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Adjuvant chemotherapy after surgery improves survival of patients with stage II–III, resectable gastric cancer. However, the overall survival benefit observed after adjuvant chemotherapy is moderate, suggesting that not all patients with resectable gastric cancer treated with adjuvant chemotherapy benefit from it. We aimed to develop and validate a predictive test for adjuvant chemotherapy response in patients with resectable, stage II–III gastric cancer. In this multi-cohort, retrospective study, we developed through a multi-step strategy a predictive test consisting of two rule-based classifier algorithms with predictive value for adjuvant chemotherapy response and prognosis. Exploratory bioinformatics analyses identified biologically relevant candidate genes in gastric cancer transcriptome datasets. In the discovery analysis, a four-gene, real-time RT-PCR assay was developed and analytically validated in formalin-fixed, paraffin-embedded (FFPE) tumour tissues from an internal cohort of 307 patients with stage II–III gastric cancer treated at the Yonsei Cancer Center with D2 gastrectomy plus adjuvant fluorouracil-based chemotherapy (n=193) or surgery alone (n=114). The same internal cohort was used to evaluate the prognostic and chemotherapy response predictive value of the single patient classifier genes using associations with 5-year overall survival. The results were validated with a subset (n=625) of FFPE tumour samples from an independent cohort of patients treated in the CLASSIC trial (NCT00411229), who received D2 gastrectomy plus capecitabine and oxaliplatin chemotherapy (n=323) or surgery alone (n=302). The primary endpoint was 5-year overall survival. We identified four classifier genes related to relevant gastric cancer features (GZMB, WARS, SFRP4, and CDX1) that formed the single patient classifier assay. In the validation cohort, the prognostic single patient classifier (based on the expression of GZMB, WARS, and SFRP4) identified 79 (13%) of 625 patients as low risk, 296 (47%) as intermediate risk, and 250 (40%) as high risk, and 5-year overall survival for these groups was 83·2% (95% CI 75·2–92·0), 74·8% (69·9–80·1), and 66·0% (60·1–72·4), respectively (p=0·012). The predictive single patient classifier (based on the expression of GZMB, WARS, and CDX1) assigned 281 (45%) of 625 patients in the validation cohort to the chemotherapy-benefit group and 344 (55%) to the no-benefit group. In the predicted chemotherapy-benefit group, 5-year overall survival was significantly improved in those patients who had received adjuvant chemotherapy after surgery compared with those who received surgery only (80% [95% CI 73·5–87·1] vs 64·5% [56·8–73·3]; univariate hazard ratio 0·47 [95% CI 0·30–0·75], p=0·0015), whereas no such improvement in 5-year overall survival was observed in the no-benefit group (72·9% [66·5–79·9] in patients who received chemotherapy plus surgery vs 72·5% [65·8–79·9] in patients who only had surgery; 0·93 [0·62–1·38], p=0·71). The predictive single patient classifier groups (chemotherapy benefit vs no-benefit) could predict adjuvant chemotherapy benefit in terms of 5-year overall survival in the validation cohort (pinteraction=0·036 in univariate analysis). Similar results were obtained in the internal evaluation cohort. The single patient classifiers validated in this study provide clinically important prognostic information independent of standard risk-stratification methods and predicted chemotherapy response after surgery in two independent cohorts of patients with resectable, stage II–III gastric cancer. The single patient classifiers could complement TNM staging to optimise decision making in patients with resectable gastric cancer who are eligible for adjuvant chemotherapy after surgery. Further validation of these results in prospective studies is warranted. Ministry of ICT and Future Planning; Ministry of Trade, Industry, and Energy; and Ministry of Health and Welfare.

Anaplastic thyroid carcinoma (ATC) is an aggressive malignant tumor composed of undifferentiated thyroid follicular cells. Pathological diagnosis of ATC can be challenging as the tumor may show morphological overlap with other neoplasms with anaplastic morphology. Immunohistochemical demonstration of thyroid origin facilitates the diagnosis of ATC. Previous studies using the polyclonal anti-PAX8 antibody 10336-1-AP suggested that PAX8 was the most sensitive marker, expressed in up to 80% of ATC. According to a 2018 NordiQC report, the monoclonal anti-PAX8 antibody MRQ-50 has become the most commonly used anti-PAX8 antibody worldwide. However, validation of this antibody in ATC is lacking. In this study, we recruited 182 ATC cases from seven institutions. Pathology slides were subjected to histology review. PAX8 immunohistochemistry using the MRQ-50 antibody was performed in whole tissue slides (n = 147) or tissue microarray sections (n = 35). We found PAX8 expression in 54.4% of the cases, which was significantly lower than those reported in prior studies with the polyclonal antibody. PAX8 expression was positively correlated with the presence of an epithelial pattern (63.6% vs 37.5%, p = 0.0008) and a coexisting differentiated thyroid carcinoma component (71.6% vs 44.3%, p = 0.0004), but was not associated with age, gender, specimen type, or presence of giant cell and sarcomatoid patterns. In conclusion, we demonstrated PAX8 expression using the monoclonal antibody MRQ-50 in only half of the cases in a large ATC series. Pathologists should be aware that PAX8 expression in ATC is less than those reported in early studies to avoid misdiagnosis.

KCI Citation Count: 2

With the advance in personalized therapeutic strategies in patients with breast cancer, there is an increasing need for biomarker-guided therapy. Although the immunogenicity of breast cancer has not been strongly considered in research or practice, tumor-infiltrating lymphocytes (TILs) are emerging as biomarkers mediating tumor response to treatments. Earlier studies have provided evidence that the level of TILs has prognostic value and the potential for predictive value, particularly in triple-negative and human epidermal growth factor receptor 2-positive breast cancer. Moreover, the level of TILs has been associated with treatment outcome in patients undergoing neoadjuvant chemotherapy. To date, no standardized methodology for measuring TILs has been established. In this article, we review current issues and clinical evidence for the use of TILs in breast cancer.

The incidence of endometrial cancer is rapidly increasing worldwide, and its molecular classification has gained importance for new therapeutic approaches. This study sought to examine the clinicopathologic features and immune markers associated with the DNA mismatch repair (MMR) status and MLH1 promoter methylation status of endometrial cancer patients. A total of 173 patients with primary endometrial cancer who had received a hysterectomy were evaluated for four MMR proteins (MLH1, MSH2, MSH6, and PMS2), immune markers (CD8, programmed cell death protein 1 (PD-1), and programmed death-ligand 1 (PD-L1)) and p53 by immunohistochemistry (IHC), followed by an MLH1 methylation test. Patients were classified into MMR deficiency or proficiency, sporadic cancer, or probable Lynch syndrome (PLS), and the clinicopathologic features (including the expression of peritumoral immune markers) and prognosis of each group were compared. Patients with MMR deficiency or PLS showed an increase in immune markers compared those with MMR proficiency or sporadic cancer, respectively, and PLS demonstrated higher immune marker expression than MLH1 promoter methylation. Regarding prognosis, patients with MMR deficiency showed significant adverse overall survival (OS) when in stages I and II. Practical molecular classifications based on p53 staining results, in addition to MMR or PLS status, revealed an increased predictive ability for OS compared with the European Society of Medical Oncologists (ESMO) risk groups. The results of this study suggest that PLS may be a better candidate for an immune checkpoint inhibitor than MMR deficiency. The practical molecular classification contributes not only to the screening of Lynch syndrome, but also assists in predicting the prognosis in endometrial cancer.

Ultrasound-guided fine-needle aspiration (FNA) cytology is the most widely used screening and diagnostic method for thyroid nodules. Although Western guidelines for managing thyroid nodules and the Bethesda System for Reporting Thyroid Cytopathology are widely available throughout Asia, the clinical practices in Asia vary from those of Western countries. Accordingly, the Working Group of Asian Thyroid FNA Cytology encouraged group members to publish their works jointly with the same topic. The articles in this special issue focused on the history of thyroid FNA, FNA performers and interpreters, training programs of cytopathologists and cytotechnicians, staining methods, the reporting system of thyroid FNA, quality assurance programs, ancillary testing, and literature review of their own country's products. Herein, we provide a brief overview of thyroid FNA practices in China, India, Japan, Korea, the Philippines, Taiwan, and Thailand.

When differential diagnosis is difficult in thyroid follicular lesions with overlapping histological features, the immunohistochemical staining can help confirm the diagnosis. We aimed to evaluate the effectiveness of rapid immunohistochemical stains of CD56 and cytokeratin 19 on frozen sections of thyroid follicular lesion and explore the possible gains and limitations of the practice. Eighty-six nodules of 79 patients whose intraoperative frozen sections were selected as the control group, and 53 nodules of 48 patients whose intraoperative frozen sections were subject to rapid immunohistochemistry were selected as the study group. Five nodules (6%) in the control group were diagnosed as follicular neoplasm and six nodules (7%) were deferred. In the study group, six nodules (11%) were follicular neoplasm and none were deferred. Three nodules (4%) in the control group showed diagnostic discrepancy between the frozen and permanent diagnoses, but none in the study group. The average turnaround time for the frozen diagnosis of the control group was 24 minutes, whereas it was 54 minutes for the study group. Intraoperative rapid immunohistochemical stains significantly decreased the diagnostic discrepancy in this study. Considering the adverse effects of indefinite frozen diagnosis or discrepancy with permanent diagnoses, the intraoperative rapid immunohistochemical stain can help to accurately diagnose and hence provide guidance to surgical treatment.

We reviewed the current status of thyroid fine-needle aspiration cytology (FNAC) in Korea. Thyroid aspiration biopsy was first introduced in Korea in 1977. Currently, radiologists aspirate the thyroid nodule under the guidance of ultrasonography, and cytologic interpretation is only legally approved when a cytopathologist makes the diagnosis. In 2008, eight thyroid-related societies came together to form the Korean Thyroid Association. The Korean Society for Cytopathology and the endocrine pathology study group of the Korean Society for Pathologists have been updating the cytologic diagnostic guidelines. The Bethesda System for Reporting Thyroid Cytopathology was first introduced in 2009, and has been used by up to 94% of institutions by 2016. The average diagnosis rates are as follows for each category: I (12.4%), II (57.9%), III (10.4%), IV (2.9%), V (3.7%), and VI (12.7%). The malignancy rates in surgical cases are as follows for each category: I (28.7%), II (27.8%), III (50.6%), IV (52.3%), V (90.7%), and VI (100.0%). Liquid-based cytology has been used since 2010, and it was utilized by 68% of institutions in 2016. The categorization of thyroid lesions into \"atypia of undetermined significance\" or \"follicular lesion of undetermined significance\" is necessary to draw consensus in our society. Immunocytochemistry for galectin-3 and BRAF is used. Additionally, a molecular test for BRAF in thyroid FNACs is actively used. Core biopsies were performed in only 44% of institutions. Even the institutions that perform core biopsies only perform them for less than 3% of all FNACs. However, only 5% of institutions performed core biopsies up to three times more than FNAC.

Background Radioiodine (RI) ablation following thyroid-stimulating hormone suppression is an effective treatment for papillary thyroid cancer (PTC), typically leading to favorable outcomes. However, RI-refractory tumors exhibit aggressive behavior and poor prognoses. Recent studies highlight the role of genetic abnormalities in PTC signaling pathways, including the activation of telomerase reverse transcriptase (TERT), and the correlation of mutations with adverse outcomes. Methods This study analyzed mutations in BRAF V600E and the TERT-promoter genes, comparing clinicopathological features between RI-refractory and RI-responsive PTCs. Among 82 RI-refractory patients, formalin-fixed, paraffin-embedded tissues from initial surgeries were available for 26. Another 89 without distant metastasis over 5 years formed a matched RI-responsive control group. Results Histopathologically, RI-refractory PTCs showed increased frequencies of small tumor clusters without fibrovascular cores, hobnail features, and a high height-to-width ratio of tumor cells. These tumors were more likely to exhibit necrosis, mitosis, lymph node metastasis, extrathyroidal extension, and involvement of resection margins. TERT-promoter mutations were statistically significantly associated with these aggressive clinicopathologic features. Immunohistochemically, decreased expression of sodium iodide symporter and thyroglobulin stimulating hormone receptor proteins was common in RI-refractory PTCs, along with lower levels of oncogenic proteins such as vascular endothelial cell growth factor, vascular endothelial cell growth factor receptor 2, and nuclear factor kappa-light-chain-enhancer of activated B cells. Total loss of PTEN expression was occasionally observed. In contrast, all cases tested positive for cytoplasmic β-catenin. Conclusions RI-refractory PTCs are linked to TERT mutations and exhibit specific aggressive histopathologic features, particularly in tumor centers.

Background: Radioiodine (RI) ablation following thyroid-stimulating hormone suppression is an effective treatment for papillary thyroid cancer (PTC), typically leading to favorable outcomes. However, RI-refractory tumors exhibit aggressive behavior and poor prognoses. Recent studies highlight the role of genetic abnormalities in PTC signaling pathways, including the activation of telomerase reverse transcriptase (TERT), and the correlation of mutations with adverse outcomes. Methods: This study analyzed mutations in BRAF V600E and the TERT-promoter genes, comparing clinicopathological features between RI-refractory and RI-responsive PTCs. Among 82 RI-refractory patients, formalin-fixed, paraffin-embedded tissues from initial surgeries were available for 26. Another 89 without distant metastasis over 5 years formed a matched RI-responsive control group. Results: Histopathologically, RI-refractory PTCs showed increased frequencies of small tumor clusters without fibrovascular cores, hobnail features, and a high height-to-width ratio of tumor cells. These tumors were more likely to exhibit necrosis, mitosis, lymph node metastasis, extrathyroidal extension, and involvement of resection margins. TERT-promoter mutations were statistically significantly associated with these aggressive clinicopathologic features. Immunohistochemically, decreased expression of sodium iodide symporter and thyroglobulin stimulating hormone receptor proteins was common in RI-refractory PTCs, along with lower levels of oncogenic proteins such as vascular endothelial cell growth factor, vascular endothelial cell growth factor receptor 2, and nuclear factor kappa-light-chain-enhancer of activated B cells. Total loss of PTEN expression was occasionally observed. In contrast, all cases tested positive for cytoplasmic β-catenin. Conclusions: RI-refractory PTCs are linked to TERT mutations and exhibit specific aggressive histopathologic features, particularly in tumor centers.