“The Benefit Of Positron Emission Tomography/Computed Tomography In Stage I And Stage II Melanomas With High-Risk Decisiondx-Melanoma Scores”

Abstract

Introduction Early detection of melanoma is instrumental as the 5-year survival decreases from 93.3% to <50% when metastases are present. 1 - 3 Distinguishing which patients require closer follow-up can be difficult for melanoma patients. Developments by Castle Biosciences’ (Friendswood, TX) DecisionDx-Melanoma (DDx-M) use 31 melanoma associated genes to stratify melanomas into 4 classes with 1A having lowest risk of morbidity and mortality and 2B the highest. 5 We assessed the benefit of providing additional 18FDG-PET-CT and brain MRI to genetically high-risk patients who may have otherwise been overlooked. Methods 297 patients at our institution had biopsies sent for DDx-M between 2014 and 2021. Patients found to have Class 2 melanomas received additional screening with yearly 18FDG-PET-CT scans and brain MRIs. Patients with Class 2 DDx-M scores and negative SLNB were included in the study. 66 met inclusion criteria and received imaging. Results Within 3 years of follow-up, 8/66 (12.1%) patients had metastases detected by 18FDG-PET-CT scans. No patients with stage IA or IB went on to develop metastases. Discussion 18FDG-PET-CT scans detect metastases in < 3% of the time when all stage I and II patients are scanned; however, by using DDx-M in our screening protocols, we achieved a detection rate of 12.1%. 6 , 7 These patients went on to receive treatment and would have otherwise progressed undetected, leading to higher morbidity and mortality. Conclusion We suggest all patients with initial stage II or above melanomas receive a DDx-M score and those with class 2 receive yearly 18FDG-PET-CT/brain MRI imaging.