Main Session
Sep
29
PQA 07 - Head and Neck Cancer, Lung Cancer/Thoracic Malignancies, and Nursing and Supportive Care
Presenter(s)
Anurag Singh, MD, FASTRO - Roswell Park Cancer Institute, Buffalo, New York
L. Jung1,2, M. K. Farrugia1, H. Yu1, V. Gupta3, R. Mcspadden1, K. E. Wooten1, M. Markiewicz1, W. L. Hicks1, and A. K. Singh4; 1Roswell Park Comprehensive Cancer Center, Buffalo, NY, 2University at Buffalo, Buffalo, NY, 3Department of Radiation Oncology, Mount Sinai Health System, New York, NY, 4Department of Radiation Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, NY
Purpose/Objective(s):
Post-treatment PET/CT is standard for response assessment in head and neck squamous cell carcinoma (HNSCC), but indeterminate findings frequently lead to repeat imaging. We hypothesized that delaying initial post-treatment PET from 12–13 weeks to =17 weeks would reduce the need for repeat PET without compromising outcomes and that repeat PET primarily provides prognostic rather than management-changing information.Materials/Methods:
We performed a retrospective analysis of 610 HNSCC patients who underwent post-treatment PET/CT following definitive therapy at one institution. Post-treatment PET was initially performed at 12–13 weeks and was subsequently shifted to approximately 17 weeks to reduce false-positive findings. Patients were grouped by timing (12–13 vs =17 weeks). For indeterminate initial scans, repeat PET was performed at a median of 91 days. Outcomes included repeat PET utilization, downstream management, and overall survival (OS). Kaplan–Meier methods and Fisher’s exact test were used.Results:
Of 610 patients, 520 had evaluable post-treatment PET. Initial imaging showed complete response (CR) in 281 (54.0%), indeterminate findings in 163 (31.3%), and progression or metastatic disease in 76 (14.6%). Repeat PET was performed in 77 patients (12.6%). Repeat PET occurred in 14.4% of patients imaged at 12–13 weeks (60/418) versus 8.9% at =17 weeks (17/192) (Fisher’s exact p=0.066). Among patients undergoing repeat PET, outcomes were CR in 38 (49.4%), incomplete response (IR) in 33 (42.9%), and progression or metastatic disease in 6 (7.8%). Repeat PET did not lead to biopsy and resulted in additional therapy in only 5 patients (6.5%), all within the non-CR group. Most patients were managed with imaging surveillance. Overall survival (OS) did not differ between patients with and without repeat PET (log-rank p=0.837). Within the repeat PET cohort, OS differed significantly by outcome (CR vs IR vs progression; log-rank p<0.001). Patients with IR demonstrated survival similar to those with progression and significantly worse than CR. Patients achieving CR on repeat PET had survival comparable to those with CR on initial imaging.Conclusion:
Repeat PET/CT rarely alters immediate management but provides strong prognostic stratification. Incomplete response identifies a high-risk group with outcomes similar to progression, suggesting a potential role for treatment escalation in future studies. Delaying post-treatment PET to =17 weeks may reduce repeat imaging without compromising outcomes. These findings support a more selective and patient-centered approach to surveillance imaging.