Comparison between RECIST and PERCIST criteria in Therapeutic Response Assessment in cases of Lymphoma

Abstract

Malignant lymphoma is one of the most common tumors worldwide that affect any age group , more frequently young adults, lymphoma being originating from blood cells, make it can easily spread to involve any organ, making its evaluation a challenging job. Besides the fact that lymphoma could be a treatable cancer emerged the importance of quantitative therapeutic response assessments in this patients with many variable evaluating methods & classifications.

CT-based RECIST is based on tumor size measurements whereby changes in tumor size are used to define complete response, partial response, and stable or progressive disease in response to therapy. Its limitations include and include considerable inter-observer variability in size measurements, inaccurate differentiation between viable and nonviable tumor resulting in underestimations of responses; overestimation of responses if tumor regrowth occurs rapidly, apparent stable disease that denotes slowly growing tumors rather than a beneficial response to treatment. RECIST provides simple guidelines for defining response or nonresponse to therapy. It is this simplicity that has led to the widespread adoption of RECIST in clinical practice.

PET-based PERCIST is based on tumor viability assessment by detecting FDG activity & changes are used to define complete metabolic response, partial metabolic response, and stable or progressive metabolic disease in response to therapy. Quantitative 18F-FDG PET is thought to overcome anatomical methods of assessment limitations and is believed to be a more satisfactory assessment tool for evaluating therapeutic response.