John Martin Floberg MD, PhD, Presenter: Nothing to Disclose

Pranshu Mohindra MD, MBBS, Abstract Co-Author: Nothing to Disclose

Nevein F. Ibrahim MD, Abstract Co-Author: Nothing to Disclose

Samuel Barasch MD, Abstract Co-Author: Nothing to Disclose

Heather M Geye, Abstract Co-Author: Nothing to Disclose

David T. Yang MD, Abstract Co-Author: Nothing to Disclose

Scott B. Perlman MD, Abstract Co-Author: Nothing to Disclose

Timothy M McCulloch MD, Abstract Co-Author: Nothing to Disclose

Greg Hartig MD, Abstract Co-Author: Nothing to Disclose

Paul M. Harari MD, Abstract Co-Author: Nothing to Disclose

Randall J. Kimple MD, PhD, Abstract Co-Author: Nothing to Disclose

To investigate the prognostic interplay of HPV status and PET-based metrics including maximum standardized uptake value (SUVmax), peak SUV (SUVpeak), metabolic tumor volume (MTV), and tumor glycolytic activity (TGA) in OP-SCC.

With IRB approval, we identified 352 patients with OP-SCC treated with radiotherapy from 1990-2010. Patients with pre-treatment PET scans and known HPV status were identified. SUVmax, SUVpeak, MTV (all tumor above 50% of SUVmax), and TGA (MTV*SUVmean) were obtained for both primary tumor (P) and lymph nodes (N). Means were compared using the t-test. Kaplan-Meier log-rank test and Cox regression analysis were performed for freedom from recurrence (FFR) and overall survival (OS); patients distributed across median values.

125 patients had PET scans available for analysis (mean follow-up 2.8 years), of which HPV status was available for 72 patients (60 positive, 12 negative). The mean P- and N- SUVmax, SUVpeak, MTV, and TGA values were not significantly different between the HPV positive and negative groups. Measures predictive of 3-year OS included low P-TGA (92 v. 76%, p=0.02) and low P-MTV (90 v. 85%, p=0.05). Low P-TGA was also predictive of improved FFR (94 v. 77%, p=0.01). Non-significant but distinct separation of FFR survival curves was seen with P-SUVmax, SUVpeak, and MTV. Similar separation was noted in P-FFR and distant-FFR by using primary tumor metrics, while nodal-metrics did not appear to display any trends. On Cox regression analysis for FFR, HPV status was the dominant factor when compared to each of the PET-metrics individually, except P-TGA which was also independently significant (HR: 0.19, p=0.01) and P-SUVmax (HR: 0.3, p=0.09). In addition to HPV status, both P-TGA and P-SUVmax provided additional stratification of patients into four separate cohorts based on FFR, with significant stratification effect in the HPV positive population.

While the dominant prognostic impact of HPV status is clearly noted, PET-metrics, particularly P-TGA and P-SUVmax, may provide additional prognostic information in OP-SCC. The interplay of these important prognostic factors will be further defined using large prospective databases.

PET imaging metrics provide additional stratification of patient cohorts beyond HPV status. This prognostication, if validated prospectively, could help further individualize treatment recommendations.

Floberg, J, Mohindra, P, Ibrahim, N, Barasch, S, Geye, H, Yang, D, Perlman, S, McCulloch, T, Hartig, G, Harari, P, Kimple, R, Prognostic Interplay of Positron Emission Tomography (PET)-based Metrics and Human Papillomavirus (HPV) Status in Oropharyngeal Squamous Cell Carcinoma (OP-SCC).  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14008870.html