Antineoplastic Combined Chemotherapy Protocols/therapeutic use; Bone Neoplasms/mortality; Lung Neoplasms/mortality; Neoplasm Recurrence, Local/mortality; Peritoneal Neoplasms/mortality; Stomach Neoplasms/mortality; Adult; Aged; Aged, 80 and over; Bone Neoplasms/drug therapy; Bone Neoplasms/secondary; Female; Follow-Up Studies; Humans; Lung Neoplasms/drug therapy; Lung Neoplasms/secondary; Lymphatic Metastasis; Male; Middle Aged; Neoplasm Recurrence, Local/drug therapy; Neoplasm Recurrence, Local/pathology; Neoplasm Staging; Peritoneal Neoplasms/drug therapy; Peritoneal Neoplasms/secondary; Prognosis; Prospective Studies; Retrospective Studies; Stomach Neoplasms/drug therapy; Stomach Neoplasms/pathology; Survival Rate; Time Factors; Young Adult