3637 - HPV-DNA Titers and Tumor Volume Correlation in Human Papillomavirus Related Oropharyngeal Squamous Cell Carcinoma

S. Devpura¹, A. I. Ghanem^1,2, M. Gilbert¹, S. A. R. AlKhatib¹, H. Bagher-Ebadian¹, S. Tam³, V. Wu³, K. Thind¹, and F. Siddiqui⁴; ¹Department of Radiation Oncology, Henry Ford Health, Detroit, MI, ²Alexandria Clinical Oncology Department, Alexandria University, Alexandria, Egypt, ³Department of Otolaryngology, Henry Ford Health, Detroit, MI, ⁴Department of Radiation Oncology, Henry Ford Cancer Institute, Detroit, MI

Purpose/Objective(s): For human papilloma virus related (HPV+ve) primary oropharyngeal squamous cell carcinoma (OPC), blood tests can quantify circulating cell free tumor tissue modified viral (TTMV)-HPV DNA at diagnosis and after treatment during follow-up. The purpose of this study is to investigate the correlation between baseline tumor volume and pre-treatment TTMV-HPV DNA titers for HPV+ve OPC. Materials/

Methods: We queried our institutional database to identify non-metastatic HPV+ve OPC patients with available pre-treatment TTMV-HPV 16 DNA scores. All patients have the gross tumor volume (GTV) for the primary (GTVp), involved lymph nodes (GTVn) and total tumor volume (TTV= GTVp + GTVn) calculated in cc on the contrast enhanced radiation treatment planning CT-scan. We excluded patients with negative and intermediate TTMV-HPV 16 pre-treatment scores, those with N0 OPC and those with HPV+ve nodes with no detected primary. Spearman’s rho correlation (two tailed, significance at the 0.01 level) was performed to determine correlations among all tumor volumes and the pretreatment TTMV-HPV 16 DNA scores.
Results: We identified 29 patients who met our inclusion criteria: 90% were males, 89.6% white, median age was 64 (range, 42-81) years, 24% were current smokers and 20.1% were former smokers with median pack-years of 22.5 (range, 1.8-61) and 48.3% reported a history of alcohol use. More than half of the patients had base of the tongue location (51.7%) followed by tonsil (41.4%), with T1, T2, T3 and T4 tumors detected in 27.6%, 27.6%, 27.6% and 17.2%, whereas 38% and 62% had N2 and N1 disease, respectively. Mean (standard deviation) GTVp, GTVn, and TTV were 30.2 ± 30.9, 28.3 ± 30.4, and 58.5 ± 47.2 cc, respectively and median (range) of TTMV-HPV 16 DNA score was 483 (19-126009) fragments/ml plasma. Spearman’s rho showed a significant positive moderate correlation with both GTVn and TTV and TTMV-HPV 16 DNA scores (See Table 1 below). Statistically significant correlation was not observed with GTVp.
Conclusion: Nodal tumor volume and total tumor volume showed moderate positive correlation with pretreatment TTMV-HPV-16 DNA titers for HPV+ve OPC. Abstract 3637 – Table 1: Summary of Spearman’s rho correlation for 29 patients *. Correlation is significant at the 0.05 level (2-tailed).

Parameter	Correlation Coefficient	Significance (2-tailed)
GTVn vs. HPV-DNA	0.452*	0.014
GTVp vs. HPV-DNA	0.167	0.385
TTV vs. HPV-DNA	0.446*	0.015