Pattern of Failure of Head and Neck Malignancy (HNM) With Perineural Invasion (PNI)

Purpose/Objective(s): To evaluate treatment-related toxicity, disease control, and survival in patients with malignant melanoma of the head and neck with resected regional LN metastases treated with adjuvant hypofractionated IMRT. Materials/Methods: Between January 2004 and August 2011, 52 patients with malignant melanoma of the head and neck with regional LN metastases were treated with complete resection and adjuvant IMRT at our institution. Patients with known distant metastatic disease at the time of RT (nZ6) were excluded, leaving 46 patients for this retrospective analysis. Patients underwent neck dissection (nZ42) or wide local excision (nZ4) for regional LN involvement at initial diagnosis (nZ19) or as recurrence (nZ27). All patients had unilateral LN involvement only. Adjuvant IMRT using multiple 6 MV photon beams was delivered twice per week over 2.5 weeks for a total dose of 30 Gray in 5 fractions. The target volume included the ipsilateral (nZ44) or bilateral neck (nZ2). The primary lesion excision site was typically included in the treatment volume if the interval from excision to RTwas less than 2 years. Eighteen patients (39%) received adjuvant sargramostim (GM-CSF). Acute and late toxicities were recorded using the Common Toxicity Criteria for Adverse Events version 4. Site of first recurrence was defined as local-regional (LR, above the clavicles) or distant. Overall survival (OS), disease-free survival (DFS), and disease recurrence risks were determined using Kaplan-Meier (KM) estimates. Results: The median follow-up in living patients was 2.8 years (range, 0.2 6.9). Most patients experienced acute grade 1-2 dermatitis (80%) and mucositis (85%). Only 1 patient (2%) experienced acute grade 3 toxicity (parotiditis requiring hospitalization). A total of 8 late grade 2 toxicities requiring medical intervention were observed in 7 patients (16%), including serous otitis media (nZ2), soft tissue fibrosis (nZ2), xerostomia (nZ1), wound dehiscence (nZ1), lymphedema (nZ1), and hypothyroidism (nZ1). No patient experienced grade 3 or higher late toxicity. Site of first recurrence was LR alone (nZ5), both LR and distant (nZ1), and distant alone (nZ25). Five of the 6 LR recurrences were inside the RT target volume. In-field and total LR control at 3 years were 85% and 76%, respectively. Salvage LR treatment included revision neck dissection (nZ3) or wide local excision (nZ3). OS and DFS at 3 years were 63% and 25%, respectively. Conclusions: In patients with melanoma of the head and neck who underwent lymphadenectomy for regional LN metastases, adjuvant hypofractionated IMRT (30 Gy in 5 fractions) was associated with a high rate of in-field control and a low risk of severe toxicity. Author Disclosure: C.L. Hallemeier: None. Y.I. Garces: None. M.A. Neben-Wittich: None. K.R. Olivier: None. J.A. Garcia: None. P.D. Brown: None. R.L. Foote: None.