A contouring guide for head and neck cancers with perineural invasion

Purpose Perineural invasion (PNI) is a frequent pathological finding in head and neck cancers. When adjuvant radiation to cranial nerves at risk in head and neck cancers with PNI is considered, there is a need for consensus on which nerves are at risk and how to contour these nerves. This contouring guide attempts to address this need. Methods and materials Representative patient diagnostic computed tomographic (CT) scans with contrast of the neck were used to create example contours. The cranial nerves V2, V3, VII, and XII, and sample primary tumor sites were initially delineated using the Varian Eclipse planning system by 5 radiation oncologists. All of the images were then reviewed with a diagnostic radiologist to establish consensus for delineating the cranial nerves. Results We provided detailed contouring and planning guidelines on a CT atlas, with figures to help illustrate internerve connections, based on clinical experience, literature-based patterns of failure, and established anatomic connections between cranial nerves. Tumor bed, cranial nerve, and elective target volumes are depicted. Conclusions These planning guidelines and atlas provide anatomic, clinical, and technical recommendations for guiding radiation oncologists in the planning and delivery of intensity modulated radiation therapy for head and neck cancer with PNI.