ctDNA as an Adjunct to Posttreatment PET for Head and Neck Cancer Recurrence Risk Assessment.

Area of Science:

• Oncology
• Molecular Diagnostics
• Cancer Research

Background:

• Minimal residual disease (MRD) detection is crucial for managing solid tumors.
• Circulating tumor DNA (ctDNA) analysis offers a non-invasive method for MRD detection.
• Positron emission tomography (PET) has limitations in identifying recurrence in head and neck cancers.

Purpose of the Study:

• To evaluate the utility of ctDNA detection for identifying MRD in head and neck squamous cell carcinoma (HNSCC) patients post-treatment.
• To compare the efficacy of ctDNA detection with PET scans in predicting disease recurrence.
• To assess ctDNA's role as an adjunct tool to improve recurrence risk stratification.

Main Methods:

• Retrospective study of 29 HNSCC patients treated between August 2021 and January 2023.
• ctDNA levels were analyzed using a personalized, tumor-informed, multiplex PCR NGS assay at multiple time points post-treatment.
• Primary outcome: recurrence-free probability (RFP); Secondary outcomes: OS, sensitivity, specificity, NPV, and PPV for ctDNA and PET.

Main Results:

• ctDNA was detected in 7 patients, all of whom experienced disease recurrence.
• Posttreatment ctDNA detection significantly correlated with a higher risk of recurrence (HR: 9.94, P=.015).
• ctDNA demonstrated 100% specificity and 78% sensitivity for recurrence detection, with 91% NPV and 100% PPV, outperforming PET in specificity and PPV.

Conclusions:

• ctDNA detection is a highly specific and sensitive method for identifying recurrence in HNSCC patients.
• ctDNA serves as an effective adjunct to PET scans, particularly when PET results are inconclusive.
• Incorporating ctDNA analysis can enhance posttreatment surveillance and guide clinical decision-making for HNSCC management.