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In recent years, next-generation sequencing (NGS)-based genetic testing has become crucial in cancer care. While its primary objective is to identify actionable genetic alterations to guide treatment decisions, its scope has broadened to encompass aiding in pathological diagnosis and exploring resistance mechanisms. With the ongoing expansion in NGS application and reliance, a compelling necessity arises for expert consensus on its application in solid cancers. To address this demand, the forthcoming recommendations not only provide pragmatic guidance for the clinical use of NGS but also systematically classify actionable genes based on specific cancer types. Additionally, these recommendations will incorporate expert perspectives on crucial biomarkers, ensuring informed decisions regarding circulating tumor DNA panel testing. [ABSTRACT FROM AUTHOR]

Purpose The benefit of adjuvant chemotherapy following curative-intent surgery in pancreatic ductal adenocarcinoma (PDAC) patients who had received neoadjuvant FOLFIRINOX is unclear. This study aimed to assess the survival benefit of adjuvant chemotherapy in this patient population. Materials and Methods This retrospective study included 218 patients with localized non-metastatic PDAC who received neoadjuvant FOLFIRINOX and underwent curative-intent surgery (R0 or R1) between January 2017 and December 2020. The association of adjuvant chemotherapy with disease-free survival (DFS) and overall survival (OS) was evaluated in overall patients and in the propensity score matched (PSM) cohort. Subgroup analysis was conducted according to the pathology-proven lymph node status. Results Adjuvant chemotherapy was administered to 149 patients (68.3%). In the overall cohort, the adjuvant chemotherapy group had significantly improved DFS and OS compared to the observation group (DFS: median, 13.8 months [95% confidence interval (CI), 11.0 to 19.1] vs. 8.2 months [95% CI, 6.5 to 12.0]; p < 0.001; and OS: median, 38.0 months [95% CI, 32.2 to not assessable] vs. 25.7 months [95% CI, 18.3 to not assessable]; p=0.005). In the PSM cohort of 57 matched pairs of patients, DFS and OS were better in the adjuvant chemotherapy group than in the observation group (p < 0.001 and p=0.038, respectively). In the multivariate analysis, adjuvant chemotherapy was a significant favorable prognostic factor (vs. observation; DFS: hazard ratio [HR], 0.51 [95% CI, 0.36 to 0.71; p < 0.001]; OS: HR, 0.45 [95% CI, 0.29 to 0.71; p < 0.001]). Conclusion Among PDAC patients who underwent surgery following neoadjuvant FOLFIRINOX, adjuvant chemotherapy may be associated with improved survival. Randomized studies should be conducted to validate this finding. [ABSTRACT FROM AUTHOR]

Purpose Guidelines recommend that non-small cell lung cancer (NSCLC) patients with suspected hilar lymph node (LN) metastases should undergo invasive mediastinal LN staging prior to surgical treatment via endosonography. We evaluated the diagnostic performance of endosonography for detecting occult mediastinal metastases (OMM) and determined the factors associated with OMM in NSCLC patients with radiological N1. Materials and Methods Patients with confirmed primary NSCLC with radiological N1 who underwent endosonography for nodal staging assessment from January 2013 to December 2019 were retrospectively analyzed. Results The prevalence of OMM was found to be 83/279 (29.7%) and only 38.6% (32/83) were diagnosed via endosonography. However, five of them were confirmed as N3 by endosonography. The overall diagnostic sensitivity, negative predictive value, accuracy, and area under the curve of endosonography were 38.6%, 79.4%, 81.7%, and 0.69, respectively. In multivariable analysis, central tumor (adjusted odds ratio [aOR], 2.05; 95% confidence interval [CI], 1.15 to 3.68; p=0.016), solid tumor (aOR, 10.24; 95% CI, 1.32 to 79.49; p=0.026), and adenocarcinoma (aOR, 3.01; 95% CI, 1.63 to 5.55; p < 0.001) were related to OMM in radiological N1 NSCLC patients. Conclusion Although the sensitivity of endosonography for detecting OMM was only 40%, the prevalence of OMM was not low (30%) and some cases even turned out to be N3 diseases. Clinicians should be aware that OMM may be more likely in patients with central, solid, and adenocarcinomatous tumor when performing nodal staging in radiological N1 NSCLC via endosonography. [ABSTRACT FROM AUTHOR]

Purpose This study aimed to investigate cumulative incidence and risk factors associated with chronic pulmonary infection (CPI) development after radiotherapy for lung cancer. Materials and Methods We retrospectively analyzed 1,872 patients with lung cancer who received radiotherapy for lung cancer from 2010-2014, had a follow-up period of = 3 months after radiotherapy, and did not have CPI at the time of radiotherapy. CPI was defined as pulmonary tuberculosis, non-tuberculous mycobacterial pulmonary disease, chronic pulmonary aspergillosis, or pulmonary actinomycosis. The cumulative incidence of CPI and overall survival (OS) were estimated using the Kaplan-Meier method, and a multivariable Cox proportional hazards analysis was performed to identify risk factors associated with CPI development. Results The median follow-up period was 2.3 years with OS rates of 55.6% and 37.6% at 2 and 5 years, respectively. CPI developed in 59 patients at a median of 1.8 years after radiotherapy, with cumulative incidence rates of 1.1%, 3.4%, 5.0%, and 6.8% at 1, 3, 5, and 7 years, respectively. A lower body mass index, interstitial lung disease, prior pulmonary tuberculosis, larger clinical target volume, history of lung cancer surgery or radiation pneumonitis, and use of inhaled corticosteroids were independent risk factors for CPI development. Conclusion The long-term survival rate of lung cancer patients receiving radiotherapy was not low, but the cumulative incidence of CPI gradually increased to 6.8% at 7 years after radiotherapy. Therefore, close monitoring of CPI development is required in surviving patients with risk factors. [ABSTRACT FROM AUTHOR]

Purpose The treatment of male breast cancer (MBC) has been extrapolated from female breast cancer (FBC) because of its rarity despite their different clinicopathologic characteristics. We aimed to investigate the distribution of intrinsic subtypes based on immunohistochemistry, their clinical impact, and treatment pattern in clinical practice through a multicenter study in Korea. Materials and Methods We retrospectively analyzed clinical data of 248 MBC patients from 18 institutions across the country from January 1995 to July 2016. Results The median age of MBC patients was 63 years (range, 25 to 102 years). Among 148 intrinsic subtype classified patients, 61 (41.2%), 44 (29.7%), 29 (19.5%), and 14 (9.5%) were luminal A, luminal B, human epidermal growth factor receptor 2, and triple-negative breast cancer, respectively. Luminal A subtype showed trends for superior survival compared to other subtypes. Most hormone receptor-positive patients (166 patients, 82.6%) received adjuvant endocrine treatment. Five-year completion of adjuvant endocrine treatment was associated with superior disease-free survival (DFS) in patients classified with an intrinsic subtype (hazard ratio [HR], 0.15; 95% confidence interval [CI], 0.04 to 0.49; p=0.002) and in all patients (HR, 0.16; 95% CI, 0.05 to 0.54; p=0.003). Conclusion Distribution of subtypes of MBC was similar to FBC and luminal type A was most common. Overall survival tended to be improved for luminal A subtype, although there was no statistical significance. Completion of adjuvant endocrine treatment was associated with prolonged DFS in intrinsic subtype classified patients. MBC patients tended to receive less treatment. MBC patients should receive standard treatment according to guidelines as FBC patients. [ABSTRACT FROM AUTHOR]

Purpose The role of epidermal growth factor receptor–tyrosine kinase inhibitors (EGFR-TKIs) in the management of persistent subsolid nodules (SSNs) is unclear. This study aimed to investigate the impact of EGFR-TKIs on concurrent SSNs in patients with stage IV non–small cell lung cancer (NSCLC). Materials and Methods Patients who received an EGFR-TKI for at least 1 month for stage IV NSCLC and had concurrent SSN(s) that had existed for at least 3 months on chest computed tomography were included in this retrospective study. Size change of each nodule before and after EGFR-TKI therapies were evaluated using a cutoff value of 2 mm; increase (≥ 2 mm), decrease (≤ –2 mm), and no change (–2 mm < size change < +2 mm). Results A total of 77 SSNs, 51 pure ground-glass (66.2%) and 26 part-solid nodules (33.8%), were identified in 59 patients who received gefitinib (n=45) and erlotinib (n=14). Among 58 EGFR mutation analysis performed for primary lung cancer, 45 (77.6%) were EGFR mutant. The proportions of decrease group were 19.5% (15/77) on per-nodule basis and 25.4% (15/59) on per-patient basis. Four SSNs (5.2%) disappeared completely. On per-patient based multivariable analysis, EGFR exon 19 deletion positivity for primary lung cancer was associated with a decrease after initial EGFR-TKI therapy (adjusted odds ratio, 4.29; 95% confidence interval, 1.21 to 15.29; p=0.025). Conclusion Approximately 20% of the concurrent SSNs decreased after the initial EGFR-TKI therapy. EGFR exon 19 deletion positivity for primary lung cancer was significantly associated with the size change of concurrent SSNs. [ABSTRACT FROM AUTHOR]

Purpose In hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer (HR+ HER2-MBC), the mainstay treatment options include cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) and everolimus (EVE) in combination with endocrine treatment. This study aims to compare the outcomes of the following treatment sequences: CDK4/6i followed by EVE and EVE followed by CDK4/6i. Materials and Methods Data from HR+ HER2- MBC patients treated between January 2014 and November 2020 with both CDK4/6i and EVE were retrospectively analyzed. Results Among the 88 patients included in the study, 51 received CDK4/6i before EVE (C→E group), and 37 received EVE before CDK4/6i (E→C group) with endocrine treatment. More patients in the E→C group had endocrine resistance (13.7% vs. 40.5%), experienced palliative chemotherapy (7.8% vs. 40.5%), and were heavily treated (treated as ≥ 3rd line, 5.9% vs. 40.5%). Median overall survival was 46.8 months in the C→E group and 38.9 months in the E→C group (p=0.151). Median composite progression-free survival (PFS), defined as the time from the start of the preceding regimen to disease progression on the following regimen or death, was 24.8 months in the C→E group vs. 21.8 months in the E→C group (p=0.681). Median PFS2/PFS1 ratio did not differ significantly between groups (0.5 in the C→E group, 0.6 in the E→C group; p=0.775). Ten patients (11.4%) discontinued EVE, and two patients (2.3%) discontinued CDK4/6i during treatment. Conclusion Although the CDK4/6i-based regimen should be considered as an earlier line of treatment, CDK4/6i- and EVE-based treatments can be valid options in circumstances where the other treatment had been already given. [ABSTRACT FROM AUTHOR]

Next-generation sequencing (NGS) is becoming essential in the fields of precision oncology. With implementation of NGS in daily clinic, the needs for continued education, facilitated interpretation of NGS results and optimal treatment delivery based on NGS results have been addressed. Molecular tumor board (MTB) is multidisciplinary approach to keep pace with the growing knowledge of complex molecular alterations in patients with advanced solid cancer. Although guidelines for NGS use and MTB have been developed in western countries, there is limitation for reflection of Korea's public health environment and daily clinical practice. These recommendations provide a critical guidance from NGS panel testing to final treatment decision based on MTB discussion. [ABSTRACT FROM AUTHOR]

Purpose Patients who have undergone gastrectomy have unique symptoms that are not appropriately assessed using currently available tools. This study developed and validated a symptom-focused quality of life (QoL) questionnaire for patients who have received gastrectomy for gastric cancer. Materials and Methods Based on a literature review, patient interviews, and expert consultation by the KOrean QUality of life in Stomach cancer patients Study group (KOQUSS), the initial item pool was developed. Two large-scale developmental studies were then sequentially conducted for exploratory factor analyses for content validity and item reduction. The final item pool was validated in a separate cohort of patients and assessed for internal consistency, test-retest reliability, construct validity, and clinical validity. Results The initial questionnaire consisted of 46-items in 12 domains. Data from 465 patients at 11 institutions, followed by 499 patients at 13 institutions, were used to conduct item reduction and exploratory factor analyses. The final questionnaire (KOQUSS-40) comprised 40 items within 11 domains. Validation of KOQUSS-40 was conducted on 413 patients from 12 hospitals. KOQUSS-40 was found to have good model fit. The mean summary score of the KOQUSS-40 was correlated with the EORTC QLQ-C30 and STO22 (correlation coefficients, 0.821 and 0.778, respectively). The KOQUSS-40 score was also correlated with clinical factors, and had acceptable internal consistency (> 0.7). Test-retest reliability was greater than 0.8. Conclusion The KOQUSS-40 can be used to assess QoL of gastric cancer patients after gastrectomy and allows for a robust comparison of surgical techniques in clinical trials. [ABSTRACT FROM AUTHOR]

Purpose This study evaluated the efficacy of adjuvant chemotherapy (AC) in patients with resected ampulla of Vater (AoV) carcinoma. Materials and Methods Data from 646 patients who underwent surgical resection at Asan Medical Center between 2000 and 2017 were retrospectively reviewed. Results The median age of the patients was 62 years, and 54.2% were male. Patients were classified into AC group (n=165, 25.5%) and no AC group (n=481, 74.5%). With a median follow-up duration of 88 months, in patients with stage I, II, III, median recurrencefree survival (RFS) was not reached, 44 months, and 15 months, respectively, and the median overall survival (OS) were not reached, 88 months and 35 months, respectively. Despite no statistical significance, RFS and OS were better in stage II patients with AC than in those without AC (median RFS, 151 months vs. 38 months; p=0.156 and median OS, 153 months vs. 74 months; p=0.299). In multivariate analysis for RFS and OS, TNM stage, R1 resection status, presence of lymphovascular invasion, and perineural invasion remained significant factors, whereas AC (hazard ratio [HR], 0.74; 95% confidence interval [CI], 0.54 to 1.00; p=0.052) was marginally related with RFS. After propensity score matching in only stage II/III patients, RFS and OS with AC were numerically longer than those without AC (HR, 0.80; 95% CI, 0.60 to 1.06; p=0.116 and HR, 0.77; 95% CI, 0.56 to 1.06; p=0.111). Conclusion AC with fluoropyrimidine did not improve survival of patients with resected AoV carcinoma. However, multivariate analysis with prognostic factors showed a marginally significant survival benefit with AC. [ABSTRACT FROM AUTHOR]

Purpose The clinical implications of tumor-infiltrating T cell subsets and their spatial distribution in biliary tract cancer (BTC) patients treated with gemcitabine plus cisplatin were investigated. Materials and Methods A total of 52 BTC patients treated with palliative gemcitabine plus cisplatin were included. Multiplexed immunohistochemistry was performed on tumor tissues, and immune infiltrates were separately analyzed for the stroma, tumor margin, and tumor core. Results The density of CD8+ T cells, FoxP3- CD4+ helper T cells, and FoxP3+ CD4+ regulatory T cells was significantly higher in the tumor margin than in the stroma and tumor core. The density of LAG3- or TIM3-expressing CD8+ T cell and FoxP3- CD4+ helper T cell infiltrates was also higher in the tumor margin. In extrahepatic cholangiocarcinoma, there was a higher density of T cell subsets in the tumor core and regulatory T cells in all regions. A high density of FoxP3- CD4+ helper T cells in the tumor margin showed a trend toward better progression-free survival (PFS) (p=0.092) and significantly better overall survival (OS) (p=0.012). In multivariate analyses, a high density of FoxP3- CD4+ helper T cells in the tumor margin was independently associated with favorable PFS and OS. Conclusion The tumor margin is the major site for the active infiltration of T cell subsets with higher levels of LAG3 and TIM3 expression in BTC. The density of tumor margin-infiltrating FoxP3- CD4+ helper T cells may be associated with clinical outcomes in BTC patients treated with gemcitabine plus cisplatin. [ABSTRACT FROM AUTHOR]

Purpose The current standard chemotherapy for advanced biliary tract cancer (BTC) has limited benefit, and novel therapies need to be investigated. Materials and Methods In this prospective cohort study, programmed death ligand-1 (PD-L1)--positive BTC patients who progressed on first-line gemcitabine plus cisplatin were enrolled. Pembrolizumab 200 mg was administered intravenously every 3 weeks. Results Between May 2018 and February 2019, 40 patients were enrolled. Pembrolizumab was given as second-line (47.5%) or ≤ third-line therapy (52.5%). The objective response rate was 10% and 12.5% by Response Evaluation Criteria in Solid Tumor (RECIST) v1.1 and immune-modified RECIST (imRECIST) and median duration of response was 6.3 months. Among patients with progressive disease as best response, one patient (1/20, 5.0%) achieved complete response subsequently. The median progression-free survival (PFS) and overall survival (OS) were 1.5 months (95% confidence interval [CI], 0.0 to 3.0) and 4.3 months (95% CI, 3.5 to 5.1), respectively, and objective response per imRECIST was significantly associated with PFS (p < 0.001) and OS (p=0.001). Tumor proportion score ≥ 50% was significantly associated with higher response rates including the response after pseudoprogression (vs. < 50%; 37.5% vs. 6.5%; p=0.049). Conclusion Pembrolizumab showed modest anti-tumor activity in heavily pretreated PD-L1--positive BTC patients. In patients who showed objective response, durable response could be achieved. [ABSTRACT FROM AUTHOR]

Purpose Since the introduction of nab-paclitaxel plus gemcitabine (nab-P+GEM) as first-line (1L) treatment for metastatic pancreatic adenocarcinoma (mPDAC), optimal second-line (2L) chemotherapy after progression is unclear. We assessed clinical outcomes of 2L chemotherapy for disease that progressed on 1L nab-P+GEM. Materials and Methods Among the 203 patients previously treated with 1L nab-P+GEM for mPDAC at Asan Medical Center, between February and December 2016, records of 120 patients receiving 2L chemotherapy after progression on nab-P+GEM were retrospectively reviewed. The response rate and survival were evaluated along with analysis of prognostic factors. Results Fluoropyrimidine-oxaliplatin doublets (FOLFOX or XELOX) were used in 78 patients (65.0%), fluoropyrimidine monotherapy in 37 (30.8%), and liposomal irinotecan plus fluorouracil in two (1.7%). The median progression-free survival (PFS) and overall survival (OS) were 3.29 months and 7.33 months from the start of 2L therapy. Fluoropyrimidine-oxaliplatin regimens and fluoropyrimidine monotherapy did not yield significantly different median PFS (2.89 months vs. 3.81 months, p=0.40) or OS (7.04 months vs. 7.43 months, p=0.86). A high neutrophil-lymphocyte ratio (> 2.2) and a short time to progression with 1L nab-P+GEM (< 6.4 months) were independent prognostic factors of poor OS with 2L therapy. Conclusion 2L fluoropyrimidine-oxaliplatin doublets and fluoropyrimidine monotherapy after failure of 1L nab-P+GEM had modest efficacy, with no differences in treatment outcomes between them. Further investigation is warranted for the optimal 2L chemo-regimens and sequencing of systemic chemotherapy for patients with mPDAC. [ABSTRACT FROM AUTHOR]

Purpose We previously demonstrated that CD44v9 and Ki-67 played an important role in predicting poor prognosis of early gastric cancer (EGC). However, little is known about combined use of both biomarkers as prognostic biomarker. The present study was performed to investigate the significance of CD44v9 and Ki-67 expression as a combination biomarker for EGC. Materials and Methods With tissue microarray for 158 EGC tissues, we performed immunohistochemical staining for CD44v9 and Ki-67. The whole patients were divided into three groups (group A, CD44v9-negative/Ki-67–low; group B, neither group A or C; and group C, CD44v9-positive/Ki-67–high). Its clinical significance was re-analyzed with adjustment via propensity score matching (PSM). For validation, we performed bootstrap resampling. Results The median follow-up duration was 90.4 months (range, 3.7 to 120.4 months). In the comparison according to CD44v9/Ki-67 expression, the combined use of the two biomarker clearly separated the three groups by 5-year survival rates (5-YSR, 96.3%, 89.8%, and 76.8% in group A, B, and C, respectively; p=0.009). After PSM, 5-YSR were 97.7% and 76.8% in group A+B and group C, respectively (p=0.002). Multivariable analysis demonstrated that group C had independently poor prognosis (hazard ratio, 9.137; 95% confidence interval, 1.187 to 70.366; p=0.034) compared with group A. Bootstrap resampling internally validated this result (p=0.016). Conclusion This study suggests that both positive CD44v9 and high Ki-67 expression are associated with poor prognosis in EGC, and the combined use of these markers provides better prognostic stratification than the single use of them. [ABSTRACT FROM AUTHOR]

Purpose Gemcitabine plus cisplatin (GemCis) is the standard first-line chemotherapy for patients with advanced biliary tract cancer (BTC). In ABC-02 study, the BTC patients received up to 6-8 cycles of 3-weekly GemCis; however, those without progression often receive more than 6-8 cycles. The clinical benefit of maintenance treatment in patients without progression is uncertain. Materials and Methods Advanced BTC patients treated with GemCis between April 2010 and February 2015 at Asan Medical Center, Seoul, Korea, were retrospectively analysed. The patients without progression after 6-8 cycles were stratified according to further treatment i.e., with or without further cycles of GemCis (maintenance vs. observation groups). The primary endpoint was overall survival (OS) and progression-free survival (PFS). Results Among the 740 BTC patients in the initial screen, 231 cases (31.2%) were eligible for analysis (111 in the observation group, 120 in the maintenance group). The median OS from the GemCis initiation was 20.5 months (95% confidence interval [CI], 15.4 to 25.6) and 22.4 months (95% CI, 17.0 to 27.8) in the observation and maintenance groups, respectively (p=0.162). The median PFS was 10.4 months (95% CI, 7.0 to 13.8) and 13.2 months (95% CI, 11.3 to 15.2), respectively (p=0.320). Conclusion GemCis maintenance is not associated with an improved survival outcome. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this study was to investigate the efficacy of stereotactic body radiation therapy (SBRT) as a tumor-associated antigen (TAA) presentation method for dendritic cell (DC) sensitization and evaluate its effect in combination with immunotherapy using an intratumoral injection of immature DCs (iDCs). Materials and Methods CT-26 colon carcinoma cell was used as a cancer cell line. Annexin V staining and phagocytosis assays were performed to determine the appropriate radiation dose and incubation time to generate TAAs. BALB/c mice were used for in vivo experiments. Cancer cells were injected into the right legs and left flanks to generate primary and metastatic tumors, respectively. The mice were subjected to radiation therapy (RT) alone, intradermal injection of electroporated DCs alone, or RT in combination with iDC intratumoral injection (RT/iDC). Tumor growth measurement and survival rate analysis were performed. Enzyme-linked immunospot and cytotoxicity assays were performed to observe the effect of different treatments on the immune system. Results Annexin V staining and phagocytosis assays showed that 15 Gy radiation dose and 48 hours of incubation was appropriate for subsequent experiments. Maximum DC sensitization and T-cell stimulation was observed with RT as compared to other TAA preparation methods. In vivo assays revealed statistically significant delay in the growth of both primary and metastatic tumors in the RT/iDC group. The overall survival rate was the highest in the RT/iDC group. Conclusion The combination of SBRT and iDC vaccination may enhance treatment effects. Clinical trials and further studies are warranted in the future. [ABSTRACT FROM AUTHOR]

Purpose Although gemcitabine plus cisplatin has been established as the standard first-line chemotherapy for patients with advanced biliary tract cancer (BTC), overall prognosis remains poor. We investigated the efficacy of a novel triplet combination of oxaliplatin, irinotecan, and S-1 (OIS) for advanced BTC. Materials and Methods Chemotherapy-naive patients with histologically documented unresectable or metastatic BTC were eligible for this multicenter, single-arm phase II study. Patients received 65 mg/m2 oxaliplatin (day 1), 135 mg/m2 irinotecan (day 1), and 40 mg/m2 S-1 (twice a day, days 1-7) every 2 weeks. Primary endpoint was objective response rate. Targeted exome sequencing for biomarker analysis was performed using archival tissue. Results In total, 32 patients were enrolled between October 2015 and June 2016. Median age was 64 years (range, 40 to 76 years), with 24 (75%) male patients; 97% patients had metastatic or recurrent disease. Response rate was 50%, and median progression-free survival and overall survival (OS) were 6.8 months (95% confidence interval [CI], 4.8 to 8.8) and 12.5 months (95% CI, 7.0 to 18.0), respectively. The most common grade 3-4 adverse events were neutropenia (32%), diarrhea (6%), and peripheral neuropathy (6%). TP53 and KRAS mutations were the most frequent genomic alterations (42% and 32%, respectively), and KRAS mutations showed a marginal relationship with worse OS (p=0.07). Conclusion OIS combination chemotherapy was feasible and associated with favorable efficacy outcomes as a first-line treatment in patients with advanced BTC. Randomized studies are needed to compare OIS with gemcitabine plus cisplatin. [ABSTRACT FROM AUTHOR]

Purpose: The present study is to investigate the significance of CD44 variant 9 (CD44v9) expression as a biomarker in primary gastric cancer. Materials and Methods: With various gastric tissues, we performed immunohistochemical staining for CD44v9. Results: The positive expression rates for CD44v9 in tumor, including adenoma, early gastric cancer (EGC), and advanced gastric cancer (AGC), were higher than those in non-tumor tissues (p=0.003). In addition, the higher expression for CD44v9 was observed as the tissue becomes malignant. In the analysis of 333 gastric cancer tissues, we found that positive expression rates for CD44v9 were higher in the intestinal type or well differentiated gastric cancer than in the diffuse type or poorly differentiated gastric cancer. Interestingly, the positive expression indicated poor prognosis in EGC (5-year survival rate [5-YSR] in stage I, 81.7% vs. 95.2%; p=0.013), but not in AGC (5-YSR in stage II, 66.9% vs. 62.2%; p=0.821; 5-YSR in stage III, 34.5% vs. 32.0%; p=0.929). Moreover, strong positive expression (3+) showed a trend suggesting worse prognosis only in EGC, and it appeared to be associated with lymph node metastasis. Conclusion: This study suggests that CD44v9 may be a good biomarker for prognosis prediction and for chemoprevention or biomarker-driven therapies only for EGC. [ABSTRACT FROM AUTHOR]