Refining Target Volume Coverage After Parotidectomy for Cutaneous Squamous Cell Carcinoma: Omission of the Cervical Neck From the Radiation Field.

ABSTRACT

Purpose: For patients without pathologic evidence of cervical disease after neck dissection for cutaneous squamous cell carcinoma involving the parotid region, inclusion of the ipsilateral cervical neck in the postparotidectomy radiation volume is routinely performed. We report our experience with selective avoidance of the ipsilateral neck for patients undergoing postoperative radiation to the parotid bed. Methods and Materials From January 2014 to December 2023, a total of 30 consecutive patients underwent postoperative radiation after parotidectomy for cutaneous squamous cell carcinoma involving the parotid area. All patients had previously had a neck dissection confirming pathologic N0 disease. Treatment was delivered using intensity modulated radiation therapy to a median dose of 60 Gy (range, 56-66 Gy). The radiation target volumes included the parotid bed only, with deliberate avoidance of the ipsilateral cervical neck. The median pathologic tumor size of the parotid tumor was 3.3 cm (range, 0.2-9.4 cm). Final pathologic evaluation showed positive microscopic margins in 8 patients (27%), perineural invasion in 17 patients (57%), and facial nerve involvement in 6 patients (20%). Results: There were no isolated nodal failures. One patient developed an ipsilateral neck recurrence approximately 8 months after completion of radiation therapy. This occurred 2 months subsequent to the development of local recurrence. The 5-year actuarial rates of local (parotid) control, neck control, and overall survival were 87%, 97%, and 76%, respectively. Conclusions: Omission of the ipsilateral neck from the parotid volume does not compromise disease control for pathologically N0 patients undergoing postoperative radiation for cutaneous squamous cell carcinoma involving the parotid region. Practical implications are discussed.