Aye Aye Thike

Triple-negative breast cancer: clinicopathological characteristics and relationship with basal-like breast cancer.

Triple-negative breast cancer, defined as that with negative expression of estrogen and progesterone receptors and cerbB2, accounted for 11% of invasive breast cancers in our study, drawn from an original cohort of 7048 women diagnosed with breast cancer from the files of the Department of Pathology, Singapore General Hospital, over 14 years. Women with triple-negative breast cancer were generally postmenopausal, with adverse pathological characteristics of high histological grade and frequent nodal metastases. Using a set of 61 invasive breast cancers earlier profiled into molecular subtypes with expression arrays, we defined specificity and sensitivity values for different immunohistochemical panels of basal keratins (CK5/6, CK14, CK17, 34βE12), CD117, EGFR, p63 and SMA in defining basal-like breast cancer. Subsequent application of a tri-panel of CK14, EGFR and 34βE12 (specificity 100% and sensitivity 78%) to our group of 653 triple-negative breast cancers delineated 84% to be basal-like. Immunohistochemical expression of individual biological markers correlated with unfavorable pathological parameters. We conclude that triple-negative breast cancers in an Asian population harbor adverse pathobiological features, and an immunohistochemical surrogate panel can be reliably used to define basal-like cancers among them.

Identification of Circulating MicroRNA Signatures for Breast Cancer Detection

Purpose: There is a quest for novel noninvasive diagnostic markers for the detection of breast cancer. The goal of this study is to identify circulating microRNA (miRNA) signatures using a cohort of Asian Chinese patients with breast cancer, and to compare miRNA profiles between tumor and serum samples. Experimental Design: miRNA from paired breast cancer tumors, normal tissue, and serum samples derived from 32 patients were comprehensively profiled using microarrays or locked nucleic acid real-time PCR panels. Serum samples from healthy individuals (n = 22) were also used as normal controls. Significant serum miRNAs, identified by logistic regression, were validated in an independent set of serum samples from patients (n = 132) and healthy controls (n = 101). Results: The 20 most significant miRNAs differentially expressed in breast cancer tumors included miRNA (miR)-21, miR-10b, and miR-145, previously shown to be dysregulated in breast cancer. Only 7 miRNAs were overexpressed in both tumors and serum, suggesting that miRNAs may be released into the serum selectively. Interestingly, 16 of the 20 most significant miRNAs differentially expressed in serum samples were novel. MiR-1, miR-92a, miR-133a, and miR-133b were identified as the most important diagnostic markers, and were successfully validated; receiver operating characteristic curves derived from combinations of these miRNAs exhibited areas under the curves of 0.90 to 0.91. Conclusion: The clinical use of miRNA signatures as a noninvasive diagnostic strategy is promising, but should be further validated for different subtypes of breast cancers. Clin Cancer Res; 19(16); 4477–87. ©2013 AACR.

Predicting clinical behaviour of breast phyllodes tumours: a nomogram based on histological criteria and surgical margins

Aim To define a predictive model for clinical behaviour of breast phyllodes tumours (PT) using histological parameters and surgical margin status. Methods Cases of breast PT diagnosed in the Department of Pathology Singapore General Hospital between January 1992 and December 2010 were stratified into benign, borderline and malignant grades based on a combination of histological parameters (stromal atypia, hypercellularity, mitoses, overgrowth and nature of tumour borders). Surgical margin status was assessed. Clinical follow-up and biostatistical modelling were accomplished. Results Of 605 PT, 440 (72.7%) were benign, 111 (18.4%) borderline and 54 (8.9%) malignant. Recurrences, which were predominantly local, were documented in 80 (13.2%) women. Deaths from PT occurred in 12 (2%) women. Multivariate analysis revealed stromal atypia, overgrowth and surgical margins to be independently predictive of clinical behaviour, with mitoses achieving near significance. Stromal hypercellularity and tumour borders were not independently useful. A nomogram developed based on atypia, mitoses, overgrowth and surgical margins (AMOS criteria) could predict recurrence-free survival at 1, 3, 5 and 10 years. This nomogram was superior to a total histological score derived from adding values assigned to each of five histological parameters. Conclusion A predictive nomogram based on three histological criteria and surgical margin status can be used to calculate recurrence-free survival of an individual woman diagnosed with PT. This can be applied for patient counselling and clinical management.

Exome sequencing identifies highly recurrent MED12 somatic mutations in breast fibroadenoma

Fibroadenomas are the most common breast tumors in women under 30 (refs. 1,2). Exome sequencing of eight fibroadenomas with matching whole-blood samples revealed recurrent somatic mutations solely in MED12, which encodes a Mediator complex subunit. Targeted sequencing of an additional 90 fibroadenomas confirmed highly frequent MED12 exon 2 mutations (58/98, 59%) that are probably somatic, with 71% of mutations occurring in codon 44. Using laser capture microdissection, we show that MED12 fibroadenoma mutations are present in stromal but not epithelial mammary cells. Expression profiling of MED12-mutated and wild-type fibroadenomas revealed that MED12 mutations are associated with dysregulated estrogen signaling and extracellular matrix organization. The fibroadenoma MED12 mutation spectrum is nearly identical to that of previously reported MED12 lesions in uterine leiomyoma but not those of other tumors. Benign tumors of the breast and uterus, both of which are key target tissues of estrogen, may thus share a common genetic basis underpinned by highly frequent and specific MED12 mutations.

Hormone Receptor and c-ERBB2 Status in Distant Metastatic and Locally Recurrent Breast Cancer Pathologic Correlations and Clinical Significance

Estrogen receptor (ER), progesterone receptor (PR), and c-ERBB2 (HER2/neu) are therapeutically and prognostically important markers in the management of breast carcinoma. They are not always analyzed in distant metastatic and locally recurrent breast cancers. We compared immunohistochemical expression in a series of primary breast carcinomas with their distant metastases (n = 72) and local recurrences (n = 45) and analyzed the impact of any changes on survival. Discordance rates between primary and metastatic and between primary and locally recurrent lesions, respectively, were 18% (13/72) and 13% (6/45) for ER, 42% (30/72) and 33% (15/45) for PR, and 7% (5/72) and 2% (1/45) for c-ERBB2. There was statistically significant discordance between primary and metastatic PR status (P = .017; kappa = 0.201). Among locally recurrent tumors, 15 (33%) of 45 revealed discordance for PR (P = .006; kappa = 0.366). We observed a trend for shorter survival among women with ER- metastatic and locally recurrent tumors regardless of the primary tumor ER status. Our findings suggest a benefit for routine evaluation of ER, PR, and c-ERBB2 status in distant metastatic and locally recurrent breast cancer for therapeutic and prognostic purposes.

Loss of androgen receptor expression predicts early recurrence in triple-negative and basal-like breast cancer.

Treatment of triple-negative invasive breast cancers, defined by the absence of estrogen and progesterone receptors and c-erbB2 expression, remains challenging. Androgen receptor, a member of the nuclear receptor superfamily that is involved in signaling pathways regulating cell proliferation, has been implicated in breast tumorigenesis. We immunohistochemically examined the expression of androgen receptor, basal markers (CK14, 34βE12) and EGFR in 699 triple-negative invasive breast cancers in tissue microarrays using the streptavidin–biotin method, and correlated the findings with clinical outcome. Positive androgen receptor expression was defined as staining of 1% or more of tumor cell nuclei. Survival outcomes were estimated with the Kaplan–Meier method and compared between groups with log-rank statistics. Cox proportional hazards models were used to determine the effect of androgen receptor on survival outcomes. Immunohistochemical positivity was observed in 38% of tumors, with the proportion of stained tumor cells ranging from 1 to 95% (mean 29%, median 10%). Androgen receptor expression was inversely associated with histologic grade and mitotic score. CK14, 34βE12 and EGFR confirmed 85% of cases to be basal-like, without significant association of basal-like phenotype with androgen receptor expression. Disease-free survival was significantly better in androgen receptor-positive triple-negative breast cancer, with a trend for improved overall survival. Decreased recurrence likelihood in both triple-negative and basal-like tumors (hazard ratio, 0.704; 95% confidence intervals, 0.498–0.994; P=0.0464; and hazard ratio, 0.675; 95% confidence intervals, 0.468–0.974; P=0.0355, respectively) was noted within 5 years of diagnosis but not thereafter. Our study suggests that loss of androgen receptor in triple-negative breast cancers augurs a worse prognosis, including those with basal-like features. More work in elucidating its relationship with mechanisms of progression, as well as trials of targeted treatment for androgen receptor-expressing triple-negative tumors, needs to be performed.

Genomic landscapes of breast fibroepithelial tumors

Breast fibroepithelial tumors comprise a heterogeneous spectrum of pathological entities, from benign fibroadenomas to malignant phyllodes tumors. Although MED12 mutations have been frequently found in fibroadenomas and phyllodes tumors, the landscapes of genetic alterations across the fibroepithelial tumor spectrum remain unclear. Here, by performing exome sequencing of 22 phyllodes tumors followed by targeted sequencing of 100 breast fibroepithelial tumors, we observed three distinct somatic mutation patterns. First, we frequently observed MED12 and RARA mutations in both fibroadenomas and phyllodes tumors, emphasizing the importance of these mutations in fibroepithelial tumorigenesis. Second, phyllodes tumors exhibited mutations in FLNA, SETD2 and KMT2D, suggesting a role in driving phyllodes tumor development. Third, borderline and malignant phyllodes tumors harbored additional mutations in cancer-associated genes. RARA mutations exhibited clustering in the portion of the gene encoding the ligand-binding domain, functionally suppressed RARA-mediated transcriptional activation and enhanced RARA interactions with transcriptional co-repressors. This study provides insights into the molecular pathogenesis of breast fibroepithelial tumors, with potential clinical implications.

Triple Negative Breast Cancer: Outcome Correlation With Immunohistochemical Detection of Basal Markers

We earlier evaluated the relationship of 653 triple negative breast cancers (TNBC) with basal immunophenotypic expression by using antibodies to basal cytokeratins (CK5/6, CK14, CK17, 34βE12), p63, smooth muscle actin (SMA), epidermal growth factor receptor, and CD117, and found that a triple panel of CK14, 34βE12 and epidermal growth factor receptor determined 84% of our cases to be basal-like. Women with basal-like TNBC tended to be younger (P=0.04), have histologically higher-grade tumors (P=0.047), with positive nodal status (P=0.047), than those whose tumors were nonbasal-like. Using univariate Cox regression analysis, tumor size (P=0.003), histologic grade (P=0.006), and nodal status (P=0.017) were significant factors for disease-free survival (DFS) among TNBC, whereas age (P=0.004), tumor size (P=0.001), histologic grade (P<0.001), nodal status (P=0.011), lymphovascular invasion (P=0.032), and pushing borders (P=0.042) were important for overall survival (OS). On multivariate analysis, age was statistically significant for both DFS and OS (P=0.033, 0.001 respectively), whereas histologic grade was important for OS (P<0.001). Kaplan Meier curves showed CK17 positivity to impact adversely on DFS (P=0.003) and OS (P=0.014), whereas CD117 positive staining was accompanied by diminished OS (P=0.036). SMA expression in TNBC however, revealed a trend for improved DFS (P=0.05). Our findings indicate that basal-like TNBC are associated with adverse clinicopathologic parameters, and that individual biologic markers of CK17, CD117, and SMA have prognostic implications on survival. Possibilities exist for future targeted therapy for this challenging group of breast cancers.

Immunohistochemical expression of hormone receptors in invasive breast carcinoma: correlation of results of H-score with pathological parameters.

Summary The results of H‐scores of oestrogen and progesterone receptor (ER and PR) expression in 150 invasive breast cancers were correlated with conventional pathological prognostic parameters: tumour size, histological grade and subtype, lymph node status, lymphovascular invasion, Nottingham Prognostic Index (NPI) and pathological stage. ER and PR status was determined by immunohistochemical staining of sections cut from archival paraffin‐embedded tissue blocks. We defined positive receptor expression as a H‐score of 50 and above. Our findings revealed ER and PR positivity in 98 (65%) and 52 (35%) cases, respectively. Fiftyone (34%) ER‐positive cases also showed PR expression, while 51 (34%) tumours were negative for both ER and PR. Positive expression for ER and PR was significantly correlated with histological grade (P < 0.0005), mitotic score (P < 0.05) and nuclear pleomorphism (P < 0.05). When we used the relatively simpler method of a cut off of at least 10% tumour cell nuclear staining of moderate or greater intensity as positive receptor status, we found that it agreed well with results of the H‐score, a more quantitative method of assessment.

TP53 Genomic Status Regulates Sensitivity of Gastric Cancer Cells to the Histone Methylation Inhibitor 3-Deazaneplanocin A (DZNep)

Purpose: DZNep (3-deazaneplanocin A) depletes EZH2, a critical component of polycomb repressive complex 2 (PRC2), which is frequently deregulated in cancer. Despite exhibiting promising anticancer activity, the specific genetic determinants underlying DZNep responsiveness in cancer cells remain largely unknown. We sought to determine molecular factors influencing DZNep response in gastric cancer. Experimental Design: Phenotypic effects of DZNep were evaluated in a panel of gastric cancer cell lines. Sensitive lines were molecularly interrogated to identify potential predictors of DZNep responsiveness. The functional importance of candidate predictors was evaluated using short hairpin RNA (shRNA) and siRNA technologies. Results: DZNep depleted PRC2 pathway components in almost all gastric cancer lines, however, only a subset of lines exhibited growth inhibition upon treatment. TP53 genomic status was significantly associated with DZNep cellular responsiveness, with TP53 wild-type (WT) lines being more sensitive (P < 0.001). In TP53-WT lines, DZNep stabilized p53 by reducing ubiquitin conjugation through USP10 upregulation, resulting in activation of canonical p53 target genes. TP53 knockdown in TP53-WT lines attenuated DZNep sensitivity and p53 target activation, showing the functional importance of an intact p53 pathway in regulating DZNep cellular sensitivity. In primary human gastric cancers, EZH2 expression was negatively correlated with p53 pathway activation, suggesting that higher levels of EZH2 may repress p53 activity. Conclusion: Our results highlight an important role for TP53 genomic status in influencing DZNep response in gastric cancer. Clinical trials evaluating EZH2-targeting agents such as DZNep should consider stratifying patients with gastric cancer by their TP53 genomic status. Clin Cancer Res; 18(15); 4201–12. ©2012 AACR.