Sinonasal tumour post-operative radiotherapy guidelines: Translated from French

 

 

F. Guillemin, P. Blanchard, P. Boisselier, Y. Brahimi, V. Calugaru, A. Coutte, P. Gillon, P. Graff, X. Liem, A. Modesto, Y. Pointreau, S. Racadot, X.S. Sun, R. Bellini, N. Pham Dang, N. Saroul, J. Bourhis, J. Thariat, J. Biau, M. Lapeyre,

Proposition de délinéation des volumes cibles anatomocliniques postopératoires de la tumeur primitive des cancers du sinus maxillaire et des cavités nasales,

Cancer/Radiothérapie,

Volume 28, Issue 2,

2024,

Pages 218-227,

ISSN 1278-3218,

https://doi.org/10.1016/j.canrad.2023.12.001.

(https://www.sciencedirect.com/science/article/pii/S1278321824000313)

Key Figures from the Article :

 

 

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Introduction

Cancers of the maxillary sinus and nasal cavities account for 4% of head and neck tumors and are mainly squamous cell carcinomas, with a male-to-female ratio of 2:1 . Other histological types are rarer. Recognized carcinogens include tobacco, human papillomavirus (HPV) infection, and industrial toxic agents (glues, nickel, formaldehyde, synthetic leather, chromium, and others) .

The maxillary sinus and nasal cavities are moderately lymphophilic (a 10% risk of nodal involvement for squamous cell carcinomas, lower for adenocarcinomas) . Prophylactic nodal treatment is not recommended in principle when there is no nodal involvement for pT1 and pT2 stage tumors. It may be discussed for pT3 and pT4 stage tumors .

Prognostic factors for overall survival include the status of surgical margins, intracranial and orbital extension, invasion of the pterygomaxillary fossa, sphenoid and frontal sinuses, erosion of the cribriform plate, and dural invasion . Associated cervical lymph node involvement is also an unfavorable prognostic factor for survival . Treatment typically consists of surgical excision followed by postoperative radiotherapy. The most commonly used surgical techniques are currently endoscopic endonasal approaches, sometimes robot-assisted .

Irradiation of cancers of the maxillary sinus and nasal cavities requires mastery of the radioanatomy and natural history of these cancers. These tumors are located in an anatomical region in close proximity to many critical organs, exposing patients to risks of severe sequelae (more or less retractile fibrosis, ophthalmological complications, osteoradionecrosis, and sometimes neurological disorders). Intensity-modulated conformal radiotherapy helps reduce side effects [9–12]. It is the standard treatment for upper aerodigestive tract cancers . Particularly in non-operated or recurrent patients, proton therapy is an alternative in terms of efficacy and toxicity, though it is currently not widely available .

These techniques require rigorous definition of target volumes during planning. A method is proposed for delineating postoperative anatomoclinical target volumes of the primary tumor in cases of postoperative irradiation of maxillary sinus and nasal cavity cancers. This method relies on both geometric (as published for other head and neck sites ) and anatomical approaches. The quality of delineation of the postoperative anatomoclinical target volume of the primary tumor is crucial, as tumor recurrences are mainly localized .

It is necessary to define a high-risk volume and a low-risk volume. The postoperative anatomoclinical target volume of the primary tumor at high risk receives the highest dose, around 60 Gy (operative bed) in 30 fractions. A postoperative anatomoclinical target volume at very high risk may be discussed in cases of R1 margins in a limited area (66 Gy in 33 fractions). The postoperative anatomoclinical target volume of the primary tumor at low risk (areas of distant extension) receives a lower dose of 54 Gy with the same fractionation if a concomitant “boost” technique is used [13,14,17–19].

If irradiation of lymph node areas is required, the selection of nodal levels to be treated is not discussed in this document and is covered by separate recommendations . This document does not address the indications for external radiotherapy (which have been the subject of specific publications ) or concurrent systemic treatments, but specifies the volumes to be treated when postoperative irradiation is indicated.

 

Here is a precise, formal medical translation of the passage you provided, keeping consistent with academic radiologic and anatomic terminology suitable for publication or teaching material.

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Radioanatomical Foundations

The radioanatomical foundations have been the subject of several publications [20–22]. The images selected to illustrate this chapter are derived from diagnostic CT acquisitions and MRI sections. For didactic purposes, their number has been deliberately limited, which explains why not all structures are represented (Fig. 1).

2.1. Maxillary Sinus

The maxillary sinus lies entirely within the maxillary bone. All of its walls belong to the maxilla, except the medial wall, which is formed by the maxillary process of the inferior turbinate and the posteroinferior portion of the uncinate process of the ethmoid bone.

The maxilla itself comprises a body and four processes (zygomatic, frontal, alveolar, and palatine). Medially, the sinus communicates with the nasal cavity through the middle meatus. The superior or orbital wall of the sinus contains the infraorbital canal, transmitting the infraorbital nerve (branch V2 of the trigeminal nerve).

Posteriorly, the sinus forms the anterior boundary of the pterygopalatine and infratemporal fossae. The anterior or facial wall lies below the infraorbital foramen and above the gingivobuccal sulcus of the premolars. The roots of the first and second molars may occasionally project into or penetrate the floor of the maxillary sinus.

2.2. Nasal Cavity

The nasal cavity extends from the piriform aperture anteriorly to the choanae posteriorly, at the level of the posterior border of the hard palate. The choanae are bounded laterally by the medial plate of the pterygoid process and superiorly by the floor of the sphenoid sinus.

The floor of the nasal fossae corresponds to the hard palate (formed by the palatine bone posteriorly and the maxilla anteriorly), while the roof corresponds to the anterior cranial base. The nasal fossae are divided into right and left compartments by the nasal septum, which contains both cartilaginous and osseous components.

The perpendicular plate of the ethmoid bone constitutes the anterosuperior portion of the septum and continues posteriorly with the vomer. The septal cartilage forms the major anterior portion of the nasal septum. The roof of the nasal fossae is formed medially by the olfactory sulcus and laterally by the roof of the ethmoidal lateral masses.

The olfactory sulcus is lined with mucosa housing the olfactory receptor cells, whose axons converge to form multiple olfactory filaments that traverse the cribriform plate to reach the olfactory bulb.

The nasolacrimal duct continues inferiorly from the lacrimal sac via the lacrimonasal valve (valve of Hasner). It leaves the inferior aspect of the lacrimal sac, courses downward, and opens into the inferior meatus approximately 10–15 mm from the anterior end of the inferior turbinate. The frontal process of the maxilla forms the anterior wall of the fossa, and the lacrimal bone forms its posterior wall.

The paranasal sinuses communicate with the nasal cavity through drainage pathways whose function is sinus clearance, ensured by mucociliary transport. There is an anterior drainage pathway at the level of the middle meatus, which drains the frontal, maxillary, and anterior ethmoidal sinuses. There is also a posterior drainage pathway, located at the level of the superior meatus, which drains the posterior ethmoid. The ethmoid is thus divided into two parts according to the position of the ethmoidal cells in relation to the basal lamella of the middle turbinate, which corresponds to the site of attachment of the middle turbinate to the lamina papyracea and the skull base.

The sphenoid sinus drains through a specific ostium located medial to the superior turbinate within the sphenoethmoidal recess. The sphenopalatine foramen opens into the posterosuperior and lateral portion of the nasal cavity and constitutes the communication route between the nasal cavity and the pterygopalatine fossa.

The infratemporal fossa is located between the ascending ramus of the mandible, the pharyngeal constrictor muscles, and the lateral pterygoid plate (anterior limit: posterolateral surface of the maxilla; superior limit: greater wing of the sphenoid; posterior limit: carotid sheath and styloid process of the temporal bone). It contains the pterygoid muscles, the maxillary artery and its branches, the pterygoid venous plexus and maxillary veins, and the mandibular nerve with its branches. The boundary between the infratemporal fossa and the pterygopalatine fossa lies in a sagittal plane along the course of the maxillary nerve (V2).​

The pterygopalatine fossa is bounded anteriorly by the posterior wall of the maxillary sinus, posteriorly by the pterygoid process, superiorly by the greater wing of the sphenoid and the pterygoid process, and medially by the perpendicular plate of the palatine bone. It constitutes a crossroads of communication between the posterior part of the nasal cavity, the retropharyngeal, retrostyloid and prestyloid spaces, the parotid space, the infratemporal fossa, the orbit, and the middle cranial fossa.​

The superior wall of the pterygopalatine fossa transmits the maxillary nerve (V2), and the infraorbital artery and vein via the inferior orbital fissure. The maxillary nerve (V2) communicates with the Gasserian (trigeminal) ganglion through the foramen rotundum. The pterygopalatine fossa connects the orbit with the infratemporal fossa via the pterygomaxillary fissure and communicates superiorly with the superior orbital fissure

 

Routes of tumor spread

Tumor spread occurs contiguously via the canals and meatuses of the paranasal cavities, along mucosal surfaces, blood vessels, periosteum, and nerves (particularly the olfactory nerve, cranial nerve I, and the trigeminal nerve, cranial nerve V ). It may also occur through direct erosion of bony or cartilaginous structures.

Detailed knowledge of the anatomical relationships and zones of weakness of the nasal and paranasal cavities allows understanding of the mechanisms of tumor extension. Although the risks and patterns of spread vary between histological subtypes (for example, the neurotropism of adenoid cystic carcinomas), the gross tumor target volumes remain broadly similar.

 3.1. Maxillary sinus

The routes of tumor spread depend on the site of origin within the sinus, but in practice the entire sinus is often involved because it is rare to diagnose very limited lesions. Anterior extension proceeds toward the ipsilateral nasolacrimal duct, the anterior wall of the maxillary sinus, then the cheek, the gingivobuccal sulcus, and the maxillary division of the trigeminal nerve (V2).

Posterior extension progresses toward the posterior wall (infratemporal surface of the maxilla), then into the infratemporal and pterygopalatine fossae. Posterior spread also occurs toward the ipsilateral pterygoid process (arising from the inferior surface of the sphenoid), the nasopharynx medially, and the sphenoid sinus. In some cases, tumor may reach the foramen ovale, which connects the middle cranial fossa with the infratemporal fossa and transmits the mandibular nerve (V3). Posterior lesions erode the posterolateral wall and invade the infratemporal fossa or the pterygopalatine fossa.

Superiorly, extension is directed toward the inferior (and possibly medial) orbital wall, the inferior orbital fissure, the foramen rotundum, and then the Gasserian (trigeminal) ganglion. Superior spread may also involve the lamina papyracea, then the ethmoid, and ultimately the pterygopalatine fossa and infraorbital fissure.

In cases of orbital extension, tumor may spread toward the cavernous sinus via the superior orbital fissure (the opening between the lesser and greater wings of the sphenoid) and the optic canal through which the optic nerve passes. Through this route, the ocular motor nerves (III: oculomotor, IV: trochlear, V1: ophthalmic division of the trigeminal nerve, VI: abducens), the ophthalmic veins, the sympathetic nerve fibers, and the orbital branch of the middle meningeal artery pass between the middle cranial fossa and the orbital cavity.

Medial extension proceeds into the ipsilateral nasal cavity and then into the nasal septum, nasal bones, and anteriorly into the nasal vestibule. Lateral spread occurs via the buccal fat pad and the infratemporal fossa. Inferior extension involves the hard palate and the alveolar ridge. Lesions in contact with the anterolateral and inferior aspects tend to infiltrate through the inferolateral wall and may enter the oral cavity by eroding the gingival portion of the maxilla, leading to submucosal deformity of the hard palate, sometimes associated with dental loosening or loss.

3.2. Nasal cavity

Tumors of the nasal cavities tend to destroy the nasal septum and may extend anteriorly into the nasal vestibule and then the overlying skin, the upper lip, and superiorly the nasal bones. Posterior extension, when the posterior half of the cavity is involved, proceeds toward the nasopharynx through the choanae (via submucosal spread), then superiorly into the sphenoid sinus (located posterior to the ethmoid) and laterally into the pterygoid processes.

Superior extension proceeds into the ethmoid, laterally into the pterygopalatine fossa via the sphenopalatine foramen, the foramen rotundum, and the lamina papyracea, and may reach the inferior orbital wall via the maxillary sinus more anteriorly. Inferior extension involves the hard palate and the alveolar ridge. Lateral extension proceeds anteriorly toward the cheek and the nasolacrimal pathway, the intersinusonasal wall, the ipsilateral maxillary sinus via the middle meatus, and posteriorly toward the pterygoid processes.

Proposed delineation of irradiation volumes

Before starting delineation of the postoperative anatomoclinical target volumes of the primary tumour, it is necessary to register the preoperative imaging studies (facial MRI and contrast-enhanced CT) with the planning CT scan (performed using an iterative metal artefact reduction reconstruction, IMAR) in order to limit artefacts and thereby increase the precision of delineation. When available, PET‑CT can also help in delineating the gross tumour volume. The registration is rigid and bone-based, but must nevertheless take into account any anatomical changes related to reconstruction.

The interval between preoperative imaging and surgery must be considered in order to estimate as accurately as possible the size of the initial gross tumour volume at the time of registration. A postoperative MRI with image registration may be performed and is essential if there is any doubt about postoperative residual disease on the contrast-enhanced planning CT. As far as possible, a bite spacer should be used during the planning CT and during treatment sessions in order to limit the dose delivered to the tongue, lower lip, and mandible. However, the bite spacer may sometimes cause difficulties with image registration during treatment sessions.

Based on the registered images, delineation of the preoperative gross tumour volume is then performed (Fig. 2). The operative and pathological reports allow this preoperative gross tumour volume to be expanded if certain structures are described as involved, which may occur when the interval between diagnostic imaging and surgery is long (see the generated image above).

 

The postoperative anatomoclinical target volume of the primary tumour at low risk comprises a set of structures or anatomical compartments contiguous with the initial gross tumour, to treat zones of microscopic peritumoral infiltration at distance. It varies according to anatomical barriers, spaces and anatomical compartments (fissures, meatuses, canals) and zones of preferential spread such as perineural and perivascular infiltrations. In case of doubt about any extension, it is preferable to expand the volumes to limit the risk of recurrence.

To obtain this postoperative anatomoclinical target volume of the primary tumour at low risk (54 Gy), extensions may initially be defined by applying a geometric concept. A geometric expansion of 10 to 15 mm around the registered preoperative gross tumour volume is performed, which allows obtaining an extended volume. This is then reduced by removing air and conforming to anatomical barriers. To properly visualize the mucosae or fine structures that disappear on mediastinal window settings, a parenchymal window setting of the scanner is necessary (see the generated image above). In a second step, the postoperative anatomoclinical target volume of the primary tumour at low risk obtained is manually extended to include all routes of extension at risk according to an anatomical concept (Table 1)

 

Limits	Structures anatomiques selon la localisation tumorale
	Maxillary Sinus	Nasal Cavities
Anterior Limit	Ipsilateral nasolacrimal pathway, anterior wall of the maxillary sinus, then ipsilateral cheek, gingivobuccal sulcus, and maxillary division of trigeminal nerve (V2)	In case of involvement of the anterior half of the nasal fossae: nasal vestibule then skin and cheek, nasal bones superiorly, maxillary division of trigeminal nerve (V2) in its anterior portion
Posterior Limit	Posterior wall, infratemporal and pterygopalatine fossae, ipsilateral foramen ovale, ipsilateral pterygoid process, ipsilateral sphenoid sinus superiorly and ipsilateral nasopharynx medially, foramen rotundum	In case of involvement of the posterior half: nasopharynx then clivus for large tumors, sphenoid sinus superiorly, and pterygoid processes laterally
Superior Limit	Inferior orbital wall (with or without lamina papyracea), inferior orbital fissure, foramen rotundum, ipsilateral Gasserian ganglion, cavernous sinus in case of intraorbital involvement via superior orbital fissure, optic canal	Ethmoid, pterygopalatine fossa laterally via sphenopalatine foramen, foramen rotundum, lamina papyracea (with or without inferior orbital wall via maxillary sinus more anteriorly)
Inferior Limit	Hard palate and alveolar ridge	Hard palate, alveolar ridge
Medial Limit	Ipsilateral nasal cavity then nasal septum, nasal bones, and nasal vestibule anteriorly	[Not specified in original table]
Lateral Limit	Buccal fat space, infratemporal fossa	Nasolacrimal pathways, intersinusonasal walls, and ipsilateral maxillary sinus via middle meatus, pterygoid processes

 

In a third step, to obtain the postoperative anatomoclinical target volume of the primary tumour at high risk (60–66 Gy), a geometric expansion of 5 to 10 mm is applied around the preoperative gross tumour volume and then resized within the postoperative anatomoclinical target volume of the primary tumour at low risk. It may also be extended to specific areas estimated to be at high risk within the postoperative anatomoclinical target volume of the primary tumour at low risk (using Boolean operators if necessary) according to pathological analysis and zones of anatomical weakness. In case of reconstruction with a flap, the postoperative anatomoclinical target volumes of the primary tumour must encompass at minimum the interface between the flap and healthy tissues, as the risk of recurrence is maximal at the junction of native tissues and flap.[1]

 

In case of R1 margins confirmed by the surgeon or specified in the operative report (zones of adherence, resection in contact with tumour) and in case of a suspicious zone without a true mass on postoperative MRI, a postoperative anatomoclinical target volume of the primary tumour at very high risk (66 Gy) may be discussed. This will consist of the preoperative gross tumour volume limited to the R1 zone expanded by a 5 mm margin and included within the postoperative anatomoclinical target volume of the primary tumour at high risk. Finally, in case of postoperative gross residual disease (R2), a dose of 70 Gy may be proposed.[1]

 

The postoperative anatomoclinical target volumes of the primary tumour for postoperative delineation of maxillary sinus and nasal cavity cancers are presented in Fig. 3.

 

Organs at risk are delineated on the planning CT acquisitions. MRI assistance is necessary (brainstem, optic nerves, and optic chiasm) and the dose constraints for organs at risk comply with the constraints defined in the Recommendations for the Management of Patients with Cancer by Radiotherapy (RecoRadTM) [25–27]. Nevertheless, in certain cases of tumour extending in contact with an optic nerve, it is sometimes impossible to respect the dose constraints and the planned dose may exceed the dose threshold on the optic nerve. In such cases, validation of the treatment plan must be performed after informing the patient and obtaining consent regarding the risk of unilateral blindness and the benefit–risk balance of treatment. Doses to contralateral structures (optic nerve, chiasm, cornea, lens, retina, lacrimal glands) must be reduced as much as possible to preserve visual function and limit the risk of complications.

These complex dosimetric situations may warrant an indication for sequential intensity-modulated radiotherapy followed by a dose boost under stereotactic conditions with non-coplanar beams, particularly in cases of proximity between the planned target volume and optical structures.

 

Conclusion

The selectivity of infraclinical postoperative irradiation volumes for maxillary sinus and nasal cavity cancers is complex. Based on knowledge of radioanatomy and the routes of tumour spread, a procedure is proposed to assist in the delineation of postoperative anatomoclinical target volumes of the primary tumour. This approach relies on the registration of the planning CT with preoperative imaging to reposition the initial gross tumour volume and the creation of margins around it extended to at-risk zones according to anatomical concept.