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Background Aromatase inhibitors (AIs) are the preferred endocrine treatment for postmenopausal hormonal receptor-positive breast cancer. However, there is controversy on the long-term cardiovascular and cerebrovascular safety of AIs over that of tamoxifen. Methods We analyzed the National Health Information Database (NHID) of 281,255 women over a 20-year-old diagnosed with breast cancer between 2009 and 2016. Cardiovascular events (CVEs) were defined as the development of the following, acute coronary syndrome (ACS), ischemic and hemorrhagic stroke, defined by using insurance claim records. The model was constructed by Cox proportional hazard regression and this model was used to analyze the effects of AI and tamoxifen on CVE. Results We included 47,569 women for the final analysis. Patients were classified into ‘No hormonal treatment (n = 18,807), ‘Switch ( n = 2097)’, ‘Tamoxifen ( n = 7081)’ and ‘AI ( n = 19,584)’. There were 2147 CVEs in 2032 patients (4.1%). Univariate analysis showed that women with tamoxifen had significantly lower risk for CVEs compared to no-treatment (hazard ratio (HR) 0.84, 95% confidence interval (CI) 0.74–0.97) while AI showed no such effect (HR 0.93, 95% CI 0.84–1.02). After adjusting for other risk factors (hypertension, dyslipidemia, family history), the use of tamoxifen was associated with significant protective effect against ACS (HR 0.63, 95% CI 0.47–0.84). Conclusions Our results, based on the NHID, supports the protective effect of tamoxifen against CVE in Korean breast cancer patients aged 55 and older that is not seen with AIs. Our results can guide the selection of adjuvant hormonal treatment agents for Korean breast cancer patients based on their risk of developing CVE.

Ki67 level was higher in younger patients. However, very young patients had a poorer prognosis regardless of Ki67 level. Unknown biologic factors other than high cell proliferation might play a role in the aggressiveness of hormone receptor-positive breast cancer in very young patients.

While transfer-RNAs (tRNAs) are known to transport amino acids to ribosome, new functions are being unveiled from tRNAs and their fragments beyond protein synthesis. Here we show that phosphorylation of 90-kDa RPS6K (ribosomal proteins S6 kinase) was enhanced by tRNALeu overexpression under amino acids starvation condition. The phosphorylation of 90-kDa RPS6K was decreased by siRNA specific to tRNALeu and was independent to mTOR (mammalian target of rapamycin) signaling. Among the 90-kDa RPS6K family, RSK1 (ribosomal S6 kinase 1) and MSK2 (mitogen-and stress-activated protein kinase 2) were the major kinases phosphorylated by tRNALeu overexpression. Through SILAC (stable isotope labeling by/with amino acids in cell culture) and combined mass spectrometry analysis, we identified EBP1 (ErbB3-binding protein 1) as the tRNALeu-binding protein. We suspected that the overexpression of free tRNALeu would reinforce ErbB2/ErbB3 signaling pathway by disturbing the interaction between ErbB3 and EBP1, resulting in RSK1/MSK2 phosphorylation, improving cell proliferation and resistance to death. Analysis of samples from patients with breast cancer also indicated an association between tRNALeu overexpression and the ErbB2-positive population. Our results suggested a possible link between tRNALeu overexpression and RSK1/MSK2 activation and ErbB2/ErbB3 signaling.

Previous randomized trials, performed decades ago, showed no survival benefit of intensive screening for distant metastasis in breast cancer. However, recent improvements in targeted therapies and diagnostic accuracy of imaging have again raised the question of the clinical benefit of screening for distant metastasis. Therefore, we investigated the association between the use of modern imaging and survival of patients with breast cancer who eventually developed distant metastasis. We retrospectively reviewed data of 398 patients who developed distant metastasis after their initial curative treatment between January 2000 and December 2015. Patients in the less-intensive surveillance group (LSG) had significantly longer relapse-free survival than did patients in the intensive surveillance group (ISG) (8.7 vs. 22.8 months; p = 0.002). While the ISG showed worse overall survival than the LSG did (50.2 vs. 59.9 months; p = 0.015), the difference was insignificant after adjusting for other prognostic factors. Among the 225 asymptomatic patients whose metastases were detected on imaging, the intensity of screening did not affect overall survival. A small subgroup of patients showed poor survival outcomes when they underwent intensive screening. Patients with HR-/HER2 + tumors and patients who developed lung metastasis in the LSG had better overall survival than those in the ISG did. Highly intensive screening for distant metastasis in disease-free patients with breast cancer was not associated with significant survival benefits, despite the recent improvements in therapeutic options and diagnostic techniques.