Abstract: Most anticancer drugs are effective only in subgroups of patients, which makes the individualization of tumor response monitoring quite in need. Since the current anatomic imaging has certain limitations for this utility, and the clinical evidence of ¹⁸F-FDG PET from meta-analysis is increasing, this study gives a comprehensive review of the performance of PET in monitoring response of a variety of tumors. Given the early metabolic characterization of tumors by PET, this technology exhibited special advantages to traditional imaging modalities and generally yielded high accuracies in tumor response assessment in many meta-analyses. In certain type of tumors as malignant lymphoma, PET has recently been placed to a central role in defining tumor response in international criteria. In other tumors as non-small cell lung cancer, breast cancer, esophageal cancer, adenocarcinomas of the esophagogastric junction, rectal cancer and gastrointestinal stromal tumor, questions remain due to lack of standard regimen of PET and heterogeneity between individual study results. Besides, certain numbers of false positive and false negative results of PET still call for caution in clinical scenarios. More prospective and large sampled random trials are warranted to fully validate and position PET in tumor management.