CT Evaluation of Lymph Nodes That Merge or Split during the Course of a Clinical Trial: Limitations of RECIST 1.1

Abstract

A ssessment of tumor size change in medical imaging is an essential aspect of the clinical evaluation of cancer treatment. Thus, precise and reliable lesion quantification is essential in response evaluation criteria in clinical oncology. The most common criteria used for tumor assessment remains Response Evaluation Criteria in Solid Tumors (RECIST). RECIST is a series of response criteria initially established in 2000 and revised in 2009 (version 1.1). Per RECIST version 1.1, up to two lymph nodes with short-axis diameter equal to or more than 1.5 cm can be selected as target lesions and be evaluated over time (1,2). Despite substantial revisions made in RECIST 1.1, some vital questions and limitations remain unsolved, including interreader and intrareader variations of measurements, improper method of tumor assessment in the setting of image-based focal treatment (chemoembolization, radiofrequency ablation), and lack of tumor size change with new cancer therapies when necrosis occurs (3-5).Adjacent nodes often merge as the disease progresses. Conversely, conglomerated nodes can split into smaller nodes when they shrink in response to treatment. In merged target lymph nodes, RECIST 1.1 calculates the longest short-axis diameter perpendicular to the longest axis of the resulting node (herein known as "short axis"), while in split target lymph nodes, RECIST 1.1 measures the sum of short-axis diameters of all the resulting nodal fragments (2).Recent advancements in imaging modalities have allowed us to measure the volume of the lesions more easily. The literature indicates that volumetric measurements represent a better prediction and outcome than linear one-dimensional or two-dimensional measurements in response evaluation of cancers (6-10). Volumetric measurement is a surrogate for the number of neoplastic cells and provides a more detailed and accurate evaluation of tumor size compared with RECIST 1.1 (8,11,12).In this study, we compared the RECIST 1.1 measurement in split and merged target lymph nodes with volumetric measurement on CT scans from clinical trials. Materials and Methods PatientsIn this institutional review board-approved Health Insurance Portability and Accountability Act-compliant

Development and validation of a nomogram model for the prediction of 4L lymph node metastasis in thoracic esophageal squamous cell carcinoma

“…CT-reported positive LNs were defined as regional LNs with a short-axis diameter greater than 1.0 cm ( 16 , 17 ). A central low-density mass with an irregular or rim-like enhancement of residual lymphatic tissue was considered as LN necrosis, and conglomerate nodes merging two or more nodes were considered as LN conglomeration ( 18 – 20 ). The overall survival (OS) was measured as the date from diagnosis to the date of death, the time of last contact, or December 2020.…”