New approaches for precise response evaluation in hepatocellular carcinoma

With the increasing clinical use of cytostatic and novel biologic targeted agents,conventional morphologic tumor burden assessments,including World Health Organization criteria and Response Evaluation Criteria in Solid Tumors,are confronting limitations because of their difficulties in distinguishing viable tumor from necrotic or fibrotic tissue.Therefore,the investigation for reliable quantitative biomarkers of therapeutic response such as metabolic imaging or functional imaging has been desired.In this review,we will discuss the conventional and new approaches to assess tumor burden.Since targeted therapy or locoregional therapies can induce biological changes much earlier than morphological changes,these functional tumor burden analyses are very promising.However,some of them have not gone thorough all steps for standardization and validation.Nevertheless,these new techniques and criteria will play an important role in the cancer management,and provide each patient more tailored therapy.

Objective response rate assessment in oncology: Current situation and future expectations

The tumor objective response rate(ORR)is an important parameter to demonstrate the efficacy of a treatment in oncology.The ORR is valuable for clinical decision making in routine practice and a significant end-point for reporting the results of clinical trials.World Health Organization and Response Evaluation Criteria in Solid Tumors(RECIST)are anatomic response criteria developed mainly for cytotoxic chemotherapy.These criteria are based on the visual assessment of tumor size in morphological images provided by computed tomography(CT)or magnetic resonance imaging.Anatomic response criteria may not be optimal for biologic agents,some disease sites,and some regional therapies.Consequently,modifications of RECIST,Choi criteria and Morphologic response criteria were developed based on the concept of the evaluation of viable tumors.Despite its limitations,RECIST v1.1 is validated in prospective studies,is widely accepted by regulatory agencies and has recently shown good performance for targeted cancer agents.Finally,some alternatives of RECIST were developed as immune-specific response criteria for checkpoint inhibitors.Immune RECIST criteria are based essentially on defining true progressive disease after a confirmatory imaging.Some graphical methods may be useful to show longitudinal change in the tumor burden over time.Tumor tissue is a tridimensional heterogenous mass,and tumor shrinkage is not always symmetrical;thus,metabolic response assessments using positron emission tomography(PET)or PET/CT may reflect the viability of cancer cells or functional changes evolving after anticancer treatments.The metabolic response can show the benefit of a treatment earlier than anatomic shrinkage,possibly preventing delays in drug approval.Computer-assisted automated volumetric assessments,quantitative multimodality imaging in radiology,new tracers in nuclear medicine and finally artificial intelligence have great potential in future evaluations.