Programmed cell death ligand 1 (PD-L1) expression is predictive for benefit from immunotherapy in several human malignancies including triple negative breast cancer. Lower positivity rates but a larger relative benefit from atezolizumab has been implied when PD-L1 status is assessed at metastatic sites. We aimed to study the discordance of PD-L1 expression between primary tumor and metastasis in breast cancer due to its potential clinical utility. Cochrane Library, Embase, Medline and Web of science were searched for studies reporting on PD-L1 expression in primary and metastatic breast cancer, followed by data extraction. Outcomes included pooled PD-L1 positivity rates in tumor cells, immune cells or both in primary tumor and metastasis, PD-L1 discordance between matched primary tumors and metastasis and direction of discordance. Of 2552 identified entries following de-duplication, 20 studies fulfilled the predefined inclusion criteria. Pooled PD-L1 positivity rate was higher in primary tumors compared to metastasis when assessed in immune cells (51.2% vs 37.1% p < 0.001) and tumor/immune cells (30.1% vs 14.6% p < 0.001), but not in tumor cells (18.7% vs 17.8% p = 0.65). PD-L1 positivity was lowest when assessed in bone metastases (12%) and highest in lymph nodes (60%). Discordance between primary tumors and metastasis was bidirectional, with higher pooled discordance rates when PD-L1 expression was assessed in immune compared to tumor cells (39.5% vs 13.6%, p < 0.001). The observed considerable discordance between PD-L1 status in primary and metastatic breast cancer emphasizes the importance of appropriate tissue sampling when selecting patients for immunotherapy.

Background. The purpose of the study was to estimate the impact on survival and fracture rates of the use of zoledronic acid versus no use (or delayed use) in the adjuvant treatment of patients with early-stage (stages I–III) breast cancer. Materials and Methods. We performed a systematic review and meta-analysis of randomized clinical trials. Trials were located through PubMed, ISI, Cochrane Library, and major cancer scientific meeting searches. All trials that randomized patients with primary breast cancer to undergo adjuvant treatment with zoledronic acid versus nonuse, placebo, or delayed use of zoledronic acid as treatment to individuals who develop osteoporosis were considered eligible. Standard meta-analytic procedures were used to analyze the study outcomes. Results. Fifteen studies were considered eligible and were further analyzed. The use of zoledronic acid resulted in a statistically significant better overall survival outcome (five studies, 6,414 patients; hazard ratio [HR], 0.81; 95% confidence interval [CI], 0.70–0.94). No significant differences were found for the disease-free survival outcome (seven studies, 7,541 patients; HR, 0.86; 95% CI, 0.70–1.06) or incidence of bone metastases (seven studies, 7,543 patients; odds ratio [OR], 0.94; 95% CI, 0.64–1.37). Treatment with zoledronic acid led to a significantly lower overall fracture rate (OR, 0.78; 95% CI, 0.63–0.96). Finally, the rate of osteonecrosis of the jaw was 0.52%. Conclusion. Zoledronic acid as adjuvant therapy in breast cancer patients appears to not only reduce the fracture risk but also offer a survival benefit over placebo or no treatment.

An increased number of women are expected to conceive after the diagnosis of early breast cancer. Most physicians recommend that pregnancy be delayed by 2 to 3 years after diagnosis of early breast cancer, but this recommendation is based on data from trials with small patient cohorts. Furthermore, a healthy mother effect (HME) selection bias may be operative in most of these studies, because women undergoing childbearing after treatment were healthier when compared with the control group. To perform a systematic review and meta-analysis of published trials corrected for HME bias so as to assess the effect of pregnancy (at least 10 months after diagnosis) versus no pregnancy on overall survival of primary breast cancer patients less than 45 years. We searched MEDLINE and Thomson Reuters (ISI) Web of Knowledge for eligible studies. From each study we extracted the relative hazard ratio or, if not provided, all the necessary data to impute it. In cases where the duration from diagnosis to pregnancy was not reported, we extracted relevant data to estimate it. Our electronic search strategy yielded 1623 hits pertaining to 20 potentially eligible studies involving 49,370 premenopausal breast cancer patients. Ten studies were eligible after considering HME potential bias in matching controls. Among these, 9 studies (pregnant 1089, matched-controls 13051) contained data appropriate for analysis. Overall survival was statistically higher among patients who became pregnant compared to controls: fixed effect model estimated pooled hazard ratio for death 0.51 (95% confidence interval: 0.42-0.62). No study heterogeneity was observed: Q = 10.4, P = 0.17; I(2) = 48%. The pooled available evidence indicates that in early breast cancer patients, pregnancy that occurs at least 10 months after diagnosis does not jeopardize prognosis and may actually confer significant survival benefit. Obstetricians & Gynecologists, Family Physicians. After completing this CME activity, physicians should be better able to assess the effect pregnancy has on long-term survival in primary breast cancer patients under age 45; counsel patients on the safety of pregnancy after breast cancer diagnosis and treatment; and interpret how pregnancy may be associated with improved breast cancer survival.

Traditionally, estrogen receptor (ER)-positive breast cancer has been defined as tumors with ≥1% positive for ER. The updated American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines recommend that tumors with ER expression of 1%-10% should be classified as ER-low-positive, recognizing the limited clinical evidence on the prognostic and predictive role of low ER expression. We aimed to investigate the predictive role of ER-low expression to neoadjuvant chemotherapy (NeoCT) and the prognostic significance of ER-low expressing breast tumors compared with ER-positive or ER-negative breast tumors. A meta-analysis was conducted using the Meta-analyses Of Observational Studies in Epidemiology (MOOSE) guidelines and eligible articles were identified on PubMed and ISI Web of Science databases. The primary outcome was pathologic complete response and secondary outcomes were disease-free survival (DFS) and overall survival (OS). Twelve retrospective cohort studies were included in the meta-analysis. NeoCT resulted in higher pathologic complete response among patients with ER-low expression compared with ER-positive and comparable to ER-negative. Patients with ER-low breast cancer had a statistically significant worse DFS and OS compared with patients with ER-positive breast cancer, whereas no difference in DFS or OS was observed between ER-low and ER-negative subgroups. The current evidence suggests that ER-low breast cancer has a more similar outcome to ER-negative than to ER-positive breast cancer in terms of DFS and OS. ER-low expression seems also to have a predictive role regarding NeoCT. Considering the certainty of current evidence categorized as low to moderate, our results urge the need for well-designed prospective studies investigating the molecular background and the most appropriate treatment strategy for ER-low expressing breast cancer.