Contralateral Parotid-Sparing Radiotherapy in Patients with Unilateral Squamous Cell Carcinoma of the Head and Neck: Technical Methodology and Preliminary Results

Abstract

Aims and background Radiation-induced permanent xerostomia occurs frequently in patients affected by squamous cell carcinoma of the head and neck treated by parallel opposed lateral fields. An ipsilateral technique by using co-planar multiple-field arrangement was designed to restrict treatment to the primary tumor and neck on the same side for patients with selected lateralized squamous cell carcinoma of the head and neck. Methods From November 2001 till December 2002, 30 patients affected by squamous cell carcinoma of tonsillar fossa, retro-molar trigone, alveolar ridge and oropharyngeal lateral wall were included in this investigational trial and treated with an ipsilateral multiple field technique: in detail, oblique opposed two upper half fields were planned ipsilaterally to the squamous cell carcinoma site to cover PTV1 and PTV2, whereas an anterior-lower half field was planned to encompass the lower neck node area above clavicles. On CT scans, the contralateral parotid gland was outlined as organ at risk and the contralateral upper lymph node area was contoured as volume of interest. In selected cases, convergent oblique two wedge-pair half fields were added to opposed oblique two-field technique in order to cover only PTV2: generally, in these patients, PTV1 received 1.8 Gy per fraction and PTV2 2.2 Gy per fraction up to total doses of 54 Gy and 66 Gy, respectively. Results Ten patients received radical radiotherapy, 9 patients radical alternating chemo-radiotherapy, and 11 patients adjuvant radiotherapy. At the end of treatment, unilateral confluent mucositis was recorded in 13 (43%) patients and unilateral moist skin epidermolysis in 14 (46%) patients. Six months after the end of radiotherapy, grade 0 xerostomia was recorded in 20 (67%) patients. No patient experienced grade 2+ xerostomia. At a median follow-up of 12 months, 26 (86%) patients were alive and well; 2 patients (6%) developed contralateral neck node failure, both 4 months after the end of ipsilateral radiotherapy. Conclusions These results, although preliminary, suggest that by using an ipsilateral radiotherapy technique, symptomatic xerostomia may be avoided in selected patients with lateralized squamous cell carcinoma of the head and neck without an increased short-term risk of contralateral nodal failure.