John A. Vargo MD, Presenter: Nothing to Disclose

Robert L. Ferris MD, PhD, Abstract Co-Author: Nothing to Disclose

David Clump, Abstract Co-Author: Nothing to Disclose

Barton F. Branstetter MD, Abstract Co-Author: Nothing to Disclose

Carl Seynnaeve MD, Abstract Co-Author: Nothing to Disclose

James Ohr DO, Abstract Co-Author: Nothing to Disclose

Michael Gibson MD, Abstract Co-Author: Nothing to Disclose

Jonas T. Johnson MD, Abstract Co-Author: Nothing to Disclose

Dwight E. Heron MD, Abstract Co-Author: Nothing to Disclose

Locally-recurrent previously-irradiated head-and-neck cancer (rHNC) remains a significant clinical challenge, with limited options for unresectable disease. Recently, SBRT ± cetuximab has emerged as a viable regimen with reduced toxicity and shorter treatment time compared to conventional options. Response evaluation in patients with recurrent disease is challenged by anatomical distortion from prior treatment and recurrent tumor. As a part of a Phase II trial examining SBRT + cetuximab in rHNC, assessment by PET/CT at 2-months was included as a secondary metric to better define the role of PET/CT as an early & more sensitive biomarker of response compared to CT alone.

From July 2007 to March 2013, patients >18 with inoperable locoregionally-confined rHNC within a previously-irradiated field receiving ≥ 60Gy, ECOG 0-1, & normal hepatic/renal function were enrolled. Patients received concurrent cetuximab (400mg/m2 on day -7 then 250mg/m2 on days 0 and +8) plus SBRT (40-44Gy in 5 fractions over 1-2 week). The primary endpoints: loco regional progression-free survival (PFS) & treatment-related toxicity (not reported here) Secondary end-points: response rates and changes in tumor glucose metabolism post-therapy as assessed by subjective interpretation of the FDG PET/CT.

Fifty patients were enrolled, of which 48 were eligible. Median follow-up for surviving patients was 18 months (range: 10 -70). Per protocol first FDG PET/CT was performed 8 week post-treatment in 44 patients (92%). Response as assessed by first PET/CT was as follows: progression 36%, stable disease 14%, partial response 30%, and complete response 21%, respectively. Complete metabolic response by first FDG PET/CT was a significant predictor of progression free survival (1-year 71% vs. 25%, p = 0.040) and overall survival (1-year 67% vs. 35%, p = 0.047).

Complete metabolic response by FDG PET/CT appears to be an early predictor of overall outcome following SBRT + cetuximab. Further ongoing analysis within this recently complete phase II trial will help to better clarify the prognostic significance of FDG-PET/CT in comparison to traditional anatomical CT-based response metrics.

In a phase II protocol examining SBRT + cetuximab for patients with rHNC, we show potential efficacy with good response rates & complete response by 2-month PET/CT may guide further management.

Vargo, J, Ferris, R, Clump, D, Branstetter, B, Seynnaeve, C, Ohr, J, Gibson, M, Johnson, J, Heron, D, The Prognostic Value of First FDG PET Response Following Re-irradiation with Stereotactic Body Radiotherapy Plus Cetuximab in Patients with Recurrent Previously-irradiated Squamous Cell Carcinoma of the Head and Neck: Results from a Phase II Trial.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14018268.html