Abstract In clinical settings, patients receiving immune checkpoint inhibitors (ICIs) have different treatment criteria from those enrolled in clinical trials. There are concerns regarding the efficacy of ICIs in older adults due to the age-associated decline in the immune system, and no study has directly compared the efficacy of different ICIs in a real-world setting. We aimed to analyze ICIs use and treatment outcomes in Korean veterans with stage IV non-small-cell lung cancer (NSCLC). In total, 180 patients diagnosed with stage IV NSCLC between 2016 and 2021 were included in this analysis. Three cohort groups were derived based on ICI type (pembrolizumab, nivolumab, and atezolizumab treatment groups), and their clinical characteristics and survival outcomes were compared. The predictors of survival outcomes in patients with NSCLC were investigated using a Cox regression model. The objective response rate (ORR) was 22.4%, 8.2%, and 4.3% in the pembrolizumab, nivolumab, and atezolizumab groups, respectively, whereas the disease control rate (DCR) was 59.2, 55.7%, and 30.0%, respectively. There was no difference in the overall survival (OS) rate among the groups, and no treatment-specific OS benefit was observed relative to tumor PD-L1 expression, and bone metastasis was a poor prognostic factor for OS. Pembrolizumab and nivolumab were associated with a significant increase in ORR and DCR compared with atezolizumab, and there was no statistically significant difference in survival outcomes among the three ICIs, demonstrating that they may be an appropriate treatment option for older patients.

Histiocytic sarcoma (HS) is an extremely rare and aggressive malignant neoplasm of hematopoietic origin that shows morphologic and immunophenotypic evidence of histiocytic differentiation. In approximately 25% of the cases, presumed transdifferentiation of a preexisting hematolymphoid disorder can be demonstrated. Various extranodal sites, particularly the gastrointestinal tract, soft tissue, skin, and spleen, can be involved. Enhanced CT and FDG PET/CT findings of extranodal histiocytic sarcoma have been barely reported. We present a case with extranodal HS originating in the small intestine after gastric large B-cell lymphoma, mistaken for prostate cancer metastasis in a 76-year-old man.

Supplementary Table 1. Best response to treatment among response-evaluable patients treated with RPIID (n = 43)

Purpose: To provide a comprehensive analysis of ICI usage and treatment outcomes in elderly Korean veterans with stage IV NSCLC. Methods: Patients diagnosed with stage IV NSCLC between 2016 and 2021 were included, and three cohorts were derived according to the type of ICI received. Thereafter, the clinical characteristics and survival outcomes were compared. Results: Of the 180 patients with NSCLC (median age, 76 years) included in this study, 49 (27.7%), 61 (33.9%), and 70 (38.9%) received pembrolizumab, nivolumab, and atezolizumab, respectively, and 19.4%, 36.1%, and 34.4% had PD-L1 expressions < 1%, 1–49%, and ≥50%, respectively. The pembrolizumab, nivolumab, and atezolizumab groups, the objective response rates (ORR), and the disease control rates (DCR) were 22.4%, 8.2%, and 4.3% (p = 0.004), and 59.2, 55.7%, and 30.0% (p = 0.001), respectively. However, no difference in the overall survival (OS) rate was noted among the groups (12.6 months vs. 8.4 months vs. 7.7 months, p = 0.334). Similarly, there was no treatment specific OS benefit with respect to the tumor PD-L1 expression status. Interestingly, multivariate analysis identified bone metastasis as a significant poor prognostic factor for OS (HR = 2.75 [95% CI, 1.31–5.76], p = 0.007). Conclusion: Pembrolizumab and nivolumab showed stronger associations with increases in ORR and DCR than atezolizumab, but no statistically significant differences were observed with respect to OS.

Introduction: Thymic epithelial tumors (TETs) are rare but are the most common tumors of the anterior mediastinum. Platinum-based combination chemotherapy is the standard of care for such tumors and is associated with a 50% to 90% objective response rate (ORR) in metastatic disease. Nevertheless, there is no standard chemotherapeutic option after failure of platinum-based combination chemotherapy. Genetic alterations associated with the cell cycle, including pRB, p16INK4A, and cyclin D1, are most often observed in TETs. On the basis of these results, we conducted a phase 2 trial to evaluate the efficacy and safety of palbociclib in patients with recurrent or refractory advanced TETs.Methods: This is a phase 2, multicenter, open-label, single -arm study of palbociclib monotherapy in patients with recurrent or metastatic advanced TETs who failed one or more cytotoxic chemotherapies. The patients received 125 mg of oral palbociclib daily for 21 days, followed by a 7-day break. The primary end point was progression-free survival (PFS). The secondary end points were ORR, duration of response, overall survival, and safety.Results: Between August 2017 and October 2019, a total of 48 patients were enrolled. The median number of previous chemotherapies was one (range: one to four), and 21 (43.7%) of 48 patients received thymectomy. By the WHO classification, the patients were type A (n = 1), type B1 (n = 2), type B2 (n = 8), type B3 (n = 13), thymic carcinoma (n = 23), and unknown (n = 1). With a median follow-up of 14.5 months (range: 0.8-38.2), the median number of cycles of palbociclib monotherapy was 10 (range: 1-40). The ORR was 12.5% (four partial responses in thymoma and two partial responses in thymic carcinoma). The PFS at 6 months was 60.2%, and the median PFS was 11.0 months (95% confidence interval: 4.6-17.4). The median overall survival was 26.4 months (95% confidence interval: 17.4-35.4). The most common treatment-related adverse events of any grade were neutropenia (62.5%), anemia (37.5%), and thrombocytopenia (29.1%), and the most common grade 3/4 treatment-related hematologic adverse event was neutropenia (41.7%). Neutropenia above grade 3 was reversible, and there were no cases with neutropenic fever.Conclusions: Palbociclib monotherapy was well tolerated and had encouraging efficacy in patients with TETs who failed platinum-based combination chemotherapy.(c) 2022 Published by Elsevier Inc. on behalf of International Association for the Study of Lung Cancer.

Chronic neutrophilic leukemia (CNL) is a rare, potentially aggressive, myeloproliferative neoplasm. To the best of our knowledge, there are no previous reports dealing with 18F-FDG PET findings in CNL. We describe a case of CNL in a 69-year-old male, imaged with 18F-FDG PET/CT at diagnosis and during treatment.

Decitabine is widely accepted as the treatment options for elderly acute myeloid leukemia (AML) patients. However, the efficacy has yet been assessed in Asian population. We retrospectively analyzed the outcomes of 80 Korean elderly AML patients who were treated with decitabine. The median age was 74 years (range, 64 to 86 years) and 6 (7.5%), 48 (60.0%), and 25 (31.3%) patients were categorized to favorable, intermediate, and poor risk group, respectively. The median OS was 10.2 months (95% CI 5.0-15.4). Given that decitabine treatment demonstrated improved clinical outcomes, it could be considered as one of the first-line treatment for Korean elderly AML patients.

PURPOSE:Limited treatment options exist for patients with thymic epithelial tumor (TET) whose disease progresses after platinum-based chemotherapy. We conducted a phase II study of pembrolizumab in patients with TET to evaluate its efficacy and safety. METHODS:Patients with histologically confirmed TET whose disease progressed after at least one line of platinum-based chemotherapy were eligible for the study. Patients were excluded if they had an active autoimmune disease requiring systemic treatment within the past year or documented history of clinically severe autoimmune disease. Patients received 200 mg of pembrolizumab intravenously every 3 weeks until tumor progression or unacceptable toxicity. The primary objective of response rate was assessed every 9 weeks by investigators. RESULTS:Of 33 patients enrolled, 26 had thymic carcinoma and seven had thymoma. Of seven thymoma, two (28.6%; 95% CI, 8.2% to 64.1%) had partial response, and five (71.6%) had stable disease. Of 26 thymic carcinoma, five (19.2%; 95% CI, 8.5% to 37.9%) had partial response and 14 (53.8%) had stable disease. The median progression-free survival was 6.1 months for both groups. The most common adverse events of any grade included dyspnea (11; 33.3%), chest wall pain (10; 30.3%), anorexia (seven; 21.2%), and fatigue (seven; 21.2%). Five (71.4%) of seven patients with thymoma and four (15.4%) of 26 patients with thymic carcinoma reported grade ≥ 3 immune-related adverse events, including hepatitis (four; 12.1%), myocarditis (three; 9.1%), myasthenia gravis (two; 6.1%), thyroiditis (one; 3.0%), antineutrophil cytoplasmic antibody-associated rapidly progressive glomerulonephritis (one; 3.0%), colitis (one; 3.0%), and subacute myoclonus (one; 3.0%). CONCLUSIONS:Pembrolizumab showed encouraging antitumor activity in patients with advanced TET. Given the high incidence of autoimmunity, additional studies are needed to identify those who can benefit from pembrolizumab without immune-related adverse events.

Background/Aims Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy that typically presents in the form of skin manifestations with or without lymph node and bone marrow involvement. Given its rarity and recent recognition as a distinct pathological entity, no standard of treatment exists for this aggressive disease and its prognosis is particularly dismal. Methods We retrospectively analyzed clinical features and treatment outcomes of patients who were diagnosed with BPDCN between 2000 and 2014. Results Ten patients had a median age at diagnosis of 41 years (range, 18 to 79), and seven patients were male. Sites of disease involvement were the skin (n = 7), lymph node (n = 5), bone marrow (n = 2), liver (n = 2), spleen (n = 2), and soft tissue (n = 1). Intensified chemotherapy regimens such as hyperCVAD regimen (cyclophosphamide, vincristine, doxorubicin, dexamethasone, methotrexate, cytarabine), and VPDL (vincristine, methylprednisolone, daunorubicin, L-asparaginase) were used as a first-line treatment. Although all patients treated with intensified chemotherapy showed an objective response (five patients with complete response) with median progression-free survival of 11.2 months (range 6.2 to 19.4), complete remission was not sustained for more than 2 years in any case. The response was relatively long-lived compared with previously reported CHOP (doxorubicin, cyclophosphamide, vincristine, prednisone)-like regimens, but the above regimens do not result in long-term remission. Conclusions All patients treated with hyperCVAD or VPDL showed an objective response, but the duration of response was relatively short. Thus, the development of more effective induction as well as consolidation treatment strategy should be warranted to improve this rare disease entity.

The macrophage inflammatory protein 1α (MIP‐1α) is anticipated to have a role in extranodal natural killer (NK)/T‐cell lymphoma (ENKTL) because the expression of MIP‐1α is related to Epstein–Barr virus (EBV) latency in EBV‐related non‐Hodgkin lymphoma cells. Thus, we measured the serum level of MIP‐1α in 69 patients with ENKTL using frozen serum samples that were archived at diagnosis. As serum level of MIP‐1α was not detectable in 19 patients (range: 0–24.37 pg/mL), patients were dichotomized into positive (n = 50) and negative (n = 19) MIP‐1α groups according to the presence of detectable level of MIP‐1α in serum. MIP‐1α‐positive group showed a significantly poor overall survival (OS) in comparison with the MIP‐1α‐negative group (p = 0.004). In the subgroup analysis, the positivity of MIP‐1α was significantly associated with OS in patients with stage IIIE/IV and a detectable level of EBV DNA (p = 0.002 and 0.032, respectively). Multivariate analysis also showed that the positivity of MIP‐1α was independently associated with worse OS together with bone marrow involvement (p = 0.002). An in vitro study with patient‐derived ENKTL tumour cells showed the expression of CCR1 and CCR5 on the surface of tumour cells (28% and 14%, respectively) , and the addition of MIP‐1α to the culture media of tumour cells increased cell growth supporting the negative impact of MIP‐1α on the prognosis of ENKTL patients. In conclusion, serum levels of MIP‐1α could predict survival outcomes in patients with ENKTL. Therefore, MIP‐1α should be considered for prognostication and a potential therapeutic target. Copyright © 2016 John Wiley & Sons, Ltd.

The aim of this retrospective study was to evaluate the clinical outcomes of reduced dose, biweekly docetaxel chemotherapy for Korean patients with castrate-resistant prostate cancer (CRPC).

The role of EGFR tyrosine-kinase inhibitors in the second-line for patients with squamous non-small-cell lung cancer (NSCLC) remains unclear. We conducted a prospective phase II study to assess use of gefitinib in patients with squamous NSCLC as second-line chemotherapy, and investigated the predictive and prognostic value of a proteomic signature using VeriStrat test. Between December 2011 and October 2015, 56 patients with histologically confirmed, second-line, Stage IIIB or IV NSCLC were enrolled in 9 centers in Republic of Korea. Patients were treated with gefitinib (250 mg per day orally). The proteomic test classification was masked for patients and investigators. The primary end point was disease control rate (DCR) at 8-weeks, and the secondary end points included toxicity, progression-free survival (PFS), overall survival (OS), and correlation between the serum proteomic test classification and treatment. This study is registered with ClinicalTrials.gov, number NCT01485809. The median age was 69 years (range, 41-83) and 55 (98%) patients were male, and 49 (88%) had an ECOG PS of 1. Fifty five (98%) of patients had received platinum-based chemotherapy. The DCR at 8 weeks was 50.0% (95% confidence interval [CI] 34.8-63.4). With a median follow-up of 5.5 months, the median PFS and OS were 2.8 (95% CI 1.3-4.3) and 6.4 (5.4-7.4) months, respectively. The most common adverse event were rash (16 [29%]) and diarrhea (14 [25%]). Pretreatment plasma was available for 50 samples, and VeriStrat testing was successful in 45 samples (90%) with 71% classified as Good. The median PFS were 3.2 (95% CI 1.9-4.7) and 2.4 (1.5-3.3) months for VeriStrat Good vs. Poor patients, respectively (p=0.639). The median OS of VeriStrat Good was longer than those of VeriStrat Poor (11.4 [5.7-17.0] vs 4.8 [2.5-7.0] months), which was not statistically significant (p=0.052). These data suggest that gefitinib is modest activity as second-line chemotherapy in patients with squamous NSCLC. Serum proteomic test using VeriStrat is not prognostic for both OS and PFS among squamous NSCLC patients treated with gefitinib.

e638 Background: The aim of this retrospective study was to evaluate clinical outcomes of biweekly 40 mg/m2 docetaxel plus prednisolone, as compared with standard 3-weekly regimen in Korean patients with castration-resistant prostate cancer (CRPC). Methods: We retrospectively reviewed the medical records of 48 patients with metastatic CRPC who were consecutively treated with docetaxel plus prednisolone as first-line chemotherapy between Jan 2012 and Dec 2014 at Samsung Medical Center (Seoul, Korea). Prior to the adoption of a biweekly regimen in Oct 2013, our institutional standard chemotherapy was docetaxel 75 mg/m2 every 3 weeks for patients with CRPC (n = 24). After Oct 2013, all chemotherapy-naïve CRPC patients received 40 mg/m2 biweekly regimen (n = 24). The primary end point was the PSA response, defined as a greater than 50% decline in PSA levels from baseline. Results: The baseline characteristics of the patients were similar in the two treatment groups. The most common cause of treatment discontinuation was disease progression: 17 (71%) in 3-weekly group and 20 (82%) in biweekly group. PSA responses were observed in 12 (50%) and 11 (46%) patients in the 3-weekly and biweekly groups, respectively. Time-to-failure (TTF, 4.5 versus 3.9 months) and time-to-progression (TTP, 5.0 versus 4.2 months) were statistically similar between the 3-weekly and biweekly groups, respectively. In 3-weekly group, the most commonly observed toxic effects were anemia and neutropenia. Whereas, in biweekly group, fatigue and nail changes were the most commonly observed toxic effects. Conclusions: Within the limitation of a retrospective study, biweekly reduced dose docetaxel regimen is active and well-tolerated in Korean patients with metastatic CRPC.

Monocarboxylate transporters (MCTs) play a major role in up-regulation of glycolysis and adaptation to acidosis. However, the role of MCTs in gastric cancer (GC) is not fully understood. We investigated the potential utilization of a new cancer therapy for GC. We characterized the expression patterns of the MCT isoforms 1, 2, and 4 and investigated the role of MCT in GC through in vitro and in vivo tests using siRNA targeting MCTs. In GC cell lines, MCT1, 2, and 4 were up-regulated with different expression levels; MCT1 and MCT4 were more widely expressed in GC cell lines compared with MCT2. Inhibition of MCTs by siRNA or AR-C155858 reduced cell viability and lactate uptake in GC cell lines. The effect of inhibition of MCTs on tumor growth was also confirmed in xenograft models. Furthermore, MCT inhibition in GC cells increased the sensitivity of cells to radiotherapy or chemotherapy. Compared with normal gastric tissue, no significant alterations of expression levels in tumors were identified for MCT1 and MCT2, whereas a significant increase in MCT4 expression was observed. Most importantly, MCT4 was highly overexpressed in malignant cells of acsites and its silencing resulted in reduced tumor cell proliferation and lactate uptake in malignant ascites. Our study suggests that MCT4 is a clinically relevant target in GC with peritoneal carcinomatosis.

PurposePapillary thyroid carcinomas (PTCs) frequently involve genetic alterations. The objective of this study was to investigate genetic alterations and further explore the relationships between these genetic alterations and clinicopathological characteristics in a high-recurrence risk (node positive, N1) PTC group.Materials and MethodsTumor tissue blocks were obtained from 240 surgically resected patients with histologically confirmed stage III/IV (pT3/4 or N1) PTCs. We screened gene fusions using NanoString's nCounter technology and mutational analysis was performed by direct DNA sequencing. Data describing the clinicopathological characteristics and clinical courses were retrospectively collected.ResultsOf the 240 PTC patients, 207 (86.3%) had at least one genetic alteration, including BRAF mutation in 190 patients (79.2%), PIK3CAmutation in 25 patients (10.4%), NTRK1/3 fusion in six patients (2.5%), and RET fusion in 24 patients (10.0%). Concomitant presence of more than two genetic alterations was seen in 36 patients (15%). PTCs harboring BRAF mutation were associated with RET wild-type expression (p=0.001). RET fusion genes have been found to occur with significantly higher frequency in N1b stage patients (p=0.003) or groups of patients aged 45 years or older (p=0.031); however, no significant correlation was found between other genetic alterations. There was no trend toward favorable recurrence-free survival or overall survival among patients lacking genetic alterations.ConclusionIn the selected high-recurrence risk PTC group, most patients had more than one genetic alteration. However, these known alterations could not entirely account for clinicopathological features of high-recurrence risk PTC.

BACKGROUND:Metastatic breast cancer (MBC) remains a devastating and incurable disease. Over the past decade, the implementation of clinical trials both with and without molecular targeted therapeutics has impacted the daily clinical treatment of patients with MBC. In this study, we determine whether including MBC patients in clinical trials affects clinical outcomes.METHODS:We retrospectively reviewed data for a total of 863 patients diagnosed with initial or recurrent (after receiving adjuvant systemic treatments following surgery) metastatic disease between January 2000 and December 2013. Data were obtained from the breast cancer database of Samsung Medical Center.RESULTS:Among the 806 patients selected for inclusion, 188 (23%) had participated in clinical trials. A total of 185 clinical trials were conducted from 2000 to 2014. When compared with earlier periods (n = 10 for 2000-2004), clinical trial enrollment significantly increased over time (n = 103 for 2005-2009, P = 0.024; n = 110 for 2010-2014, P = 0.046). Multivariate analyses revealed that biologic subtype, distant recurrence free interval (DRFI), and clinical trial enrollment were independent predictors of overall survival. Patients who participated in clinical trials showed improved survival, with a hazard ratio of 0.75 (95% CI, 0.59-0.95), which was associated with a 25% reduction in the risk of death. However, subgroup analysis showed that this improved survival benefit was not maintained in patients with triple negative breast cancer (TNBC).CONCLUSIONS:Although not conclusive, we could speculate that there were differences in the use of newer agents or regimens over time, and these differences appear to be associated with improved survival.

The purpose of this study was to investigate the clinicopathologic features and prognostic factors affecting outcome in patients with isolated locoregional recurrence of breast cancer (ILRR).We retrospectively analyzed the medical records of 104 patients who were diagnosed with ILRR and underwent curative surgery from January 2000 to December 2010 at Samsung Medical Center.Among 104 patients, 43 (41%) underwent total mastectomy and 61 (59%) underwent breast-conserving surgery for primary breast cancer. The median time from initial operation to ILRR was 35.7 months (4.5-132.3 months). After diagnosis of ILRR, 45 (43%) patients were treated with mastectomy, 41 (39%) with excision of recurred lesion, and 18 (17%) with node dissection. During a median follow-up of 8.9 years, the 5-year overall survival was 77% and 5-year distant metastasis-free survival (DMFS) was 54%. On multivariate analysis, younger age (< 35 years), higher stage, early onset of elapse (≤ 24 months), lymph node recurrences, and subtype of triple negative breast cancer (TNBC) were found to be independently associated with DMFS. Patients in the no chemotherapy group showed a longer DMFS after surgery for ILRR than those treated with chemotherapy (median 101.5 vs. 48.0 months, p = 0.072) but without statistical significance.Our analysis showed that younger age (< 35 years), higher stage, early onset of relapse (≤ 24 months), lymph node recurrence, and subtype of TNBC are the worst prognostic factors for ILRR.

Objective: Disease-related weight loss is relatively common in patients with newly diagnosed multiple myeloma (MM), but limited data exist regarding the effects of nutritional status on survival. The aim of this study was to assess the relationship between malnutrition (as measured by Patient-Generated Subjective Global Assessment [PG-SGA]) and clinical characteristics of patients with MM, and to investigate the association between the PG-SGA score before chemotherapy and overall survival in MM patients.Methods: Using the PG-SGA score, we retrospectively explored the effect of malnutrition on the survival of Asian patients with MM.Results: We divided 216 patients with MM into three groups based on their PG-SGA scores. Of these patients 23% (n = 50) had PG-SGA scores >= 9, indicating severe malnutrition requiring specialist nutrition intervention. Body mass index and serum hemoglobin were independently associated with PG-SGA scores (P < 0.05). The median survival time was not reached in nourished patients with PGSGA scores of 0 to 3, 58.7 mo in moderately malnourished patients with PG-SGA scores of 4 to 8, and 35 mo in severely malnourished patients with PG-SGA scores >= 9 (P = 0.001). Multivariate analysis revealed that PG-SGA scores >= 9 compared with PG-SGA scores of 0 to 3 (hazard ratio [HR], 2.347; 95% confidence interval [CI], 1.271-4.334; P = 0.006), International Staging System (155) stage III compared with ISS stage I (HR, 2360; 95% CI, 1.271-4.379; P = 0.007), and autologous stem cell transplantation (HR, 0388; 95% CI, 0.248-0.606; P < 0.001) were associated with overall survival.Conclusions: A higher PG-SGA score before chemotherapy was associated with reduced survival among patients with MM. Nutritional evaluation should be an integral part of the clinical assessment of MM patients, and the PG-SGA score would be an appropriate tool to evaluate nutritional status. (C) 2016 Elsevier Inc. All rights reserved.

Abstract Purpose: In this phase Ib/II study, we aimed to assess the safety and efficacy of afatinib plus nimotuzumab (N) in advanced non–small cell lung cancer (NSCLC) patients with acquired resistance to gefitinib or erlotinib. Experimental Design: In phase Ib stage, patients received afatinib (40 mg or 30 mg once daily) plus nimotuzumab (100 mg or 200 mg once weekly) for 28-day cycles to determine the recommended phase II dose (RPIID). The safety and efficacy of RPIID dose was evaluated in phase II stage. Results: In total, 50 patients were enrolled (13 to phase Ib and 37 to phase II). In the first dose-finding cohort (afatinib 40 mg plus nimotuzumab 100 mg), one patient experienced dose-limiting toxicity (DLT) of grade 3 diarrhea and in the subsequent cohort (afatinib 40 mg plus nimotuzumab 200 mg), two DLTs (grade 3 diarrhea and grade 3 neutropenia) occurred in 2 of 6 patients. Accordingly, RPIID was determined as afatinib 40 mg plus nimotuzumab 100 mg. In 44 patients treated with RPIID, 7 (16%) patients had grade 3 toxicities; skin rash (7%), diarrhea (5%), acne (2%), and fatigue (2%). The overall response rate was 23% and the median duration of response was 4.3 months (range, 0.7–16.2 months). The median progression-free survival and overall survival were 4.0 months [95% confidence interval (CI), 2.3–5.7 months] and 11.7 months (95% CI, 9.4–14.0 months), respectively. Conclusions: Combination treatment of afatinib and nimotuzumab demonstrated an acceptable safety profile and encouraging antitumor activity in advanced NSCLC patients with acquired resistance to gefitinib or erlotinib. Larger phase III trial is warranted to confirm its efficacy and safety. Clin Cancer Res; 22(9); 2139–45. ©2015 AACR.

OBJECTIVE:We conducted this study to investigate the value of early metabolic responses assessed by (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in predicting prognosis and monitoring treatment response in patients with unresectable thymic epithelial tumors (TETs).PATIENTS AND METHODS:Study subjects were selected from the prospective dataset of a phase II clinical trial for cisplatin plus Cremorphor EL-free paclitaxel. A total of thirty patients with unresectable TETs who underwent baseline and early post treatment scan after two cycles of chemotherapy were enrolled (22 Male; mean age 55.0±15.0years). Metabolic parameters including metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of the tumor lesions were measured.RESULTS:Multivariate analysis using Cox proportional hazards regression model showed that percent decrease of MTV (HR=0.995 by 1% decrease, P=0.037) and TLG (HR=0.996 by 1% decrease, P=0.044) were significant predictors of progression-free survival (PFS). Receiver operating characteristic curve identified an 88.0% decrease in MTV and a 92.0% decrease in TLG as the optimal cut-off value for disease progression. Responders with ≥88% of ΔMTV and ≥92% of Δ TLG had significantly longer PFS than non-responders (P=0.012, 0.026, respectively).CONCLUSION:The percent decrease in MTV and TLG of tumor lesions measured by early post treatment FDG PET/CT significantly associated with disease progression in this study. Early metabolic response based on these volumetric parameters has the potential to monitor treatment response and predict prognosis in patients with unresectable TETs.