Jacob L. Glass and Jedd D. Wolchok
• The motivation behind the development of objective response criteria is to objectively measure the effect of CA tx and use such measurements as a basis for rigorous comparison of proposed Rx being evaluated in clinical trials
• Criteria used have evolved over time as clinical imaging technology has adv
• Published by the WHO, these were the first standardized tumor evaluation criteria (WHO Handbook For Reporting Results for Cancer Treatment 1979).
• Designed for categorization of clinical or x-ray evaluations
• Measurable disease: To be measured in 2 dimensions for skin lesions, one for lesions in which only one measurement is appropriate (such as liver enlargement), or as a sum of diameters when multiple lesions are present in the same organ
• Unmeasurable disease: Egs given are lymphangitic pulm mets, skin involvement in breast CA, and abdominal masses that can be palpated but not measured
• Bony disease: Evaluated by x-ray
RECIST: Response Evaluation Criteria In Solid Tumors (version 1.1)
• An update on the original WHO criteria → first version of these criteria was developed to be more given the widespread use of adv imaging modalities (J Natl Cancer Inst 2000;205:216); update was based on evaluation of data measured according to the original RECIST criteria, now including changes to the number and size of lesions evaluated, evaluation of pathologic LNs, and interpretation of PET imaging (Eur J Cancer 2009;228:247)
• Measurable lesions: 10 mm on CT or clinical exam; 20 mm on x-ray. Pathologic LNs >= 15 mm in short axis by CT. X-ray measurements discouraged.
• Unmeasurable lesions: <10 mm, pathologic LNs >= 10 mm but <15 mm in short axis. This includes leptomeningeal disease, ascites, pleural/pericardial effusions, inflammatory breast tissue, lymphangitic involvement of skin or lung, or abdominal masses on clinical exam not reproducible on imaging. Generally, previously treated lesions are included in this category.
• Target lesions: Identified lesions in the baseline scan up to a total of 5, with a maximum of two per organ. These are to be followed on future scans, and the largest lesions as well as those for which reproducible measurements are expected should be prioritized.
irRC: Immune-related Response Criteria
The advent of targeted CA Rx prompted this update to the RECIST criteria. The major change is the addition of evaluation timing as well as the allowance for some ↑ in tumor burden as long as it is not sustained, given the transient disease flares that may be seen with targeted agents (Clin Cancer Res 2009;7412:7420)
SPD: Sum of products of two largest perpendicular diameters of a given lesion
Tumor burden = SPDindex lesions + SPDnew, measurable lesions
• Index lesions: Identified on baseline scan; up to 5 lesions per organ, 10 visceral lesions, and 5 cutaneous lesions
• New, measurable lesions: Identified on subsequent scans; ≥(5 × 5 mm), up to 5 new lesions per organ, 5 new cutaneous lesions, and 10 new visceral lesions