In clinical study, the RECIST guideline is used for assessing the efficacy of gastric cancer chemotherapy, but the guideline is not always suitable for clinical practice. It is not necessary in clinical practice to change treatment according to what progressive disease is by RECIST criteria, but it is important to consider comprehensive assessments of efficacy for individual patients according to disease symptoms, physical condition, diagnostic imaging, tumor markers, and empirical knowledge. It is possible to continue the same treatment regimen for progressive disease without encountering tumor-related symptoms. Besides whether regimens to be able to select for next line is important factor for changing treatment. The second-line anticancer chemotherapy drugs for gastric cancer are taxane and irinotecan. However, there are few regimens for salvage after third-line chemotherapy. When changing treatment, it is important to use key drugs for gastric cancer as much as possible. Moreover, there has been little evidence of second-line chemotherapy for gastric cancer, and selecting treatment according to the patient's condition is not yet established. It is also important to regularly put efficacy assessments into place, and understanding the efficacy of anticancer drugs and patient's condition by the assessments is related to the best changing and selecting treatment. The standard of the efficacy assessment is diagnostic imaging but not tumor markers.