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Most BRCA1-associated breast tumours are basal-like yet originate from luminal progenitors. BRCA1 is best known for its functions in double-strand break repair and resolution of DNA replication stress. However, it is unclear whether loss of these ubiquitously important functions fully explains the cell lineage-specific tumorigenesis. In vitro studies implicate BRCA1 in elimination of R-loops, DNA-RNA hybrid structures involved in transcription and genetic instability. Here we show that R-loops accumulate preferentially in breast luminal epithelial cells, not in basal epithelial or stromal cells, of BRCA1 mutation carriers. Furthermore, R-loops are enriched at the 5′ end of those genes with promoter-proximal RNA polymerase II (Pol II) pausing. Genetic ablation of Cobra1, which encodes a Pol II-pausing and BRCA1-binding protein, ameliorates R-loop accumulation and reduces tumorigenesis in Brca1-knockout mouse mammary epithelium. Our studies show that Pol II pausing is an important contributor to BRCA1-associated R-loop accumulation and breast cancer development., The vast majority of BRCA1-driven breast cancers derive from luminal progenitor cells but the mechanisms of this lineage specificity are unclear. Here the authors show that dangerous accumulation of DNA-RNA hybrid structures due to RNA polymerase II pausing, occurs specifically in luminal epithelial cells.

Background Acquisition of negative resection margins is paramount in the surgical management of operable breast cancer. Management of positive margins following mastectomy and immediate breast reconstruction is presently poorly defined. Objectives The present study aims at defining morbidity and cosmetic sequela of re-excision procedures aimed at clearing involved mastectomy margins in the setting of immediate autologous breast reconstruction. Oncologic outcomes are recorded. Methods A retrospective study of patients that underwent skin-sparing mastectomy followed by immediate deep inferior epigastric perforator flap breast reconstruction was performed. Patients found to have positive mastectomy margins underwent margin re-excision during a separate procedure. Method of positive margin exposure and resection is described. Flap morbidity and cosmetic outcome following margin re-excision was compared between reconstructed breasts that underwent re-excision vs those reconstructed after prophylactic mastectomy (controls). Cancer recurrence was recorded during the follow-up period. Results Thirty-six (2.5%) out of 1443 patients were found to have positive mastectomy margins following immediate breast reconstruction between May 2007 and November 2012. Location of positive margins was evenly distributed in all breast regions. Although flap morbidity was similar, a trend (P > 0.05) toward higher seroma formation and fat necrosis was reported in breasts following re-excision vs controls. With a mean follow-up period of 28 months, cosmetic outcome between breasts that underwent re-excision vs controls were similar. Cancer recurrence was reported in 3 (8.3%) patients. Conclusions Re-excision of positive mastectomy margins following immediate autologous breast reconstruction requires a multidisciplinary approach and may be performed with minimal additional morbidity while preserving optimal cosmetic outcome. Level of evidence 3.

Nature Communications 8: Article number: 15908 (2017); Published 26 June 2017; Updated 30 March 2018 The original version of this Article omitted the following from the Acknowledgements: ‘The work was also supported by a grant to Y.H. from the Cancer Prevention Research Institute of Texas CPRIT RP170126.

BACKGROUND: Fine-needle aspiration (FNA) is the most accurate and cost-effective method for evaluating thyroid nodules. However, FNA-induced secondary changes completely replacing thyroid tumors (vanishing tumors) may create a novel problem. In this study, we highlight the diagnostic and management issues associated with the unintended consequences of ultrasonography (US)-guided FNA. METHODS: Fourteen thyroid glands (11 women and 3 men, ages 33–64 years) with vanishing tumors were prospectively identified between 2009 and 2012 upon surgical resection. Cytology and histopathology slides were reviewed, and second opinions were obtained when necessary. RESULTS: The cytology of the 14 vanishing tumors was suspicious/positive for papillary thyroid carcinoma (PTC) in 5, indeterminate (atypia of unknown significance) in 5, benign in 2, follicular neoplasm in 1, and nondiagnostic in 1 nodule. Upon thyroidectomy, the vanishing tumors ranged in size from 0.4 to 3.5 cm (median 0.7 cm). Microscopically, the nodules showed cystic degeneration, organizing hemorrhage, granulation tissue, fibrosis, and microcalcifications. In seven tumors, a few residual malignant cells (PTC in five) or residual benign follicles (hemorrhagic cyst in two) at the periphery of the vanishing tumors helped with the final diagnosis. The remaining seven tumors were completely replaced by FNA-induced secondary changes, and had the cytology diagnosis of benign in one, follicular neoplasm in one, and suspicious/positive for PTC in five. Of the latter five, two showed additional separate foci of PTC, while three vanishing tumors (0.5, 1.2, and 1.6 cm) had no residual malignant cells and no additional carcinoma leading to a final diagnosis of negative for malignancy. CONCLUSIONS: US-guided FNA may lead to complete obliteration of thyroid nodules, rendering final diagnosis upon thyroidectomy difficult or impossible. In these unusual circumstances, the possibility that the surgical pathology may be nonrepresentative should be considered if the cytologic features on FNA are sufficient by themselves to support a definitive diagnosis of PTC.

Background: Patients with metastatic colorectal cancer that is limited to a few lesions in the lungs or liver may benefit from the complete surgical removal of all deposits of metastatic cancer (referred to as a curative metastasectomy). Although the outcome after this curative-intent surgery is considerably better than patients with more extensive metastatic cancer, only a third of the surgical patients are actually cured. As a result, there is a great need for a mechanism to predict outcome after surgery for limited metastatic cancer, in order to better match patients with effective therapy. Fascin is an actin bundling protein linked to epithelial to mesenchymal transformation and metastatic progression. Fascin expression has previously demonstrated prognostic potential in patients with extensive metastatic colorectal cancer. We hypothesized that Fascin expression within surgically removed colorectal cancer metastases would correlate with survival after curative-intent surgery. Methods: 82 paraffin embedded colorectal metastases collected after curative-intent surgery between 1990 and 2008 were incorporated into tissue microarrays (TMAs) in two fold redundancy. Fascin expression within the metastases was determined by quantitative immunofluorescence using Automated Quantitative Analysis (AQUA), and normalized based on a panel of cell lines (AQUA score range 0-72). The median follow up was 2.8 years and thus far 51 patients have died (62%). Results: The majority of colorectal cancer metastases had been removed from the liver (70 patients), while 12 represented pulmonary metastases. There were no differences in survival by location of metastases (p = .65). Survival was analyzed based on high (top quartile, n = 21) and low (bottom three quartiles, n = 61) expression of Fascin (AQUA score cut point of 3.4). High expression of Fascin correlated with a worse prognosis, HR 1.97; 95% CI 1.07-3.62 p = .009. Conclusions: Fascin expression within colorectal cancer metastases may be used to predict outcome after curative-intent surgery. Patients with high Fascin expression may be considered for additional therapy or may be advised against particularly high risk procedures. Further study is warranted to validate the role of Fascin expression analysis in this patient cohort. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 349. doi:10.1158/1538-7445.AM2011-349