3648 - Improved Outcomes with Adjuvant Radiotherapy for Resected Squamous Cell Carcinomas of the Retromolar Trigone, Alveolar Ridge & Buccal Mucosa
Presenter(s)
A. A. Vera1, C. T. Wilke2, D. A. Clump II3, D. E. Heron4, S. Kim5, S. Sridharan6, U. Duvvuri7, H. D. Skinner1, and Y. M. Mowery1; 1Department of Radiation Oncology, UPMC Hillman Cancer Center, Pittsburgh, PA, 2Department of Radiation Oncology, University of Pittsburgh Medical Center, Pittsburgh, PA, 3Department of Radiation Oncology, West Virginia University School of Medicine, WVU Cancer Institute, Morgantown, WV, 4American College of Radiation Oncology (ACRO), Bethesda, MD, 5Department of Otolaryngology–Head and Neck Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, 6Department of Otolaryngology, Division of Head and Neck Surgery, UPMC, Pittsburgh, PA, 7Department of Otolaryngology, NYU Grossman School of Medicine, New York, NY
Purpose/Objective(s):
To evaluate the effects of adjuvant radiotherapy (RT) on outcomes for patients (pt) with resected retromolar trigone (RMT), alveolar ridge (AR), & buccal mucosa (BM) squamous cell carcinoma (SCC). We hypothesized that adjuvant radiotherapy (RT) would be associated with improved recurrence-free survival (RFS) and overall survival (OS).Materials/Methods:
Adults s/p surgical resection (Sx) ± RT for RMT, AR, or BM SCC (2002-21) were evaluated in a single-institution retrospective analysis. RFS & OS were measured from surgery by Kaplan-Meier method & compared by log-rank or Cox regression. To mitigate selection bias for RT, propensity scores (PS) were generated by multiple logistic regression based on age, tobacco use, EtOH use, LVSI, margin status, grade, PNI, T & N category, then incorporated into PS-adjusted Cox models.Results:
Among 219 pt with 9.3 yr median f/u, 37% recurred (Table 1). Most recurrences were local in both cohorts. On unadjusted KM, the Sx only vs Sx + RT cohorts had similar RFS (HR 0.99, 95% CI 0.61 – 1.61) & OS (HR 1.03, 95% CI 0.70 – 1.51), despite higher risk pathology in the RT group (Table 1). Median RFS was 9.96 yr for Sx & undefined for Sx + RT, with median OS of 7.26 & 6.98 yr, respectively. After PS adjustment, RT was associated with improved RFS (HR 0.52, 95% CI 0.26 – 0.99) & OS (HR 0.53, 95% CI 0.31 – 0.90).Conclusion:
Retromolar trigone, alveolar ridge, & buccal mucosa SCC have substantial recurrence risk, with predominantly local failures. Despite enrichment of adverse features in the RT cohort, adjuvant RT was independently associated with improved RFS & OS after adjustment.| Sx (n=160; 73.1) | Sx + RT (n=59; 26.9) | p-value | |
| n (%) | n (%) | ||
| Age (y) Median (IQR) <65 >65 | 69 (62–78) 51 (31.9) 109 (68.1) | 63 (46 – 69) 32 (54.2) 27 (45.8) | 0.0004 0.003 |
| Sex Male Female | 89 (55.6) 71 (44.4) | 30 (50.8) 29 (49.2) | 0.54 |
| Tobacco Yes No Unk | 101 (63.1) 56 (35) 3 (1.9) | 53 (89.8) 6 (10.2) 0 (0) | 0.0002 |
| EtOH Yes No Unk | 79 (49.4) 72 (45) 9 (5.6) | 40 (67.8) 18 (30.5) 1 (1.7) | 0.04 |
| Site RMT AR BM | 44 (27.5) 113 (70.6) 3 (1.9) | 36 (61) 22 (37.3) 1 (1.7) | <0.0001 |
| pT T1 T2 T3 T4 | 63 (39.4) 47 (29.4) 7 (4.4) 43 (26.9) | 4 (6.8) 3 (5.1) 6 (10.2) 46 (78) | <0.0001 |
| pN Nx N0 N1 N2 N3 | 35 (21.9) 98 (61.3) 13 (8.1) 11 (6.9) 3 (1.9) | 0 (0) 30 (50.8) 9 (15.3) 16 (27.1) 4 (6.8) | <0.0001 |
| Grade 1 2 3 Unk | 39 (24.4) 102 (63.8) 13 (8.1) 6 (3.8) | 5 (8.5) 45 (76.3) 9 (15.3) 0 (0) | 0.0097 |
| LVSI No Yes Unk | 140 (87.5) 18 (11.3) 2 (1.3) | 41 (69.5) 12 (20.3) 6 (10.2) | 0.0664 |
| PNI No Yes Unk | 118 (73.8) 32 (20) 10 (6.3) | 35 (59.3) 24 (40.7) 0 (0) | 0.0057 |
| ENE No Yes Unk or N/A | 20 (12.5) 13 (8.1) 127 (79.4) | 16 (27.1) 15 (25.4) 28 (47.5) | <0.0001 |
| Margin - + Unk | 149 (93.1) 7 (4.4) 4 (2.5) | 37 (62.7) 7 (11.9) 5 (8.5) | 0.0159 |
| Recurrence No Yes Local only Regional only Locoregional Local + Met Met only | 101 (63.1) 59 (36.9) 37 (62.7) 5 (8.5) 9 (15.3) 7 (11.9) 1 (1.7) | 37 (62.7) 22 (37.3) 14 (63.6) 3 (13.6) 1 (4.5) 1 (4.5) 3 (13.6) | >0.9999 |