Background: In order to improve the prognosis of gastric cancer patients, the timely identification of second primary cancers is considered to be a crucial clinical problem. Methods: We analyzed the clinicopathological data of 2,250 patients with gastric cancer with regard to both synchronous and metachronous second primary cancers. Results: Of 2,250 patients, 95 (4.2%) had a second primary cancer. Both colorectal and lung cancer were frequently detected, followed by cancer in the liver, esophagus and breast. Regarding the time of detection for such second cancers, 65% of colorectal cancers were detected synchronously, while more than 80% of lung cancers were detected metachronously. The prognosis of gastric cancer patients with a second primary cancer was more negatively influenced by a second primary cancer than by a primary gastric cancer. Conclusion: Since gastric cancer patients may develop synchronous and metachronous second cancers in other organs, effective preoperative and postoperative diagnostic modalities both for second primary cancers, as well as for the recurrence of gastric cancer, need to be developed.

Objective. We have previously demonstrated that reactive oxygen species (ROS) are involved in cartilage degradation. Decreased size of hyaluronan (HA), the major macromolecule in synovial fluid, to which it imparts viscosity, is reported in patients with arthritis. The purpose of this study was to determine the alteration in the molecular weight range of HA as a result of mechanical deformation loaded on the chondrocytes, as well as the involvement of ROS in this action.Methods. ROS were generated via the oxidation of hypoxanthine by xanthine oxidase. Cyclic tensile stretch was loaded using a vacuum-operated instrument. Levels of HA were measured using a sandwich enzyme-binding assay. Superoxide dismutase (SOD) activity and ROS were measured using water-soluble tetrazolium and a chemiluminescent probe, respectively.Results. ROS depolymerized HA molecules. Cyclic tensile stretch depolymerized HA and induced ROS. SOD inhibited not only ROS induction but also HA depolymerization caused by the mechanical stress.Conclusion. ROS play an important role in mechanical stress-induced HA depolymerization.

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