American Statistical Association New York City Metropolitan Area Chapter Memorial Sloan-Kettering Cancer Center Biostatistics Seminar

The recently revised Response Evaluation Criteria for Solid Tumors (RECIST 1.1) recommends measuring up to a total of five lesions per patient when measuring tumor burden in patients with multiple lesions. This recommendation represents a change from the previous guidelines (RECIST 1.0) which advise measuring up to a total of ten target lesions per patient. There are no existing guidelines which specify the minimum number of lesions that should be measured. In this talk, we will derive an approximation of the distribution for the ratio that quantifies the relative percent change in tumor burden between a baseline and follow-up measurement. We aim to extend this theory to look at the conditional distribution of the relative percent change in tumor burden when a subset of lesions are measured given knowledge of the distribution when all lesions are measured. We can then use the conditional distribution to calculate the sensitivity and specificity of the response assessment based on a subset of lesions. These metrics are familiar to radiologists and clinicians and have the potential to help guide them in their choice of the minimum number of lesions that needs to be measured in a given application.