3493 - Twelve-Month Swallowing Outcomes in a Phase II Trial of PET-Adapted Radiation for HPV-Associated Oropharynx Squamous Cell Carcinoma
Presenter(s)
L. Higgins1, K. Suresh1, S. Wilkins2, T. Lyden3, A. Blakely3, M. Ambrose3, D. A. Elliott1,4, G. Strohbehn5, M. E. Prince6, K. Casper6, A. Shuman6, C. L. Stucken6, D. Forner6, M. E. Heft-Neal6, P. Yalamanchi6, C. Brenner7, P. L. Swiecicki5, F. Worden5, M. L. Mierzwa1, and J. L. Shah1; 1Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 2University of Michigan, Department of Otolaryngology, Ann Arbor, MI, 3Department of Otolaryngology, University of Michigan, Ann Arbor, MI, 4Department of Radiation Oncology, Veterans Affairs Ann Arbor Health System, Ann Arbor, MI, 5Department of Internal Medicine, Division of Hematology and Oncology, University of Michigan, Ann Arbor, MI, 6Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 7University of Michigan, Ann Arbor, MI
Purpose/Objective(s):
A prospective single-arm phase II multicenter trial was conducted to evaluate chemoradiation (CRT) de-escalation by mid-treatment FDG-PET response in early-stage p16+ OPSCC. De-escalated patients were expected to have lower incidence of swallowing dysfunction.
Materials/Methods:
Patients with Stage I-II p16+ OPSCC were treated with radiation and concurrent weekly carboplatin/paclitaxel. Patients with ≥50% decrease in metabolic tumor volume on mid-treatment FDG-PET (obtained at fraction 10) were treated to 54 Gy in 27 fractions and remaining patients were treated with standard 70 Gy in 35 fractions. Videofluoroscopy swallow study (VFSS) was completed at 12 months post-treatment, with late swallowing dysfunction defined as overall Dynamic Imaging Grade of Swallowing Test (DIGEST) score of ≥2 at 12 months. Patients with local recurrence within 18 months of enrollment were excluded from analyses. Univariate and multivariable logistic regression models examined for associations between relevant dosimetric variables and DIGEST score ≥2.
Results:
Overall, 78 patients were enrolled on trial and 32 patients (41%) received de-escalated CRT. Twelve-month VFSS was completed in 53 patients (68%) and 10 patients (18.9%) had DIGEST ≥2 (Table 1). As expected, patients who received de-escalated therapy had significantly lower total volumes receiving 54 and 70 Gy (V54 and V70, respectively), lower volumes of superior constrictors (SC), inferior constrictors (IC), and larynx receiving 45, 50, and 55 Gy, and lower mean dose to SC, IC, and larynx (all p-values < 0.025). From univariate and multivariable regression models adjusted for smoking status (current or >10 pack years), age, and RT break, there were no statistically significant associations between V54, V70, or dose to organs at risk and DIGEST ≥2.
Conclusion:
In a phase II trial cohort receiving standard and de-escalated CRT for Stage I-II p16+ OPSCC, previously validated dosimetric predictors were not associated with 12-month swallowing dysfunction. Limitations of this study include small sample size and VFSS missingness. Further work is needed to reliably predict functional outcomes in early-stage OPSCC receiving de-escalated therapies.
Table 1: Baseline characteristics stratified by 12-month DIGEST score.
| Characteristic | 12-month DIGEST <2 (n=43) | 12-month DIGEST ≥2 (n=10) | P-value |
| Radiation Dose 70 Gy 54 Gy | 28 (65%) 15 (35%) | 5 (50%) 5 (50%) | 0.5 |
| Age (median, IQR) | 58 (53,67) | 64 (56,71) | 0.4 |
| Sex Male Female | 38 (88%) 5 (12%) | 9 (90%) 1 (10%) | >0.9 |
| Smoking Status Current or >10 PY Never or ≤ 10 PY | 32 (74%) 11 (26%) | 5 (50%) 5 (50%) | 0.15 |
| Tumor Subsite Base of Tongue Tonsil | 20 (47%) 23 (53%) | 5 (50%) 5 (50%) | >0.9 |
| AJCC 8th Ed. Stage I II | 33 (77%) 10 (23%) | 7 (70%) 3 (30%) | 0.7 |
| T-stage 1 2 3 | 20 (47%) 17 (40%) 6 (14%) | 3 (30%) 6 (60%) 1 (10%) | 0.7 |
| N-stage 0 1 2 | 1 (2%) 38 (88%) 4 (9.3%) | 0 (0%) 7 (70%) 3 (30%) | 0.3 |
| RT break (2+ days) | 2 (5%) | 2 (20%) | 0.2 |