PERCIST Criteria for Response Evaluation With Solid Tumors

Chemo-radiotherapy and targeted therapy are widely used as non-surgical treatments for solid tumors. Early assessment of treatment response is considered efficient and helpful to clinical management and personalized therapy.RECIST 1.1 criteria was accepted widely. Complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD) are defined in the RECIST criteria. This type of classification divides intrinsically continuous data (tumor size) into 4 bins, losing statistical power for ease of nomenclature and convenience. The 18F-FDG PET exam is based on metabolic information and considered to overcome limitations of anatomic imaging and more suitable for assessment of therapeutic response.PERCIST 1.0 proposes a series of detailed and unambiguous regulations about standardization procedures to ensure the reproducibility. Complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD), and progressive metabolic disease (PMD) are defined in the PERCIST criteria. So far, there have several studies using metabolic-based PERCIST criteria in patients with solid tumors, including lung cancer, digestive tumor and lymphoma, etc. But all of these studies had limitations of small study sample, thus were need to be further investigated. Compared to RECIST, the advantages of PERCIST were to evaluate chemotherapy, especially targeted therapy, to distinguish PMR and SMD patients from SD group in RECIST, and to better predict the response rate. Recently, several studies applied PERCIST criteria to evaluate neoadjuvant chemotherapy in pancreatic cancer and rectal cancer, and revealed the metabolic response results were well related to pathology. All these studies conclude PERCIST criteria could help making clinical therapeutic decisions. Moreover, several studies have shown that PERCIST has advantage in predicting early response of several malignant tumors. The aim of this multicenter study is 1) to evaluate treatmen