Using Response Evaluation Criteria in Solid Tumors in real-world evidence cancer research.

Aim: Real-world evidence of charted treatment responses to cancer drug therapy was compared with medical record derived radiographic measurements of target lesions per Response Evaluation Criteria in Solid Tumors (RECIST).

Materials & Methods: 15 physicians treating 59 metastatic Merkel cell cancer (mMCC) patients contributed patient-level data. A comparison of medical record reported best response with radiographic measurements per RECIST of pre- and post-treatment target lesions.

Results: RECIST response rates were significantly lower compared with medical record reported with a concordance of 43.2% (95% CI: 28.0-58.4%).

Conclusion: Subjective assessment of tumor response collected via traditional chart abstraction may overestimate benefit and limit the potential role of real-world evidence in value-based care research. The use of target lesion measurements presents an attractive alternative that better aligns with trial results.