(A611) Radiation-Related Oral Cavity Malignancies following Radiotherapy Treatment for HPV-Associated Oropharyngeal Cancer: An Institutional Case Series

Monday, October 13, 2025

12:00 PM - 1:00 PM EDT

Location: OTO EXPO, Posters

Presenting Author(s)

Nina D. Ham, BA

Medical Student
UC Davis School of Medicine
Sacramento, California, United States

Co-Author(s)

Soroush Ershadifar, MD

PGY-1
University of Kansas
Kansas City, Kansas, United States

Co-Author(s)

SR

Shyam Rao, MD

Radiation Oncology
Department of Radiation Oncology, University of California-Davis, Sacramento, California, USA
Sacramento, California, United States
ML

Michael Li, MD

Department of Otolaryngology–Head and Neck Surgery, University of California–Davis, Sacramento, California, USA, United States
SF

Scott C. Fuller, MD

Clinical Professor
Department of Otolaryngology–Head and Neck Surgery, University of California–Davis, Sacramento, California, USA
Sacramento, California, United States
AB

Andrew C. Birkeland, MD

Associate Professor
UC Davis Health
Sacramento, CA, United States
Marianne Abouyared, MD

Associate Professor
University of California, Davis
Sacramento, California, United States

Senior Author(s)

Arnaud Bewley, MD

Assistant Professor
Department of Otolaryngology–Head and Neck Surgery, University of California–Davis, Sacramento, California, USA
Sacramento, California, United States

Disclosure(s):

Nina D. Ham, BA: No relevant relationships to disclose.

Soroush Ershadifar, MD: No relevant relationships to disclose.

Scott C. Fuller, MD: No relevant relationships to disclose.

Andrew C. Birkeland, MD: No relevant relationships to disclose.

Marianne Abouyared, MD: No relevant relationships to disclose.

Introduction: Prior studies have reported an elevated risk of secondary malignancies in the irradiated treatment field of cancer patients. The aim of this study was to characterize oral cavity cancer (OCC) developing in HPV-associated OPC patients who received radiation therapy as part of their treatment.

Methods: We identified OCCs that developed within the radiation treatment field at least three years after therapy for OPC. Patients with documented pathology reports of HPV-associated OPC (p16+) were included. Patients with missing HPV status were presumed to be HPV-associated if they lacked other traditional risk factors.

Results: 22 patients with OCC following treatment of OPC were identified. Average age of diagnosis at the time of initial OPC was 60.5 years old (SD = 8.1 years). The majority of the patients were male (n=20, 91%) and had a remote history of tobacco use (n = 12, 54%). 15 (68%) patients received radiotherapy as part of definitive treatment for OPC (with or without concurrent chemotherapy), while others underwent radiation treatment as adjuvant therapy. Average time to diagnosis from first and second primary tumors was 8.6 years (standard deviation = 4.8 years). The majority of patients developed second primaries of the oral tongue (n = 15, 68%) and mandibular alveolus (n = 4, 18%) and all were non-HPV associated squamous cell carcinoma (SCC). For staging, the majority of the patients were staged as N0 (n = 16, 82%) with T1/2 staging (n = 15, 68%) while 7 (35%) presented with T3/4 staging. On final pathology report, 3 (14%) patients had positive margin status, 9 (41%) had perineural invasion, and 5 (23%) had lymphovascular invasion. The 2-year survival rate and median overall survival after diagnosis of radiation-related malignancy was 60% and 2.5 years respectively.

Conclusions: We present a descriptive analysis of a cohort of patients who developed second primary OCC following radiation therapy for OPC. Given the dramatic rise in the number of OPC survivors, further research on role of radiation therapy in developing second OC malignancies and identifying patients who might be at higher risk is critical.