Sparing Bilateral Neck Level IB in Oropharyngeal Carcinoma and Xerostomia Outcomes

Abstract

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.

The role of parotid gland irradiation in the development of severe hyposalivation (xerostomia) after intensity-modulated radiation therapy for head and neck cancer: Temporal patterns, risk factors, and testing the QUANTEC guidelines

“…This indicates that another cut-off value on the ipsilateral mean dose might be more suitable to prevent xerostomia within our dataset. Interestingly, in a recent study from our institution patient reported xerostomia outcome was better correlated with significant reduction in the mean radiation dose to the bilateral submandibular salivary glands, oral cavity, and contralateral parotid gland if using target delineation-sparing bilateral neck level 1B (Tam et al, 2015). The study by Tribius et al showed that the incidence of xerostomia in patients with bilateral parotid gland sparing to <26 Gy was significantly lower when compared to patients with one parotid gland sparing to >26 Gy (Tribius et al, 2013).…”

Implementation of submandibular gland transfer: A multi‐institutional study of feasibility and time to treatment

“…In patients undergoing primary surgery, median time was 32 days (IQR, and in patients undergoing primary nonsurgical therapy, median time was 46.5 days (IQR, [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54]. Time from tissue diagnosis to SMGT was 28 days (IQR, 21-44), and from surgery to adjuvant therapy was 33 days (IQR, [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47]. Thirteen patients suffered a treatment delay: seven patients due to >60 days from diagnosis to treatment initiation (7/49; 14%) and six due to >6 weeks from surgery to adjuvant radiation (6/19; 32%).…”

“…33,34 Other reports demonstrate that IMRT only reduces the SMG dose to [35][36][37][38][39][40][41][42][43][44][45] Gy. [35][36][37] It has been recommended that doses beyond 25 Gy should be avoided if significant salivary function is to be preserved. 33,38 Furthermore, self-reported degree of xerostomia at rest is only 30% less severe after IMRT compared to conventional RT, and xerostomia during meals is only 37% less severe .…”

Successes and Failures of Combined Modality Therapies in Head and Neck Cancer

“…We continue to explore a variety of delivery techniques such as volumetricmodulated arc therapy (VMAT) or TOMOtherapy to maximize normal tissue sparing while sending homogenous doses of radiation to the intended targets. Salivary function and quality of life continue to improve as radiation oncologists use parotid and submandibular sparing techniques with no decrease in safety [9][10][11]. Beyond decreasing long term side effects, IMRT-based approaches may also improve cancer specific survival [12].…”