OFS in addition to standard tamoxifen treatment in hormone receptor-positive breast cancer patients who remain or regain premenopausal status after chemotherapy. METHODS: Premenopausal women with estrogen receptor-positive breast cancer treated with definitive surgery were enrolled after completion of neoadjuvant or adjuvant chemotherapy. Ovarian function was assessed at the time of enrollment and every 6 months for 2 years by follicular-stimulating hormone levels and bleeding history. If ovarian function was confirmed as premenopausal status, the patient was randomized to receive 2 years of goserelin plus 5 years of tamoxifen treatment or 5 years of tamoxifen alone. The primary end point will be the comparison of the 5-year disease-free survival rates between the OFS and tamoxifen alone groups. Patient recruitment was finished on March 2014 with the inclusion of a total of 1483 patients. The interim analysis will be performed at the time of the observation of the 187th event. DISCUSSION: This study will provide evidence of the benefit of OFS plus tamoxifen compared with tamoxifen only in premenopausal patients with estrogen receptor-positive breast cancer treated with chemotherapy. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT00912548 . Registered May 31 2009. Korean Breast Cancer Society Study Group Register KBCSG005 . Registered October 26 2009.

Omission of axillary surgery in cN0, postmenopausal ER-positive/HER2-negative breast cancer patients undergoing breast-conserving treatment.

Background: Previous clinical trials have diminished the significance of lymph node (LN) metastasis and axillary surgery in breast cancer, particularly in cN0, postmenopausal estrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative patients undergoing breast-conserving treatment (BCT). We assessed the replacement of axillary surgery with preoperative imaging modalities by analyzing the proportion of high nodal burden (HNB) patients with ≥3 LN metastases in these patients. Methods: We retrospectively identified 333 cN0, postmenopausal ER-positive/HER2-negative breast cancer patients who underwent BCT in two hospitals between January 2003 and December 2017. The proportion of LN metastasis patients and the number of metastatic LN were investigated. Risk factors of LN metastasis were analyzed and recurrence-free survival (RFS) was compared. Results: Axillary surgery confirmed LN metastasis in 81 (24.3%) of the cN0 patients. The clinical tumor size (cT) and age were factors associated with LN metastasis [cT: odds ratio (OR), 2.92, 95% confidence interval (CI): 1.69-5.05, P<0.001; age: OR, 0.33, 95% CI: 0.11-0.99, P=0.048]. However, HNB patients with ≥3 LN metastases were 15 (4.5%) of all the patients. There was statistically significant difference in the incidence of HNB between patients with cT1 tumors (3.6%) and those with cT2 tumors (7.4%) (P<0.001). Conclusions: In cN0, postmenopausal ER-positive/HER2-negative patients who underwent BCT, patients with cT1 tumors had lower rate of LN metastasis, and there were fewer instances of HNB. Therefore, in these patients, omission of axillary surgery including SLNB can be carefully considered.

The Risk of Venous Thromboembolism in Korean Patients with Breast Cancer: A Single-Center Experience.

The relationship between cancer and venous thromboembolism (VTE) has long been described. The risk of VTE in Asian patients with breast cancer remains largely unknown. This study described the incidence and risk factors of VTE in Korean patients with breast cancer. Data were collected from a retrospective database of patients who underwent breast cancer surgery between 2011 and 2020 at a single institution. The Cox proportional-hazards model was used to identify factors associated with VTE occurrences. Among the 2246 patients with breast cancer, 48 (2.1%) developed VTE during a median follow-up period of 53 months. The average incidence of VTE was 459 per 100,000 person-years. Age ≥ 60 years, male sex, chronic kidney disease, reconstructive procedures, and stage II or higher were independent predictive factors for VTE. VTE was associated with poor disease-free survival (hazard ratio (HR), 6.140; 95% confidence interval (CI), 3.480-10.835), and overall survival (HR, 8.842; 95% CI 4.386-17.824). Most VTE events were manageable with anticoagulation; three (6.3%) patients died of VTE, despite intensive care. The incidence of VTE was significantly elevated in Korean patients with breast cancer. Since VTE has a negative effect on oncologic outcomes of breast cancer, clinicians should manage its risk throughout their lifetime.

Complete Surgical Excision Is Necessary following Vacuum-Assisted Biopsy for Breast Cancer.

Vacuum-assisted breast biopsy (VABB) has been replacing excisional biopsy in the treatment of benign breast lesions. Complete surgical excision is still needed for the lesions occasionally diagnosed with breast cancer after VABB. We aimed to characterize residual tumors after VABB and define a subset of patients who do not need surgical excision after VABB. From a retrospective database, we identified patients diagnosed with breast cancer after VABB guided with ultrasonography. Patients who underwent stereotactic biopsies were excluded. We reviewed clinicopathologic data and radiologic findings of the sample. We identified 48 patients with 49 lesions. After surgical excision, the residual tumors were identified in 40 (81.6%) lesions, and there was no residual tumor in nine (18.3%) patients. Imaging studies could not accurately locate residual tumors after VABB. A small tumor size on a VABB specimen was associated with no residual tumor on final pathology. However, residual tumors were identified in four (40%) of 10 lesions with a pathologic tumor size less than 0.5 cm. In conclusion, complete surgical excision remains the primary option for most of the patients diagnosed with breast cancer after VABB. Imaging surveillance without surgery should be carefully applied for selected low-risk patients.

Clinical Outcomes Following Letrozole Treatment according to Estrogen Receptor Expression in Postmenopausal Women: LETTER Study (KBCSG-006).

PURPOSE: In this trial, we investigated the efficacy and safety of adjuvant letrozole for hormone receptor (HR)-positive breast cancer. Here, we report the clinical outcome in postmenopausal women with HR-positive breast cancer treated with adjuvant letrozole according to estrogen receptor (ER) expression levels. METHODS: In this multi-institutional, open-label, observational study, postmenopausal patients with HR-positive breast cancer received adjuvant letrozole (2.5 mg/daily) for 5 years unless they experienced disease progression or unacceptable toxicity or withdrew their consent. The patients were stratified into the following 3 groups according to ER expression levels using a modified Allred score (AS): low, intermediate, and high (AS 3-4, 5-6, and 7-8, respectively). ER expression was centrally reviewed. The primary objective was the 5-year disease-free survival (DFS) rate. RESULTS: Between April 25, 2010, and February 5, 2014, 440 patients were enrolled. With a median follow-up of 62.0 months, the 5-year DFS rate in all patients was 94.2% (95% confidence interval [CI], 91.8-96.6). The 5-year DFS and recurrence-free survival (RFS) rates did not differ according to ER expression; the 5-year DFS rates were 94.3% and 94.1%in the low-to-intermediate and high expression groups, respectively (p = 0.6), and the corresponding 5-year RFS rates were 95.7% and 95.4%, respectively (p = 0.7). Furthermore, 25 patients discontinued letrozole because of drug toxicity. CONCLUSION: Treatment with adjuvant letrozole showed very favorable treatment outcomes and good tolerability among Korean postmenopausal women with ER-positive breast cancer, independent of ER expression. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01069211.

Regulation and localization of ribosomal protein S6 kinase 1 isoforms.

Ribosomal protein S6 kinase 1 (S6K1), a critical mediator of cell growth, is overexpressed in breast cancer and is associated with poor prognosis. S6K1 has two known isoforms, p85(S6K1) and p70(S6K1). p85(S6K1) is characterized by 23 additional amino acids in the N-terminus of p70(S6K1). This is thought to target p85(S6K1) to the nucleus, while p70(S6K1) is mainly cytoplasmic. We sought to determine the activation, regulation, and function of p70(S6K1) and p85(S6K1) in breast cancer. We found that most breast cancer cell lines expressed both isoforms. Mitogen-dependent pathways concordantly regulated phosphorylation on T389, S371, and T421/S424. Phosphorylation of both isoforms was inhibited by PI3K/mTOR inhibitors. Mitogen-dependent pathways concordantly regulated the phosphorylation of the two isoforms on T389, S371, and T421/S424. Both isoforms had S6 kinase activity. We also detected a p60 isoform with antibodies to the p70(S6K1) C-terminal but not the N-terminal. Further studies on S6K1 isoforms are warranted for therapeutically targeting this pathway.

RNA-binding specificity of Y-box protein 1.

Y-box protein 1 (YB-1) is a multifunctional DNA/RNA-binding protein that regulates transcription and translation. The specificity of YB-1's RNA binding and its consequences are unknown. Because expression and subcellular localization of YB-1 have been reported to be important in breast cancer, we determined the specificity and functional impact of YB-1 mRNA-binding in MCF7 breast cancer cells. We used YB-1 antibodies to immunoprecipitate YB-1 and microarray profiling to compare YB-1-bound and total poly(A) RNA. We demonstrated that YB-1 mRNA-binding was preferential. Transcript sequences significantly associated with this binding had high GC content. Selected YB-1 mRNA-binding targets were confirmed by QRT-PCR. However, downregulation of YB-1 levels by siRNA did not affect their RNA or protein expression. Thus, YB-1 has RNA-binding specificity; however, YB-1 binding does not necessarily regulate the stability or translation of its mRNA targets. Further study is needed to determine the functional consequences of selective YB-1 mRNA binding.

eIF4E knockdown decreases breast cancer cell growth without activating Akt signaling.

Activation of translation initiation is essential for the malignant phenotype and is emerging as a potential therapeutic target. Translation is regulated by the expression of translation initiation factor 4E (eIF4E) as well as the interaction of eIF4E with eIF4E-binding proteins (e.g., 4E-BP1). Rapamycin inhibits translation initiation by decreasing the phosphorylation of 4E-BP1, increasing eIF4E/4E-BP1 interaction. However, rapamycin also inhibits S6K phosphorylation, leading to feedback loop activation of Akt. We hypothesized that targeting eIF4E directly would inhibit breast cancer cell growth without activating Akt. We showed that eIF4E is ubiquitously expressed in breast cancer cell lines. eIF4E knockdown by small interfering RNA inhibited growth in different breast cancer cell subtypes including triple-negative (estrogen receptor/progesterone receptor/HER-2-negative) cancer cells. eIF4E knockdown inhibited the growth of cells with varying total and phosphorylated 4E-BP1 levels and inhibited rapamycin-insensitive as well as rapamycin-sensitive cell lines. eIF4E knockdown led to a decrease in expression of cyclin D1, Bcl-2, and Bcl-xL. eIF4E knockdown did not lead to Akt phosphorylation but did decrease 4E-BP1 expression. We conclude that eIF4E is a promising target for breast cancer therapy. eIF4E-targeted therapy may be efficacious in a variety of breast cancer subtypes including triple-negative tumors for which currently there are no targeted therapies. Unlike rapamycin and its analogues, eIF4E knockdown is not associated with Akt activation.