We previously observed that the HERV type K (HERV-K) envelope (env) protein was expressed in the majority of human breast tumors from a U.S. cohort of women from Texas. We also made the preliminary observation that the expression of HERV-K env transcripts was associated with markers of disease progression. In this follow-up study, env protein expression was evaluated immunohistochemically in an additional 195 paraffin-embedded breast tumors from a second U.S. patient cohort (Baltimore, Maryland) and in 110 tumors from Chinese patients. Moreover, we compared env transcript expression between fresh-frozen normal and cancerous breast tissues. We observed that while env mRNA and protein expression was undetectable in normal breast tissue and in a subset of uninvolved normal-appearing tissue adjacent to the tumor epithelium, it was overexpressed in most tumors. Furthermore, env expression was associated with breast cancer progression. In Baltimore cohort women, HERV-K tumor positivity was significantly associated with disease stage and lymph node metastasis. In Chinese women, HERV-K env positivity was significantly associated with tumor size, TNM stage, and lymph node metastases, which is consistent with the observations in the U.S. cohort. We also found that Chinese breast cancer patients with a high expression of HERV-K had a decreased overall survival compared with patients who had either a moderate or low HERV-K expression in their tumors (P = 0.049, χ(2) log rank test). In conclusion, the HERV-K env gene is expressed in the majority of breast cancers from U.S. or Chinese women but not in normal breast tissue. High expression of HERV-K env protein in breast cancer patients is associated with markers of disease progression and poor disease outcome, indicating that HERV-K env protein is a novel candidate prognostic marker for breast cancer.

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BackgroundThe efficacy of prophylactic cranial irradiation (PCI) in treating patients with small cell lung cancer (SCLC) has not been clear, and recent randomized studies have demonstrated conflicting results from previously published findings. The purpose of this study was to reevaluate the efficacy of PCI in patients with SCLC and to assess factors associated with its efficacy.MethodsWe conducted a quantitative meta-analysis to explore the efficacy of PCI in patients with SCLC. A literature search was performed using EMBASE, MEDLINE, Cochrane and ClinicalTrials.gov databases. We pooled the data and compared overall survival (OS) and brain metastasis (BM) between patients treated with PCI (PCI group) and patients without PCI treatment (observation group).ResultsOf the 1074 studies identified in our analysis, we selected seven studies including 2114 patients for the current meta-analysis. Our results showed that the PCI group showed decreased BM (HR = 0.45, 95% CI: 0.38–0.55, P < 0.001) and prolonged OS (HR = 0.81, 95% CI: 0.67–0.99, P < 0.001). However, in terms of OS, the pooled analysis showed a high heterogeneity (I2 = 74.1%, P = 0.001). In subgroup analyses of OS, we found that the heterogeneity mainly came from patients with brain imaging after initial chemoradiotherapy (HR = 0.94, 95% CI: 0.74–1.18, P = 0.59).ConclusionsThe results of this study showed that PCI has a significant effect on decreasing BM but little benefit in prolonging OS when brain imaging was introduced to confirm lack of BM after initial chemoradiotherapy and before irradiation.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-5251-3) contains supplementary material, which is available to authorized users.

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