Principles and Techniques of Radiotherapy and Chemotherapy for Nasal Cavity and Paranasal Sinus Tumors
Sinonasal malignancies are relatively rare tumors of the head and neck accounting for less than 1% of all malignancies and ~3% of upper respiratory tract tumors.1
Tumors originating within the nasal vestibule, nasal fossa, and paranasal sinuses each have a unique natural history and biological behavior. The therapeutic principles and techniques also vary for each type of tumor, although for any tumor type special consideration is always given to organ preservation, organ function, and overall cosmesis. A multidisciplinary team approach involving experts in head and neck cancer surgery, radiotherapy, chemotherapy, imaging, and pathology is best suited for managing cases of disease in this region to provide patients with the best chance of cure and optimal quality of life. Primary and adjuvant radiotherapy have essential roles in the overall treatment strategy for tumors in this complex anatomical location. This chapter focuses primarily on the principles and techniques of radiotherapy and chemotherapy for carcinomas of the nasal cavity and paranasal sinuses.
Tumors of the Nasal Cavity
Treatment Principles
Nasal Vestibule Tumors
The definitive treatment for nasal vestibule tumors is either surgery, primary radiotherapy, or—when indicated because of tumor size or positive surgical findings—surgery followed by adjuvant radiation therapy. The role of systemic chemotherapy has not been established for tumors of this type. For small superficial tumors, standard treatment approaches are surgery or primary radiotherapy, delivered as external beam radiotherapy, brachytherapy, or a combination of the two. Either approach (surgery or primary radiotherapy) can yield high control rates with excellent cosmesis. Small invasive tumors are treated with either surgery or primary radiotherapy. Adjuvant radiation is indicated in cases involving positive surgical margins, positive lymph nodes, or perineural invasion. For large invasive tumors, the combination of surgery and radiotherapy—with radiotherapy given either before or after surgery—is the mainstay of treatment. Older patients and patients with poor performance status may be treated with radiotherapy alone.
The presence of cartilage invasion should not be considered a contraindication for radiotherapy because the risk of necrosis is low after fractionated radiotherapy.2
Patients with large defects after surgery and adjuvant radiation for large invasive tumors can be fitted with custom-made nasal prostheses by experienced prosthodontists.
Several retrospective studies of the use of radiotherapy for nasal vestibule tumors3–11 suggest that either brachytherapy or external beam radiotherapy can produce cure rates approximating 90% for patients with small lesions (<2 cm in diameter) (Table 20.1). For lesions 2 to 4 cm in diameter, external beam radiotherapy can control 70 to 80% of tumors. Although nodal spread of disease is relatively rare for lesions smaller than 2 cm, up to 40% of patients with larger primary tumors have metastases to the cervical nodes at presentation. With the use of appropriate radiation techniques and fractionation schedules (described further below), severe and late complications after radiation therapy are uncommon (Table 20.1).
Nasal Fossa Tumors
Either primary radiotherapy or surgery for early-stage nasal fossa lesions can produce similarly high control rates. The size and location of the tumor as well as the anticipated cosmetic outcome generally guides the choice of treatment. Surgery is the mainstay of treatment for posterior septum lesions or locally advanced lesions. Primary radiotherapy, given as brachytherapy, is appropriate for small anterior-inferior septal lesions; external beam radiotherapy may produce the best cosmetic result for lateral wall lesions extending to the nasal ala.
Documentation of treatment outcomes for nasal fossa tumors comes mostly from retrospective studies.12–15 Locoregional control rates range from 60 to 85%, and the rate of isolated regional recurrence in patients who did not receive elective nodal irradiation is ~5%. The most common complications after radiotherapy were soft tissue necrosis, visual impairment, and nasal stenosis (Table 20.2). Ang et al reported better primary disease control and survival rates for patients with tumors located in the septum (86%) versus patients with tumors on the lateral wall or floor of the nasal fossa (68%).12 In that study, patients with nasal septum carcinomas who underwent elective nodal irradiation had no nodal relapses, whereas 2 of 8 patients who did not undergo nodal irradiation experienced recurrence in the ipsilateral subdigastric nodes. Distant metastasis was more common among patients with lateral wall and floor disease, and ultimately survival rates were best among patients with nasal septum tumors. However, Badid et al13 and Hawkins et al15 found no differences in results for tumors at various sites within the nasal cavity. Results of treatment for early-stage tumors are equally good after radiotherapy or surgery; Bosch et al. found that the T1 lesions were well controlled with either surgery or radiotherapy and were associated with a 5-year overall survival rate of 91%.14
Esthesioneuroblastoma (Olfactory Neuroblastoma)
Single-modality therapy with either primary radiotherapy or surgery can produce locoregional control rates exceeding 90% when esthesioneuroblastoma lesions are confined to the nasal cavity (i.e., stage A).16 Single-modality therapy has also been used for lesions involving the nasal cavity and one or more paranasal sinuses (stage B), as has surgery followed by adjuvant radiation therapy. However, the optimal therapy for stage B lesions is not clear because of the heterogeneity of these tumors. Disease that extends beyond the nasal cavity and paranasal sinuses (stage C) seems to be best treated with a combination of surgery and radiotherapy. Chemotherapy may have a role in the management of stage C disease. Elective nodal irradiation is not generally recommended because the incidence of nodal relapse is less than 15%. Distant metastasis is uncommon (10%) even among patients presenting with locally advanced disease. At this time, the role of systemic therapy for esthesioneuroblastoma is considered investigational; moreover, prospective studies to identify the optimal therapy are unlikely because of the rarity of this disease.
Radiotherapy Techniques17
Nasal Vestibule Tumors
External Beam Radiotherapy
Thin superficial nasal vestibule lesions can be treated with either orthovoltage X-rays or electrons with skin bolus; thicker lesions are generally treated with electrons. For definitive therapy, well-differentiated tumors that are circumscribed and up to 1.5 cm in diameter are generally treated to a dose of 66 to 70 Gy with a 1- to 2-cm margin, with a small treatment-field reduction after 50 Gy to boost the dose to the gross disease. Tumors larger than 1.5 cm and poorly differentiated are treated with a wider 2- to 3-cm margin, with irradiation of the bilateral facial nodes, submandibular nodes, and subdigastric nodes. For patients presenting with palpable neck adenopathy, the entire neck is treated with at least a subclinical dose of 50 Gy, and the gross disease plus a 1- to 2-cm margin is then treated with an additional 16 to 20 Gy.
For the larger nasal vestibule lesions, the lower half of the nose and the upper lip are treated with an anterior appositional field using 20-MeV electrons and 6-MV photons weighted 4 to 1. The right and left facial lymphatics are irradiated with anterior appositional fields using ~15-degree gantry rotation to the respective side with 6-MeV electron fields. The medial border is matched to the lateral border of the anterior primary field. The anterior border extends down from the oral commissure to the middle of the horizontal ramus of the mandible, whereas the posterior border extends from the upper edge of the anterior field to just above the angle of the mandible. The inferior border splits the horizontal ramus of the mandible and is matched to the upper neck field. The upper neck nodes are treated with parallel-opposed lateral photon fields. The primary tumor is treated to 60 Gy (at 90%) in 30 fractions, and the electively treated facial and upper neck nodes are treated to 50 Gy in 25 fractions.
When postoperative radiotherapy is indicated for close or positive surgical margins, perineural invasion, or tumors larger than 5 cm in diameter, the operative bed plus a 1- to 1.5-cm margin is treated to a dose of 60 to 66 Gy. Postoperative radiation doses to the neck depend on whether the neck was dissected and the presence of nodal disease: if dissection reveals positive lymph nodes, the dose is 60 Gy; if dissection reveals no evidence of nodal disease, the dose is 56 Gy; and if dissection was not done and nodal disease is not evident, the dose is 50 Gy, all delivered in 2-Gy fractions.
Patient Setup
For external beam radiotherapy to nasal vestibule tumors, the patient is positioned supine, with the neck slightly flexed so as to align the anterior surface of the maxilla perpendicular to the couch of the treatment table. The patient is immobilized with a customized mask, and an anterior appositional field is generally appropriate. For treatment of the primary tumor, skin collimation is used to minimize scattering of radiation to the eye and to reduce the beam penumbra. To avoid heterogeneity due to the oblique incidence and surface irregularity, customized beeswax material is commonly used to generate a flat surface contour for electrons. To reduce heterogeneities and avoid dose perturbations from air cavities when electron beams are used, tissue-equivalent material or “bolus” is used to fill the nares. An intraoral Cerrobend (Wood′s metal)-containing stent is commonly used to displace the tongue posteriorly and to partially shield the upper alveolar ridge from the radiation.
The right and left facial lymphatics are irradiated with anterior appositional fields using ~15-degree gantry rotation to the respective side. Each field abuts both the appositional primary lesion portal and the upper neck fields. To reduce the risk of excessive heterogeneity at the abutment sites, the dose is feathered by incorporated junction shifts twice during the course of treatment. The submandibular and subdigastric nodes are treated with lateral parallel-opposed photon fields, and when nodes are involved, the middle and low neck nodes are treated with an anterior field matched to the lateral upper neck field.
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