Objectives
To assess whether sparing neck level IB in target delineation of node positive (N+) oropharyngeal carcinoma (OPC) can improve xerostomia outcomes without compromising local-regional control (LRC).
Methods
125 N+ OPC patients with a median age of 57 years underwent chemoradiation between 5/10 and 12/11. 74% of patients had T1-2 disease, 26% T3-4, 16% N1, 8% N2A, 48% N2B, 28% N2C; 53% base of tongue, 41% tonsil, and 6% other. Patients were divided into those who had target delineation sparing of bilateral level IB (the spared cohort) vs. no sparing (the treated cohort). Sparing of contralateral high level II nodes was also performed more consistently in the spared cohort. A prospective xerostomia questionnaire (patient reported) was given at each patient follow-up visit to this cohort of patients to assess late xerostomia. Clinical assessment (observer rated) at each patient follow-up visit was also recorded.
Results
The 2-year LRC for the spared and treated cohorts was 97.5% and 93.8%, respectively (median follow-up, 23.2 months). No local-regional failures occurred outside of treatment fields. The spared cohort experienced significant benefits in patient-reported xerostomia summary scores (P = 0.021) and observer-rated xerostomia scores (P = 0.006). In addition, there were significant reductions in mean doses to the ipsilateral submandibular gland (SMG; 63.9 Gy vs. 70.5 Gy; P < 0.001), contralateral SMG (45.0 Gy vs. 56.2 Gy; P < 0.001), oral cavity (35.9 Gy vs. 45.2 Gy; P < 0.001), and contralateral parotid gland (20.0 Gy vs. 24.4 Gy; P < 0.001).
Conclusions
Target delineation sparing of bilateral level IB nodes in N+ OPC reduced mean doses to salivary organs without compromising LRC. Patients with reduced target volumes had better patient-reported xerostomia outcomes.