Predictors of Early Recurrence Prior to Planned Postoperative Radiation Therapy for Oral Cavity Squamous Cell Carcinoma and Outcomes Following Salvage Intensified Radiation Therapy

Abstract

To determine predictors and outcomes for oral squamous cell carcinoma (OSCC) patients who had early recurrence before commencement of postoperative radiation therapy (PORT). 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 recurrence. 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). Six hundred and one patients were identified, of whom 513 (85%) were treated with adjuvant PORT. Eighty-eight patients (15%) had early recurrence (28 of 88; 32% were biopsy proven) before PORT (70 in the salvage group and 18 in the palliative group). On MVA, oral tongue subsite, microscopic positive resection margin, pT3-4, and pN2-3 were associated with the development of early recurrence (P<.05 for all). The 3-year OS rates for patients with OSCC treated with adjuvant and salvage PORT were 71% (95% confidence interval [CI], 67%-75%) and 41% (95% CI, 30%-56%), respectively (P<.001; median follow-up was 3.4 and 2.9years, respectively). After salvage PORT, the 3-year recurrence-free rate was 36% (95% CI, 23%-47%). On MVA, extranodal extension and volume of early recurrent gross disease were associated with poor recurrence-free rate, disease-free survival, and OS (P<.05 for all). Early recurrences are not uncommon in patients with high-risk features, Further study is required to improve prediction and outcomes of this very high-risk group.