Christine B. Teal

Breast-specific gamma imaging as an adjunct imaging modality for the diagnosis of breast cancer

PURPOSE To retrospectively determine the sensitivity and specificity of breast-specific gamma imaging (BSGI) for the detection of breast cancer by using pathologic results as the reference standard. MATERIALS AND METHODS This study was Institutional Review Board approved and Health Insurance Portability and Accountability Act compliant. Informed consent was obtained for participants who were not imaged as part of their clinical protocol but were participating in other Institutional Review Board-approved studies that used BSGI. A retrospective review of 146 women (aged 32-98 years) undergoing BSGI and breast biopsy was performed. Patients underwent BSGI with intravenous injection of 30 mCi (1110 MBq) of technetium 99 ((99m)Tc)-sestamibi and were imaged in craniocaudal and mediolateral oblique projections. Study images were assigned scores, and scores were classified as positive (focal increased radiotracer uptake) or negative (no uptake or scattered heterogeneous physiologic uptake) and compared with biopsy results. The sensitivity, specificity, and positive and negative predictive values were determined. RESULTS In 146 patients, 167 lesions underwent biopsy, of which 83 (16 ductal carcinoma in situ [DCIS] and 67 invasive cancers) were malignant. Of 84 nonmalignant lesions, 82 were benign and two showed atypical histologic results (one atypical lobular hyperplasia and one lobular carcinoma in situ). BSGI helped detect cancer in 80 of 83 malignant lesions with a sensitivity of 96.4% (95% confidence interval [CI]: 92%, 99%) and correctly identified 50 of 84 nonmalignant lesions as negative for cancer with a specificity of 59.5% (95% CI: 49%, 70%). The positive predictive value for 80 of 114 malignant lesions with a BSGI examination with findings positive for cancer was 68.8% (95% CI: 60%, 78%) and the negative predictive value for 50 of 53 nonmalignant lesions was 94.3% (95% CI: 88%, 99%). The smallest invasive cancer and DCIS detected were both 1 mm. BSGI helped detect occult cancer not visualized at mammography or ultrasonography in six patients. CONCLUSION BSIG has high sensitivity (96.4%) and moderate specificity (59.5%) helping detect breast cancers.

Breast-Specific Gamma Imaging with 99mTc-Sestamibi and Magnetic Resonance Imaging in the Diagnosis of Breast Cancer—A Comparative Study

Abstract:  The purpose of this study was to compare the sensitivity and specificity of breast‐specific gamma imaging (BSGI) using a high‐resolution breast‐specific gamma camera and magnetic resonance imaging (MRI) in patients with indeterminate breast findings. Twenty‐three women with an indeterminate breast finding that required BSGI and MRI as deemed necessary by the interpreting radiologist or referring physician were included. MRI was performed on a GE 1.5T scanner and BSGI was performed on a Dilon high‐resolution breast‐specific gamma camera. All imaging findings were correlated with pathologic diagnosis. Thirty‐three indeterminate lesions were evaluated in the study. There were a total of nine pathologically confirmed cancers. There was no statistically significant difference in sensitivity of cancer detection between BSGI and MRI. BSGI demonstrated a greater specificity than MRI, 71% and 25%, respectively. BSGI has equal sensitivity and greater specificity than MRI for the detection of breast cancer.

Role of deregulated microRNAs in breast cancer progression Using FFPE tissue

MicroRNAs (miRNAs) contribute to cancer initiation and progression by silencing the expression of their target genes, causing either mRNA molecule degradation or translational inhibition. Intraductal epithelial proliferations of the breast are histologically and clinically classified into normal, atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC). To better understand the progression of ductal breast cancer development, we attempt to identify deregulated miRNAs in this process using Formalin-Fixed, Paraffin-Embedded (FFPE) tissues from breast cancer patients. Following tissue microdissection, we obtained 8 normal, 4 ADH, 6 DCIS and 7 IDC samples, which were subject to RNA isolation and miRNA expression profiling analysis. We found that miR-21, miR-200b/c, miR-141, and miR-183 were consistently up-regulated in ADH, DCIS and IDC compared to normal, while miR-557 was uniquely down-regulated in DCIS. Interestingly, the most significant miRNA deregulations occurred during the transition from normal to ADH. However, the data did not reveal a step-wise miRNA alteration among discrete steps along tumor progression, which is in accordance with previous reports of mRNA profiling of different stages of breast cancer. Furthermore, the expression of MSH2 and SMAD7, two important molecules involving TGF-β pathway, was restored following miR-21 knockdown in both MCF-7 and Hs578T breast cancer cells. In this study, we have not only identified a number of potential candidate miRNAs for breast cancer, but also found that deregulation of miRNA expression during breast tumorigenesis might be an early event since it occurred significantly during normal to ADH transition. Consequently, we have demonstrated the feasibility of miRNA expression profiling analysis using archived FFPE tissues, typically with rich clinical information, as a means of miRNA biomarker discovery.

miR-638 mediated regulation of BRCA1 affects DNA repair and sensitivity to UV and cisplatin in triple-negative breast cancer

IntroductionTriple-negative breast cancer (TNBC) represents 15 to 20% of all types of breast cancer; however, it accounts for a large number of metastatic cases and deaths, and there is still no effective treatment. The deregulation of microRNAs (miRNAs) in breast cancer has been widely reported. We previously identified that miR-638 was one of the most deregulated miRNAs in breast cancer progression. Bioinformatics analysis revealed that miR-638 directly targets BRCA1. The aim of this study was to investigate the role of miR-638 in breast cancer prognosis and treatment.MethodsFormalin-fixed, paraffin-embedded (FFPE) breast cancer samples were microdissected into normal epithelial and invasive ductal carcinoma (IDC) cells, and total RNA was isolated. Several breast cancer cell lines were used for the functional analysis. miR-638 target genes were identified by TARGETSCAN-VERT 6.2 and miRanda. The expression of miR-638 and its target genes was analyzed by real-time qRT-PCR and Western blotting. Dual-luciferase reporter assay was employed to confirm the specificity of miR-638 target genes. The biological function of miR-638 was analyzed by MTT chemosensitivity, matrigel invasion and host cell reactivation assays.ResultsThe expression of miR-638 was decreased in IDC tissue samples compared to their adjacent normal controls. The decreased miR-638 expression was more prevalent in non-TNBC compared with TNBC cases. miR-638 expression was significantly downregulated in breast cancer cell lines compared to the immortalized MCF-10A epithelial cells. BRCA1 was predicted as one of the direct targets of miR-638, which was subsequently confirmed by dual-luciferase reporter assay. Forced expression of miR-638 resulted in a significantly reduced proliferation rate as well as decreased invasive ability in TNBC cells. Furthermore, miR-638 overexpression increased sensitivity to DNA-damaging agents, ultraviolet (UV) and cisplatin, but not to 5-fluorouracil (5-FU) and epirubicin exposure in TNBC cells. Host cell reactivation assays showed that miR-638 reduced DNA repair capability in post UV/cisplatin-exposed TNBC cells. The reduced proliferation, invasive ability, and DNA repair capabilities are associated with downregulated BRCA1 expression.ConclusionsOur findings suggest that miR-638 plays an important role in TNBC progression via BRCA1 deregulation. Therefore, miR-638 might serve as a potential prognostic biomarker and therapeutic target for breast cancer.

Methylation of the tumor suppressor protein, BRCA1, influences its transcriptional cofactor function.

Background Approximately half of hereditary breast cancers have mutations in either BRCA1 or BRCA2. BRCA1 is a multifaceted tumor suppressor protein that has implications in processes such as cell cycle, transcription, DNA damage response and chromatin remodeling. This multifunctional nature of BRCA1 is achieved by exerting its many effects through modulation of transcription. Many cellular events are dictated by covalent modification of proteins, an important mechanism in regulating protein and genome function; of which protein methylation is an important posttranslational modification with activating or repressive effects. Methods/Principal Findings Here we demonstrate for the first time that BRCA1 is methylated both in breast cancer cell lines and breast cancer tumor samples at arginine and lysine residues through immunoprecipitation and western blot analysis. Arginine methylation by PRMT1 was observed in vitro and the region of BRCA1 504–802 shown to be highly methylated. PRMT1 was detected in complex with BRCA1 504–802 through in vitro binding assays and co-immunoprecipitated with BRCA1. Inhibition of methylation resulted in decreased BRCA1 methylation and alteration of BRCA1 binding to promoters in vivo as shown through chromatin immunoprecipitation assays. Knockdown of PRMT1 also resulted in increased BRCA1 binding to particular promoters in vivo. Finally, following methylation inhibition, Sp1 was found to preferentially associate with hypo-methylated BRCA1 and STAT1 was found to preferentially associate with hyper-methylated BRCA1. Conclusions/Significance These results suggest that methylation may influence either the ability of BRCA1 to bind to specific promoters or protein-protein interactions which alters the recruitment of BRCA1 to these promoters. Thus, given the importance of BRCA1 to genomic stability, methylation of BRCA1 may ultimately affect the tumor suppressor ability of BRCA1.

Detection of occult foci of breast cancer using breast-specific gamma imaging in women with one mammographic or clinically suspicious breast lesion.

RATIONALE AND OBJECTIVES The aim of this study was to determine how often breast-specific gamma imaging (BSGI) identifies occult cancerous lesions in women with one suspicious lesion detected on mammography or physical exam. MATERIALS AND METHODS A retrospective review was performed of the records of all patients who underwent BSGI between January 1, 2004, and June 4, 2007. Included in the study were 159 women who had one suspicious breast lesion on physical exam and/or mammography and who underwent BSGI to evaluate for occult lesions in the breast. All patients had one or more foci of cancer proven pathologically. BSGI findings were classified as normal or abnormal on the basis of the presence of focal radiotracer uptake. RESULTS BSGI detected additional suspicious lesions occult to mammography and physical exam in 46 of 159 women (29%). BSGI identified occult cancer in 14 of 40 women (35%) who underwent biopsy or excision because of BSGI findings and in 14 of the 159 (9%) women in this study. In nine women, the occult cancer was present in the same breast as the index lesion (6%), and in five women, the occult cancer was found in the contralateral breast (3%). CONCLUSIONS BSGI is an effective imaging modality in the identification of mammographically and clinically occult cancer in women with one suspicious breast lesion.

Breast-specific gamma imaging for the detection of breast cancer in dense versus nondense breasts.

OBJECTIVE The purpose of this study was to evaluate the sensitivity of breast-specific gamma imaging (BSGI) for the detection of breast cancer in dense versus nondense breasts. MATERIALS AND METHODS This was a retrospective study of 341 women with biopsy-proven breast cancer diagnosed from January 2004 to August 2009 who underwent BSGI before surgical excision. Patients with predominantly fatty replaced (BI-RADS density 1) or scattered fibroglandular tissue (BI-RADS density 2) breasts were classified as nondense, and those with heterogeneously dense (BI-RADS density 3) or extremely dense tissue (BIRADS density 4) were classified as dense. BSGI examinations exhibiting focal increased radiotracer uptake in the area of biopsy-proven cancer were classified as positive according to BSGI reports in the medical record. The sensitivity of BSGI was calculated using Microsoft Excel 2003. Between-group differences were evaluated statistically using the Student t test for continuous variables and the chi-square test for categoric variables, with p < 0.05 considered statistically significant. RESULTS The overall sensitivity of BSGI for breast cancer detection was 95.4%. Positive BSGI examinations were present in 136 of 142 nondense breast cancers and 195 of 205 dense breast cancers, for sensitivities of 95.8% and 95.1%, respectively. There was no significant difference in BSGI breast cancer detection and parenchymal breast density (p = 0.459). CONCLUSION BSGI has high sensitivities for the detection of breast cancer in women with dense and nondense breasts and is an effective adjunct imaging modality in women with both dense and nondense breasts.

Mastectomy and Contralateral Prophylactic Mastectomy Rates: An Institutional Review

BackgroundBreast conservation surgery (BCS) followed by radiation is as effective as mastectomy for long-term survival and is considered standard of care for early-stage breast cancer. An increasing number of patients are opting for cancer-side mastectomies (CM) and often contralateral prophylactic mastectomies (CPM). Our study investigates if there are increasing trends in our patient population toward CM and CPM and identifies common factors associated with those electing to have more extensive surgery.MethodsA retrospective analysis was performed on 812 breast cancer surgeries between January 2001 and December 2009 at The George Washington University Breast Care Center. BCS-eligible patients who elected to have BCS were compared with those who chose CM. Patients who underwent CM were compared with patients undergoing CM and CPM.ResultsA personal or family history of breast cancer and larger tumor size were positively associated with choosing CM in BCS-eligible patients. A nonstatistically significant trend toward CM was seen in younger patients. Age, family history, fewer children, Caucasian race, and reconstructive surgery were positively associated with choosing CPM.ConclusionMastectomy rates at this institution have not shown the recent sharp increase observed by some authors. The association of age, race, family history, and parity with CPM has been corroborated in multiple studies. However, there is disagreement between statistically significant findings among investigators evaluating factors associated with CPM, and there is limited data in the literature characterizing BCS-eligible patients who chose CM. Larger prospective studies are necessary to further evaluate CM and CPM rates.

Evaluation of the Benefit of Using Blue Dye in Addition to Radioisotope for Sentinel Lymph Node Biopsy in Patients With Breast Cancer

Abstract:  The techniques for performing sentinel lymph node biopsy (SLNB) vary from institution to institution. Some advocate blue dye only, others radioisotope only, and many utilize a combination of both. The purpose of this study is to evaluate the additional benefit that blue dye provides when used in combination with a radioisotope. From October 2001 to June 2004, 102 SLNBs were attempted in 99 patients with breast cancer using a combination of blue dye and radioisotope. A lymph node was considered a sentinel lymph node (SLN) when it was stained with blue dye, had a blue lymphatic afferent, or had increased radioactivity. Ninety‐eight patients had 101 successful identifications of SLNs, for an identification rate of 99%. Twenty‐eight patients had positive SLNs. In three of those patients, although there were SLNs identified by both techniques, the positive SLNs were identified with only blue dye. Of the 102 SLNB procedures, there were two patients whose only SLN was identified by blue dye only. Although blue dye did not improve the identification rate, there was a definite benefit in improving the false‐negative rate.

miR-671-5p inhibits epithelial-to-mesenchymal transition by downregulating FOXM1 expression in breast cancer

MicroRNA (miRNA) dysfunction is associated with a variety of human diseases, including cancer. Our previous study showed that miR-671-5p was deregulated throughout breast cancer progression. Here, we report for the first time that miR-671-5p is a tumor-suppressor miRNA in breast tumorigenesis. We found that expression of miR-671-5p was decreased significantly in invasive ductal carcinoma (IDC) compared to normal in microdissected formalin-fixed, paraffin-embedded (FFPE) tissues. Forkhead Box M1 (FOXM1), an oncogenic transcription factor, was predicted as one of the direct targets of miR-671-5p, which was subsequently confirmed by luciferase assays. Forced expression of miR-671-5p in breast cancer cell lines downregulated FOXM1 expression, and attenuated the proliferation and invasion in breast cancer cell lines. Notably, overexpression of miR-671-5p resulted in a shift from epithelial-to-mesenchymal transition (EMT) to mesenchymal-to-epithelial transition (MET) phenotypes in MDA-MB-231 breast cancer cells and induced S-phase arrest. Moreover, miR-671-5p sensitized breast cancer cells to cisplatin, 5-fluorouracil (5-FU) and epirubicin exposure. Host cell reactivation (HCR) assays showed that miR-671-5p reduces DNA repair capability in post-drug exposed breast cancer cells. cDNA microarray data revealed that differentially expressed genes when miR-671-5p was transfected are associated with cell proliferation, invasion, cell cycle, and EMT. These data indicate that miR-671-5p functions as a tumor suppressor miRNA in breast cancer by directly targeting FOXM1. Hence, miR-671-5p may serve as a novel therapeutic target for breast cancer management.