• Journal of Gastric Cancer
• /
• v.22 no.1
• /
• pp.67-77
• /
• 2022

Purpose: Tegafur/gimeracil/oteracil (S-1) and capecitabine plus oxaliplatin (CAPOX) are standard adjuvant chemotherapies (ACs) administered after gastrectomy to patients with stage II or III gastric cancer. However, the efficacy of AC in elderly patients remains unclear. The objective of this retrospective multicenter cohort study was to compare the efficacies of S-1 and CAPOX AC in patients aged ≥70 years. Materials and Methods: Nine hundred eighty-three patients who were treated with AC using S-1 (768 patients) or CAPOX (215 patients) were enrolled in this study. Each patient underwent AC after curative gastrectomy for stage II or III gastric cancer at one of 27 hospitals in the Republic of Korea between January 2012 and December 2013. Relapse-free survival (RFS) and overall survival (OS) were analyzed according to AC regimen and age group. Results: Of the 983 patients, 254 (25.8%) were elderly. This group had a similar RFS (P=0.099) but significantly poorer OS (p=0.003) compared with the non-elderly group. Subgroup analysis of the non-elderly group revealed no AC-associated differences in survival. Subgroup analysis of the elderly group revealed significantly better survival in the S-1 group than in the CAPOX group (RFS, P<0.001; OS, P<0.001). Multivariate analysis revealed that the CAPOX regimen was an independent poor prognostic factor for RFS (hazard ratio [HR], 1.891; 95% confidence interval [CI], 1.072-3.333; P=0.028) and OS (HR, 2.970; 95% CI, 1.550-5.692; P=0.001). Conclusions: This multicenter observational cohort study found significant differences in RFS and OS between S-1 and CAPOX AC among patients with gastric cancer aged ≥70 years.

• The Bulletin of The Korean Astronomical Society
• /
• v.45 no.1
• /
• pp.34.3-34.3
• /
• 2020

Faint z ~ 5 quasars with M1450 ~ -23 mag are known to be the potentially important contributors to the ultraviolet ionizing background in the post-reionization era. However, their number density has not been well determined, making it difficult to assess their role in the early ionization of the intergalactic medium (IGM). In this work, we present the updated results of our z ~ 5 quasar survey using the Infrared Medium-deep Survey (IMS), a near-infrared imaging survey covering an area of 85 square degrees. From our spectroscopic observations with the Gemini Multi-Object Spectrograph (GMOS) on the Gemini-South 8 m Telescope, we discovered eight new quasars at z ~ 5 with -26.1 ≤ M1450 ≤ -23.3. Combining our IMS faint quasars with the brighter Sloan Digital Sky Survey (SDSS) quasars, we derive, for the first time, the z ~ 5 quasar luminosity function (QLF) without any fixed parameters down to the magnitude limit of M1450 = -23 mag. We find that the faint-end slope of the QLF is very flat (-1.2) with a characteristic luminosity of -25.7 mag. The number density of z ~ 5 quasars from the QLF gives lower ionizing emissivity and ionizing photon density than those in previous works. These results imply that quasars are responsible for only 10-20% of the photons required to completely ionize the IGM at z ~ 5, disfavoring the idea that quasars alone could have ionized the IGM at z ~ 5.

• Nuclear Medicine and Molecular Imaging
• /
• v.40 no.5
• /
• pp.263-270
• /
• 2006

Purpose: Several radioisotope-labeled thymidine derivatives such as $[^{11}C]$thymidine was developed to demonstrate cell proliferation in tumor. But it is difficult to track metabolism with $[^{11}C]$thymidine due to rapid in vivo degradation and its short physical half-life. 3'-$[^{18}F]$fluoro-3'-deoxythymidine ($[^{18}F]$FLT) was reported to have the longer half life of fluorine-18 and the lack of metabolic degradation in vivo. Here, we described the synthesis of the 3'-$[^{18}F]$fluoro-3'-deoxythymidine ($[^{18}F]$FLT) and compared with $([^{18}F]FET)\;and\;([^{18}F]FDG)$ in cultured 9L cell and obtained the biodistribution and PET image in 9L tumor hearing rats. Material and Methods: For the synthesis of $[^{18}F]$FLT, 3-N-tert-butoxycarbonyl-(5'-O-(4,4'-dimet hoxytriphenylmethyl)-2'-deoxy-3'-O-(4-nitrobenzenesulfonyl)-${\beta}$-D-threopentofuranosyl)thymine was used as a FLT precursor, on which the tert-butyloxycarbonyl group was introduced to protect N3-position and nitrobenzenesulfonyl group. Radiolabeling of nosyl substitued precursor with $^{18}F$ was performed in acetonitrile at $120^{\circ}C$ and deproteced with 0.5 N HCI. The cell uptake was measured in cultured 9L glioma cell. The biodistribution was evaluated in 9L tumor bearing rats after intravenous injection at 10 min, 30 min, 60 min and 120 min and obtained PET image 60 minutes after injection. Results: The radiochemical yield was about 20-30% and radiochemical purity was more than 95% after HPLC purification. Cellular uptake of $[^{18}F]$FLT was increased as time elapsed. At 120 min post-injection, the ratios of tumor/blood, tumor/muscle and tumor/brain were $1.61{\pm}0.34,\;1.70{\pm}0.30\;and\;9.33{\pm}2.22$, respectively. The 9L tumor was well visualized at 60 min post injection in PET image. Conclusion: The uptake of $[^{18}F]$FLT in tumor was higher than in normal brain and PET image of $[^{18}F]$FLT was acceptable. These results suggest the possibility of $[^{18}F]$FLT at an imaging agent for brain tumor.