Adjuvant Intensity Modulated Radiation Therapy With a Pedicled Flap Reconstruction in Oral Cavity Squamous Cell Carcinomas: Implications on Target Delineation.

Objectives: To address controversies regarding target volume delineation for adjuvant intensity-modulated radiation therapy for oral cavity squamous cell carcinoma with pedicled flap reconstruction and elective nodal irradiation (ENI).

Materials and methods: During target volume delineation, the primary tumor bed was the pre-surgical gross tumor volume with an additional isotropic margin of 5-10 mm. Additionally, the flap and body tissue junction were given a margin of 5-10 mm (if not already given). An effort was not made to trace the flap for inclusion in the clinical target volume (CTV), except when it traversed through the involved nodal regions. Contralateral ENI was carried out only in tumors crossing the midline when there was a heavy nodal burden at Ia/Ib.

Results: In the 143 patients analyzed, the most common sub-site was buccal mucosa (78, 54.5%). Contralateral ENI was done in 63 patients (36 Tongue, 23 Buccoalveolar). The median follow-up of surviving patients was 24 months. The 2-year Locoregional Control, Disease-Free Survival, and Overall Survival were 77.4%, 64.5%, and 79% respectively. Overall, there were 55 (38.5%) recurrences, of which 35 (24.5%) were either local, regional, or combined locoregional failures, 13 (9.1%) were distant failures alone, and 7 (4.9%) had both locoregional and distant failures. The elective nodal regions had 3 (2.1%) contralateral nodal failures.

Conclusion: The entire flap need not be intentionally covered in the target volume. Contralateral ENI should be considered only for patients with heavy nodal burden at ipsilateral level Ia/Ib, in tumors crossing the midline, or in tumors having a high propensity for contralateral lymph nodal involvement.