Choong Kun Lee

Cumulative Metformin Use and Its Impact on Survival in Gastric Cancer Patients After Gastrectomy.

OBJECTIVE The aim of this study was to evaluate the association between metformin and survival of gastric cancer (GC) patients. BACKGROUND Metformin has recently received attention as a potential anticancer treatment. However, no study has shown the survival benefit of metformin for GC patients. METHODS A total of 1974 GC patients who underwent curative gastrectomy were compared for survival according to groups; 132 diabetic patients treated with metformin, 194 diabetic patients without metformin, and 1648 non-diabetic patients. RESULTS During the median follow-up period of 6.2 years (interquartile range, 4.7-7.8 years), 381 patients (19.3%) died, including 302 (15.3%) who died from GC. The non-diabetic patients had significantly better recurrence-free survival (RFS; P < 0.0001), cancer-specific survival (CSS; P = 0.006), and overall survival (OS; P < 0.0001). However, the diabetic patients treated with metformin had a significantly better prognosis than those who were not (OS: hazard ratio [HR] = 0.584, 95% confidence interval [CI], 0.369-0.926; CSS: HR = 0.57, 95% CI, 0.334-0.975; RFS: HR = 0.633, 95% CI, 0.410-0.977), and metformin treatment prolonged survival in diabetic patients to a rate comparable to that in non-diabetic patients. In multivariable analysis using the Cox proportional hazard model with time-dependent covariates, each cumulative 6 months of metformin use was significantly associated with a decreased risk of recurrence, cancer-specific mortality, and all-cause mortality (RFS: HR = 0.864, 95% CI, 0.797-0.937; CSS: HR = 0.865, 95% CI, 0.782-0.958; OS: HR 0.870, 95% CI, 0.801-0.945). CONCLUSIONS The increased cumulative duration of metformin use decreased the recurrence, all-cause mortality, and cancer-specific mortality rates among GC patients with diabetes who underwent gastrectomy.

Comparison of various subjective video quality assessment methods

In this paper, we present comparison of three subjective testing methods: the double stimulus continuous quality scale (DSCQS) method, the single stimulus continuous quality evaluation (SSCQE) method and the absolute category rating (ACR) method. The DSCQS method was used for validate objective models in the VQEG Phase II FRTV test. The SSCQE method is chosen to be used in the VQEG RRTV test. The ACR method is chosen to be used in the VQEG Multimedia test. Since a different subjective test method is used in each test, analyses of the three methods will provide helpful information in understanding human perception of video quality.

Cardiotoxicity of trastuzumab in patients with HER2-positive gastric cancer

Trastuzumab-induced cardiotoxicity (TIC) is the primary adverse event that limits the use of trastuzumab in HER2-positive breast cancer patients. However, the incidence and risk factors of TIC in HER2-positive gastric cancer are not known. Therefore, we evaluated the incidence and predictive factors of TIC in gastric cancer patients treated with trastuzumab in clinical practice. We reviewed cardiac dysfunction in HER2-positive gastric cancer patients between December 2005 and April 2015 in a prospectively-collected database that included prospective clinical trials at Yonsei Cancer Center, Republic of Korea. TIC was defined as an absolute decline in left ventricular ejection fraction (LVEF) of at least 10 percentage points from the baseline to a value less than 55%, as identified by a multiple-gated acquisition scan or an echocardiogram. Among the 115 patients, 70 patients (60.9%) received trastuzumab combined with chemotherapy, and 45 patients (39.1%) received chemotherapy alone as a first-line therapy. Symptomatic heart failure was not observed in either group, but a significant asymptomatic drop in LVEF was noted in five (7.1%) of the trastuzumab combined-group patients and in one (2.2%) chemotherapy-only group patient [hazard ratio (HR), 3.47; 95% confidence interval (CI), 0.40–29.8; P=0.257]. TIC was observed more frequently in elderly patients than in younger patients (HR, per age in year, 1.16; 95% CI, 1.02–1.31; P=0.019). Similar to prior observations in breast cancer, TIC in gastric cancer patients is not frequent or reversible. However, the asymptomatic drop in LVEF should be monitored continually in HER2-positive gastric cancer patients treated with trastuzumab, especially in elderly patients.Trastuzumab-induced cardiotoxicity (TIC) is the primary adverse event that limits the use of trastuzumab in HER2-positive breast cancer patients. However, the incidence and risk factors of TIC in HER2-positive gastric cancer are not known. Therefore, we evaluated the incidence and predictive factors of TIC in gastric cancer patients treated with trastuzumab in clinical practice. We reviewed cardiac dysfunction in HER2-positive gastric cancer patients between December 2005 and April 2015 in a prospectively-collected database that included prospective clinical trials at Yonsei Cancer Center, Republic of Korea. TIC was defined as an absolute decline in left ventricular ejection fraction (LVEF) of at least 10 percentage points from the baseline to a value less than 55%, as identified by a multiple-gated acquisition scan or an echocardiogram. Among the 115 patients, 70 patients (60.9%) received trastuzumab combined with chemotherapy, and 45 patients (39.1%) received chemotherapy alone as a first-line therapy. Symptomatic heart failure was not observed in either group, but a significant asymptomatic drop in LVEF was noted in five (7.1%) of the trastuzumab combined-group patients and in one (2.2%) chemotherapy-only group patient [hazard ratio (HR), 3.47; 95% confidence interval (CI), 0.40-29.8; P=0.257]. TIC was observed more frequently in elderly patients than in younger patients (HR, per age in year, 1.16; 95% CI, 1.02-1.31; P=0.019). Similar to prior observations in breast cancer, TIC in gastric cancer patients is not frequent or reversible. However, the asymptomatic drop in LVEF should be monitored continually in HER2-positive gastric cancer patients treated with trastuzumab, especially in elderly patients.

Depth of response is a significant predictor for long-term outcome in advanced gastric cancer patients treated with trastuzumab

Purpose We aimed to determine and compare the predictive values of depth of response (DpR) and early tumor shrinkage (ETS) on long-term outcomes in gastric cancer patients treated with trastuzumab. Results From a total of 368 computed tomography examinations, DpR and ETS were evaluated. DpR was a significant tumor-size metric in predicting PFS and OS, and showed better discriminatory ability (higher Cτ indices, 0.6957 for PFS; 0.7191 for OS) than ETS. DpR ≥ 45% (vs. < 45%) was the optimal cutoff value, as it was best able to identify patients with longer PFS (median 9.0 vs. 6.3 months, hazard ratio [HR] = 0.608; 95% confidence interval [CI]: 0.335 to 1.104; P = 0.102) and OS (median 23.5 vs. 13.1 months, HR = 0.441; 95% CI: 0.203 to 0.955; P = 0.038). Materials and Methods Sixty-one gastric cancer patients who received first-line trastuzumab-based chemotherapy were assessed for DpR and ETS. We employed Kaplan-Meier estimates, log-rank tests, Cox proportional hazards regression models, time-dependent receiver operating characteristics, and Youdens J index to evaluate and determine cutoff values of DpR and ETS as predictors of progression-free survival (PFS) and overall survival (OS). Conclusions DpR and ETS were significant predictors of long-term outcomes in gastric cancer patients treated with first-line trastuzumab. Validation in prospective trials with larger patient populations is needed.

PTEN loss and level of HER2 amplification is associated with trastuzumab resistance and prognosis in HER2-positive gastric cancer

Background Trastuzumab is an active agent against human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC). This study aimed to characterize resistance to trastuzumab-based front-line chemotherapy in HER2+ GC patients and to establish factors predictive of this resistance. Results Among 129 HER2+ GC patients, 25% displayed rapid disease progression within 4 months from initiation of therapy. These patients showed a higher rate of signet ring cell histology, bone metastasis, poor performance status, frequent loss of PTEN expression, and low HER2 amplification index compared with patients who were progression-free for at least 4 months. In contrast, there was no significant difference in the frequency of the PIK3R1 variant. Multivariate analyses confirmed two independent molecular predictors for trastuzumab resistance: loss of PTEN expression and low HER2 amplification index (<5). Patients with one or both molecular predictors at diagnosis exhibited worse progression-free and overall survival compared to those without risk factors (p < 0.001 and p = 0.001, respectively). Conclusion In HER2+ GC patients, loss of PTEN expression and low HER2 AI correlated with resistance to trastuzumab-based therapy and dismal prognosis. Since patients harboring these molecular predictors are unlikely to respond to trastuzumab-based therapy, other novel therapeutic targets needed to be considered. Methods HER2+ GC patients who were treated with trastuzumab in combination with either 5-fluorouracil/cisplatin or capecitabine/cisplatin were enrolled. Clinicopathologic features and molecular alterations of HER2, phosphoinositide 3-kinase regulatory subunit 1 (PIK3R1), and phosphatase and tensin homolog (PTEN) were correlated with treatment outcome. Factors predictive of resistance were also explored.

Multicentric Type 3 Gastric Neuroendocrine Tumors.

A 50-year-old woman with incidentally detected multiple gastric polyps and biopsy-proven neuroendocrine tumor (NET) was referred to our hospital. More than 10 polypoid lesions (less than 15 mm) with normal gastric mucosa were detected from the gastric body to the fundus. The serum level of gastrin was within the normal limits. There was no evidence of atrophic changes on endoscopy and serologic marker as pepsinogen I/II ratio. Computed tomography of the abdomen and pelvis revealed no evidence of metastatic lesions. She refused surgery, and we performed endoscopic polypectomy for almost all the gastric polyps that were greater than 5 mm. Although the histological examination revealed that all the removed polys were diagnosed as NET G1, three of them extended to the lateral or vertical resection margins, while two exhibited lymphovascular invasion. A follow-up upper endoscopy that was performed 6 months after the diagnosis showed multiple remnant gastric polyps that were suggestive of remnant gastric NET.

Results of a Phase II Study to Evaluate the Efficacy of Docetaxel and Carboplatin in Metastatic Malignant Melanoma Patients Who Failed First-Line Therapy Containing Dacarbazine

Purpose There is no standard second-line regimen for malignant melanoma patients with disease progression after first-line chemotherapy, and platinum-alkylating agents combined with paclitaxel have shown modest efficacy. Materials and Methods We conducted a phase II, open-label, single-arm study to test the efficacy of docetaxel combined with carboplatin for malignant melanoma patients who failed previous treatment with dacarbazine. Intravenous docetaxel (35 mg/m2 on days 1 and 8 of each cycle) and carboplatin (area under the curve 3 on days 1 and 8 of each cycle) was administered every 21 days. Primary end point was objective response rate (ORR). Results Thirty patients were enrolled in the study, and the median follow-up duration was 19.8 months. Among 25 per-protocol patients, there were three responders (1 with complete response and 2 with partial response) and 17 stable disease patients (ORR, 12.0%). Among the per-protocol population, the median progression-free survival (PFS) was 4.3 months and the median overall survival (OS) was 9.6 months. Uveal melanoma patients (n=9) showed the best prognosis compared to other subtypes (median PFS, 7.6 months; OS, 9.9 months). The most common grade 3 or 4 adverse event was neutropenia (n=15, 50.0%). Conclusion Docetaxel combined with carboplatin showed association with an acceptable safety profile and overall efficacy for patients with malignant melanoma who had progressed on chemotherapy containing dacarbazine.

A Prediction Model of Tumor Progression and Survival in HER2-Positive Metastatic Gastric Cancer Patients Treated with Trastuzumab and Chemotherapy

The effects of different patient factors and dose levels of chemotherapeutic agents on clinical outcomes in advanced gastric cancer are not as yet fully characterized. We aimed at developing an integrative model that incorporates dose and covariate information to predict tumor growth and patient survival in advanced gastric cancer patients treated with trastuzumab (T), 5-FU(F)/capecitabine (X) (F or X), and cisplatin (P). Sixty-nine patients (training dataset) were used for model building and a separate 86 patients (test dataset) for model validation. A fraction of tumor cells sensitive to each drug was incorporated as a model parameter, and T was assumed as cytostatic and X/F and P as cytotoxic. Cox proportional hazards analyses were performed on model parameters and patient covariates. The model well described the time course of observed tumor size changes, and revealed that the pretreatment tumor growth rate constant kg, which was formulated as a function of pretreatment disease duration and baseline tumor size, was positively correlated with baseline tumor size (p = 0.0084) and histologic grade (p = 0.034), and the efficacy of 5-FU with body weight (p < 2e−16) and that of cisplatin with histologic grade (p = 0.00013). Prior gastrectomy and Eastern Cooperative Oncology Group scores were significant prognostic factors for progression-free survival (PFS). For hazards analysis, a unit increase of kg was associated with a relative risk of 3.19 for PFS (p = 0.00055) and 4.45 for OS (p = 2e−04) in the test dataset, with a similar trend observed in the training dataset. Dose-response simulations showed that, for small baseline tumor size or low histologic grade, a maximum cytotoxic effect was attainable with a dose smaller than the current recommended dose.