The following is a summary of “The Effect of Intrathoracic Lesion Location on Initial Tyrosine Kinase Inhibitor Response in Advanced Oncogene-Addicted Non-Small Cell Lung Cancer: A Comparison Between RECIST 1.1 and a Novel Method of Response Assessment (MAX)” published in the December 2022 issue of Endocrinology & Metabolism by Bang et al.

Non-small cell lung cancer (NSCLC) comes in a wide variety of subtypes, each of which is linked to a unique pattern of metastasis. In addition, the progression of cancer and its response to treatment may depend on the specific anatomic location of lesions within the chest. As a result, apparent response rates, as measured by RECIST, may vary depending on the location of the lesion. The goal was to investigate this and develop location-independent measures of how well a patient responds to treatment. Cancer patients with EGFR, ALK, or ROS1-driven advanced NSCLC who underwent pre- and post-treatment imaging to assess response to targeted therapy were found.

RECIST 1.1 (unidimensional measurements) and a novel MAX methodology (bidimensional measurements) were used to independently identify and analyze lesions in the lung parenchyma, pleural space, and intra-thoracic lymph nodes, with the axis with the greatest absolute percentage change on therapy serving as the representative measurement. The RECIST study included 313 participants with 446 monodimensionally assessed lesions. There were 249 individuals included in the MAX study, and those patients had 386 lesions that were assessed in 2 dimensions. The RECIST percentage reduction and response rate were considerably affected by intrathoracic placement. The response rates for pleural, intra-parenchymal, and nodal lesions were 34.1%, 49.6%, and 68.3%, respectively (P=.0002). 

The MAX technique increased the observed treatment impact and normalized it across different intrathoracic sites. The MAX estimated response rates were 83.7%, 72.2%, and 75.4% for pleural, parenchymal, and nodal lesions, respectively (P-value =.24). Intrathoracic lesion location affects RECIST-based treatment effectiveness estimations. Further investigation into the MAX technique is warranted due to its ability to control for the location effect when assessing treatment efficacy.