Clinical Investigation Predictors of Early Recurrence Prior to Planned Postoperative Radiation Therapy for Oral Cavity Squamous Cell Carcinoma and Outcomes Following Salvage Intensified Radiation Therapy Ali Hosni, PhD,* Shao Hui Huang, MSc,* Kevin Chiu, MD,* Wei Xu, PhD, y Jie Su, MSc, y Andrew Bayley, MD,* Scott V. Bratman, PhD,* John Cho, PhD,* Meredith Giuliani, MBBS,* John Kim, MD,* Brian O’Sullivan, MD,* Jolie Ringash, MD,* John Waldron, MD,* Anna Spreafico, PhD, z Eugene Yu, MD, x John R. de Almeida, MSc, k Eric Monteiro, MSc, k Douglas B. Chepeha, MD, k Jonathan C. Irish, MSc, k David P. Goldstein, MSc, k and Andrew Hope, MD* Departments of *Radiation Oncology, y Biostatistics, z Medical Oncology, x Medical Imaging, and k OtolaryngologyeHead and Neck SurgeryeSurgical Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada Received Jun 4, 2018. Accepted for publication Sep 11, 2018. Summary Identification of recurrence before planned postoperative radiation therapy (PORT) in oral squamous cell carci- noma is critical to allow treatment intensification. Retrospective review was performed for 601 patients with oral squamous cell car- cinoma treated with PORT after curative-intent surgery. We have identified rates and Purpose: To determine predictors and outcomes for oral squamous cell carcinoma (OSCC) patients who had early recurrence before commencement of postoperative ra- diation therapy (PORT). Methods: Retrospective review was performed for patients with OSCC treated with PORT between 2003 and 2015 after curative-intent surgery. Early recurrence was defined as tumor recurrence after surgical resection and before initiating planned PORT. Patients were classified into the following groups: (1) adjuvant PORT group (no early recurrence), (2) salvage PORT group (locoregional early recurrence), and (3) palliative PORT group (locoregional and distant early recurrence). For the whole cohort, multivariable analysis (MVA) was applied to identify predictors of early recur- rence. In the salvage group, the post-PORT recurrence-free rate was estimated, and MVA was used to identify predictors of recurrence-free rate, disease-free survival, and overall survival (OS). Reprint requests to: Ali Hosni, PhD, Princess Margaret Cancer Centre, 610 University Ave, Toronto, Ontario, Canada M5G 2M9. Tel: (416) 946- 2919; E-mail: Ali.Hosni@rmp.uhn.on.ca Funding sources of the work: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Conflict of interest: none. Supplementary material for this article can be found at https:// dx.doi.org/10.1016/j.ijrobp.2018.09.013. Int J Radiation Oncol Biol Phys, Vol. 103, No. 2, pp. 363e373, 2019 0360-3016/$ - see front matter Ó 2018 Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.ijrobp.2018.09.013 Radiation Oncology International Journal of biology physics www.redjournal.org