A Prospective Validation and Observer Performance Study of a Deep Learning Algorithm for Pathologic Diagnosis of Gastric Tumors in Endoscopic Biopsies

PURPOSE

Gastric cancer remains the leading cause of cancer-related deaths in Northeast Asia. Population-based endoscopic screenings in the region have yielded successful results in early detection of gastric tumors. Endoscopic screening rates are continuously increasing, and there is a need for an automatic computerized diagnostic system to reduce the diagnostic burden. In this study, we developed an algorithm to classify gastric epithelial tumors automatically and assessed its performance in a large series of gastric biopsies and its benefits as an assistance tool.

EXPERIMENTAL DESIGN

Using 2,434 whole-slide images, we developed an algorithm based on convolutional neural networks to classify a gastric biopsy image into one of three categories: negative for dysplasia (NFD), tubular adenoma, or carcinoma. The performance of the algorithm was evaluated by using 7,440 biopsy specimens collected prospectively. The impact of algorithm-assisted diagnosis was assessed by six pathologists using 150 gastric biopsy cases.

RESULTS

Diagnostic performance evaluated by the AUROC curve in the prospective study was 0.9790 for two-tier classification: negative (NFD) versus positive (all cases except NFD). When limited to epithelial tumors, the sensitivity and specificity were 1.000 and 0.9749. Algorithm-assisted digital image viewer (DV) resulted in 47% reduction in review time per image compared with DV only and 58% decrease to microscopy.

CONCLUSIONS

Our algorithm has demonstrated high accuracy in classifying epithelial tumors and its benefits as an assistance tool, which can serve as a potential screening aid system in diagnosing gastric biopsy specimens.

Expression of embryonal stem cell transcription factors in breast cancer: Oct4 as an indicator for poor clinical outcome and tamoxifen resistance

The transcription factors of embryonic stem cells, such as Oct4, Sox2, Nanog, Bmi1, and Klf4, are known to be associated with stemness, epithelial–mesenchymal transition and aggressive tumor behavior. This study was designed to evaluate the clinicopathological significance of their expression in breast cancer. Immunohistochemistry for Oct4, Sox2, Nanog, Bmi1, and Klf4 was performed in 319 cases of invasive breast cancer. The relationship between the expression of these markers and clinicopathologic features of the tumors, including breast cancer stem cell phenotype and epithelial–mesenchymal transition marker expression, and their prognostic value in breast cancer, were analyzed. Expression of Oct4 and Sox2 was commonly associated with high histologic grade and high Ki-67 index in the whole group and in the hormone receptor-positive subgroup. On the other hand, expression of Nanog, Bmi1, and Klf4 was inversely correlated with aggressive features of the breast cancer. Oct4 expression was associated with ALDH1 expression but not with epithelial–mesenchymal transition marker expression. In survival analysis, Oct4 expression was independently associated with poor prognosis in the whole group and in the hormone receptor-positive subgroup, but not in hormone receptor-negative subgroup. Particularly, Oct4 expression was associated with poor clinical outcome in patients with hormone receptor-positive breast cancer treated with tamoxifen. Our results indicate that Oct4 expression is associated with aggressive features, ALDH1 expression, tamoxifen resistance and poor clinical outcomes in hormone receptor-positive breast cancer, and thus may be useful as a predictive and prognostic marker in this subgroup of breast cancer.

MicroRNA-222 Expression as a Predictive Marker for Tumor Progression in Hormone Receptor-Positive Breast Cancer

Purpose

The microRNA-221/222 (miR-221/222) gene cluster has been reported to be associated with the promotion of epithelial-mesenchymal transition (EMT), downregulation of estrogen receptor-α, and tamoxifen resistance in breast cancer. We studied the expression of miR-222 in human breast cancer samples to analyze its relationship with clinicopathologic features of the tumor, including estrogen receptor status, expression of EMT markers, and clinical outcomes.

Methods

Quantitative real-time polymerase chain reaction was performed to detect the expression of miR-222 in 197 invasive breast cancers. Expression of EMT markers (vimentin, smooth muscle actin, osteonectin, N-cadherin, and E-cadherin) was evaluated using immunohistochemistry.

Results

High miR-222 levels were associated with high T stage, high histologic grade, high Ki-67 proliferation index, and HER2 gene amplification. Its expression was significantly higher in the luminal B and human epidermal growth factor receptor 2-positive (HER2+) subtypes than in the luminal A and triple-negative subtypes. In the hormone receptor-positive subgroup, there was a significant negative correlation between miR-222 and estrogen receptor expression, and miR-222 expression was associated with EMT marker expression. In the group as a whole, high miR-222 expression was not associated with clinical outcome. However, subgroup analyses by hormone receptor status revealed that high miR-222 expression was a poor prognostic factor in the hormone receptor-positive subgroup, but not in the hormone receptor-negative subgroup.

Conclusion

This study showed that miR-222 is associated with down-regulation of the estrogen receptor, EMT, and tumor progression in hormone receptor-positive breast cancer, indicating that miR-222 might be associated with endocrine therapy resistance and poor clinical outcome in hormone receptor-positive breast cancer.

Association between basal-like phenotype and BRCA1/2 germline mutations in Korean breast cancer patients

INTRODUCTION

BRCA mutation testing allows index patients and their families to be provided with appropriate cancer risk-reduction strategies. Because of the low prevalence of BRCA mutations in unselected breast cancer patients and the high cost of genetic testing, it is important to identify the subset of women who are likely to carry BRCA mutations. In the present study, we examined the association between BRCA1/2 germline mutations and the immunohistochemical features of breast cancer.

METHODS

In a retrospective review of 498 breast cancer patients who had undergone BRCA testing at Seoul National University Bundang Hospital between July 2003 and September 2012, we gathered immunohistochemical information on estrogen receptor (er), progesterone receptor (pr), her2 (human epidermal growth factor receptor 2), cytokeratin 5/6, egfr (epidermal growth factor receptor), and p53 status.

RESULTS

Among the 411 patients eligible for the study, 50 (12.2%) had germline mutations in BRCA1 or BRCA2. Of the 93 patients with triple-negative breast cancer (tnbc), 25 with BRCA1/2 mutations were identified (BRCA1, 20.4%; BRCA2, 6.5%). On univariate analysis, er, pr, cytokeratin 5/6, egfr, and tnbc were found to be related to BRCA1 mutations, but on multivariate analysis, only tnbc was significantly associated with BRCA1 mutations. Among patients with early-onset breast cancer or with a family history of breast or ovarian cancer, BRCA1 mutations were significantly more prevalent in the tnbc group than in the non-tnbc group.

CONCLUSIONS

In the present study, tnbc was the only independent predictor of BRCA1 mutation in patients at high risk of hereditary breast and ovarian cancers. Other histologic features of basal-like breast cancer did not improve the estimate of BRCA1 mutation risk.

Prognostic value of tumor-associated macrophages according to histologic locations and hormone receptor status in breast cancer

Tumor-associated macrophages (TAMs) are involved in tumor progression by promoting epithelial-mesenchymal transition (EMT), tumor cell invasion, migration and angiogenesis. However, in breast cancer, the clinical relevance of the TAM infiltration according to distinct histologic locations (intratumoral vs. stromal) and hormone receptor status is unclear. We investigated the significance of the levels of TAM infiltration in distinct histologic locations in invasive breast cancer. We also examined the relationship of the TAM levels with the clinicopathologic features of tumors, expression of EMT markers, and clinical outcomes. Finally, we analyzed the prognostic value of TAM levels according to hormone receptor status. High levels of infiltration of intratumoral, stromal and total TAMs were associated with high histologic grade, p53 overexpression, high Ki-67 proliferation index and negative hormone receptor status. Infiltration of TAMs was also correlated with overexpression of vimentin, smooth muscle actin and alteration of β-catenin. Overall, a high level of infiltration of intratumoral TAMs was associated with poor disease-free survival, and was found to be an independent prognostic factor. In subgroup analyses by hormone receptor status, a high level of infiltration of intratumoral TAM was an independent prognostic factor in the hormone receptor-positive subgroup, but not in the hormone-receptor negative subgroup. Our findings suggest that intratumoral TAMs play an important role in tumor progression in breast cancer, especially in the hormone receptor-positive group, and the level of TAM infiltration may be used as a prognostic factor and even a therapeutic target in breast cancer.

Alu and LINE-1 hypomethylation is associated with HER2 enriched subtype of breast cancer

The changes in DNA methylation status in cancer cells are characterized by hypermethylation of promoter CpG islands and diffuse genomic hypomethylation. Alu and long interspersed nucleotide element-1 (LINE-1) are non-coding genomic repetitive sequences and methylation of these elements can be used as a surrogate marker for genome-wide methylation status. This study was designed to evaluate the changes of Alu and LINE-1 hypomethylation during breast cancer progression from normal to pre-invasive lesions and invasive breast cancer (IBC), and their relationship with characteristics of IBC. We analyzed the methylation status of Alu and LINE-1 in 145 cases of breast samples including normal breast tissue, atypical ductal hyperplasia/flat epithelial atypia (ADH/FEA), ductal carcinoma in situ (DCIS) and IBC, and another set of 129 cases of IBC by pyrosequencing. Alu methylation showed no significant changes during multistep progression of breast cancer, although it tended to decrease during the transition from DCIS to IBC. In contrast, LINE-1 methylation significantly decreased from normal to ADH/FEA, while it was similar in ADH/FEA, DCIS and IBC. In IBC, Alu hypomethylation correlated with negative estrogen receptor (ER) status, and LINE-1 hypomethylation was associated with negative ER status, ERBB2 (HER2) amplification and p53 overexpression. Alu and LINE-1 methylation status was significantly different between breast cancer subtypes, and the HER2 enriched subtype had lowest methylation levels. In survival analyses, low Alu methylation status tended to be associated with poor disease-free survival of the patients. Our findings suggest that LINE-1 hypomethylation is an early event and Alu hypomethylation is probably a late event during breast cancer progression, and prominent hypomethylation of Alu and LINE-1 in HER2 enriched subtype may be related to chromosomal instability of this specific subtype.

Epithelial-mesenchymal transition increases during the progression of in situ to invasive basal-like breast cancer

Epithelial-mesenchymal transition (EMT) is known to play an important role in breast cancer invasion and metastatic progression. However, the pattern of expression of EMT markers in the progression from in situ to invasive breast carcinoma is not clear. To investigate this, we performed immunohistochemical analyses of EMT markers (expression of vimentin, smooth muscle actin, osteonectin, and N-cadherin; loss of E-cadherin; alteration of β-catenin), breast cancer stem cell (CSC) markers (CD44(+)/CD24(-), ALDH1), and CD146, an EMT inducer, in invasive carcinomas and ductal carcinoma in situ (DCIS) of the breast. Expression of EMT markers was closely associated with the basal-like subtype and CSC phenotype in invasive carcinoma but not in pure DCIS, except for vimentin. The expression of smooth muscle actin and N-cadherin, loss of E-cadherin, and alteration of β-catenin were significantly higher in invasive carcinomas than in pure DCIS (P = .015, P = .029, P = .001, and P = .007, respectively). Subgroup analyses revealed greater loss of E-cadherin and alteration of β-catenin in invasive carcinoma than in pure DCIS in basal-like subtype (P = .001) but not in non-basal-like subtypes. Moreover, expression of EMT markers and CD146 was higher in the invasive than in the DCIS component of basal-like cancers. Our study confirmed that EMT is an intrinsic characteristic of basal-like subtype and is associated with CSC phenotype. Furthermore, we showed higher expression of EMT markers in invasive carcinomas than in pure DCIS, especially in basal-like subtype, and in the invasive component of basal-like breast cancers, suggesting that EMT may be involved in the progression from in situ to invasive basal-like breast cancers.

The Histologic Cut-off Point for Adjacent and Remote Non-neoplastic Liver Parenchyma of Hepatocellular Carcinoma in Chronic Hepatitis B Patients

Background

The molecular profile of peritumoral non-neoplastic liver parenchyma (PNLP) has recently been suggested as predictive factor of early and late recurrence of hepatocellular carcinoma (HCC). However, there is no definite cut-off point for tumor-free PNLP in terms of either histological or molecular changes. Therefore, our aim is to determine the numerical cut-off point for separating adjacent PNLP and remote PNLP in histopathologic perspective.

Methods

Peritumoral tissues from 20 resected HCC patients were sampled from 0 to 40 mm distance from the tumor border (divided into 5-mm columns). Histopathologic parameters such as necroinflammatory activity, fibrosis, bile ductular reaction, hepatic venulitis, peliosis, and steatosis were compared between each column.

Results

The morphologic changes just adjacent to the tumor were notably severe and faded with distance. The parenchyma within 10 mm of the tumor showed significantly severe inflammation, fibrosis, peliosis and hepatic venulitis compared with those from farther areas. The histopathologic changes of the parenchyma became stable beyond 20 mm.

Conclusions

Results of this study revealed that the parenchyma within 10 mm distance from the tumor, or adjacent PNLP, has histopathologic changes that are directly affected by the tumor, and the parenchyma beyond 20 mm as the remote PNLP without tumor effect.