{"id":13808,"date":"2026-03-11T22:50:14","date_gmt":"2026-03-12T01:50:14","guid":{"rendered":"https:\/\/rtmedical.com.br\/tmp-en-1773280211782\/"},"modified":"2026-04-04T18:06:23","modified_gmt":"2026-04-04T21:06:23","slug":"nasal-cavity-paranasal-sinus-tumors","status":"publish","type":"post","link":"https:\/\/rtmedical.com.br\/en\/nasal-cavity-paranasal-sinus-tumors\/","title":{"rendered":"Nasal Cavity and Paranasal Sinus Tumors"},"content":{"rendered":"

Anatomy and Patterns of Spread in Sinonasal Tumors<\/h2>\n

Sinonasal tumors present a unique challenge in radiation planning. The nasal cavity and paranasal sinuses are interconnected through multiple ostia and separated only by thin septa \u2014 facilitating local extension into adjacent cavities. This interconnected anatomy demands meticulous attention during target volume delineation.<\/p>\n

\"Axial
Postoperative T4aN0M0 SNUC case with CTV60 (orange) covering the surgical bed and CTV54 (pink) covering bilateral elective nodal volumes. Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n

Histologic diversity is striking. Squamous cell carcinoma, minor salivary gland adenocarcinoma, adenoid cystic carcinoma, esthesioneuroblastoma (ENB), sinonasal undifferentiated carcinoma (SNUC), small cell neuroendocrine carcinoma (SNEC), melanomas, and NUT midline carcinoma \u2014 each subtype exhibits distinct biological behavior and requires specific adaptations in target volume design.<\/p>\n

Several spread patterns deserve particular attention. ENB, SNUC, and SNEC arise in the superior nasal cavity and readily invade the cribriform plate into the anterior cranial fossa. These regions must be encompassed in the target volume. Maxillary sinus cancers, on the other hand, may invade the nasal cavity through the porous medial wall, the maxillary gingiva through the lateral antral wall, the infratemporal or pterygopalatine fossa via posterior spread, or the orbit by direct superior extension or through the ethmoid sinuses.<\/p>\n

Perineural invasion is another critical consideration. When cranial nerve involvement is present, covering the affected nerve back to the skull base is essential. Microscopic skip metastases along nerves are common, and recurrences along this pathway can be extremely difficult to salvage. For adenoid cystic carcinomas specifically, cranial nerve coverage is strongly recommended even without pathologically confirmed perineural invasion.<\/p>\n

Target Volumes and Prescription Doses<\/h2>\n

Target volume delineation in sinonasal tumors follows well-defined principles but requires flexibility given the proximity to critical structures. The tables below summarize definitions and recommended dose levels.<\/p>\n

Gross disease volumes<\/h3>\n\n\n\n\n\n\n\n
Volume<\/th>\nDefinition<\/th>\nDose<\/th>\n<\/tr>\n<\/thead>\n
GTV70<\/sub><\/strong><\/td>\nAll gross disease on physical examination and imaging (CT and MRI). PET helps further define tumor extent. MRI identifies perineural invasion that may be occult on PET<\/td>\n70 Gy (1.8\u20132 Gy\/fraction)<\/td>\n<\/tr>\n
CTV70<\/sub><\/strong><\/td>\nUsually identical to GTV70<\/sub>. A 3\u20135 mm margin may be added for uncertainty in primary tumor delineation. Can be as small as 0 mm near critical structures \u2014 GTV may equal CTV<\/td>\n70 Gy<\/td>\n<\/tr>\n
PTV70<\/sub><\/strong><\/td>\nCTV70<\/sub> + 3\u20135 mm depending on setup uncertainty. Reduced to 1 mm near brainstem and optic chiasm<\/td>\n70 Gy<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Source: Target Volume Delineation and Field Setup, 2nd Edition (Table 7.1)<\/em><\/p>\n

High- and low-risk subclinical volumes<\/h3>\n\n\n\n\n\n\n\n\n
Volume<\/th>\nDefinition<\/th>\n<\/tr>\n<\/thead>\n
CTV60\u201366<\/sub><\/strong><\/td>\nEncompasses regions at high risk for microscopic disease. Postoperative: includes resection bed, areas of nodal extension, and all initial preoperative disease sites. Consider coverage of the entire postoperative bed and flap. Definitive: 5\u201310 mm expansion on the primary tumor covering the relevant anatomic subsite, respecting anatomic boundaries. CTV66<\/sub> for positive margins or extranodal extension (6 Gy in 3 sequential fractions)<\/td>\n<\/tr>\n
CTV50\u201354<\/sub><\/strong><\/td>\nLow-risk subclinical regions including non-violated neck or prophylactic cranial nerve coverage<\/td>\n<\/tr>\n
PTV60\u201366<\/sub><\/strong><\/td>\nCTV60\u201366<\/sub> + 3\u20135 mm. Can be reduced to 1 mm near critical normal structures<\/td>\n<\/tr>\n
PTV50\u201354<\/sub><\/strong><\/td>\nCTV50\u201354<\/sub> + 3\u20135 mm depending on setup uncertainty and image guidance technique<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Source: Target Volume Delineation and Field Setup, 2nd Edition (Table 7.2)<\/em><\/p>\n

In practice, the proximity to structures like the brainstem, optic chiasm, and optic nerves often forces PTV margins down to 1 mm at these interfaces. This margin compression is acceptable provided high-quality daily image guidance is in place. For a comprehensive overview of how these strategies fit into the broader planning framework, see our complete guide on target volume delineation and field setup<\/a>.<\/p>\n

Diagnostic Workup for Target Delineation<\/h2>\n

Accurate target volume definition begins with a thorough diagnostic workup. A detailed review of the preoperative history, neurologic examination emphasizing cranial nerve function, pre- and postoperative imaging, operative report, and pathology report \u2014 all are needed to properly define volumes.<\/p>\n

\"Axial
T4bN1M0 SCC of the left maxillary sinus with GTV70 (red) and CTV50 (pink) covering the orbital floor, infraorbital fissure, foramen rotundum, pterygopalatine fossa, infratemporal fossa, and masticator space. Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n

Beyond fiberoptic endoscopy, high-quality diagnostic imaging is critical for tumor localization. Each modality plays a specific role:<\/p>\n

High-resolution CT<\/strong> of the paranasal sinuses with IV contrast and thin 1\u20132 mm slices best visualizes early cortical bone erosion. Thin-slice MRI<\/strong> with IV contrast and fat-suppressed sequences is superior for assessing soft tissue spread, intracranial extension, perineural invasion, and involvement of cranial nerve foramina and canals. PET\/CT<\/strong> complements staging by identifying suspicious lymph nodes and metastatic disease.<\/p>\n

Simulation and Daily Localization<\/h2>\n

The patient should be simulated supine with a head rest, neck extended, using a five-point customized Aquaplast mask immobilizing the head, neck, and shoulders. A shoulder pull board can lower the shoulders out of the beam path.<\/p>\n

A bite block pushes the tongue inferiorly away from the high-dose nasopharynx. For patients with many metal fillings, a custom mouthguard absorbs electron scatter and mitigates treatment-related mucositis. CT simulation should use slices of 3 mm or less with IV contrast, covering the entire vertex through the carina. The isocenter is typically placed at the arytenoids.<\/p>\n

For postoperative cases, placing radiopaque markers on surgical scars helps delineate the tumor bed. Daily image guidance \u2014 ideally cone beam CT aligned to bone \u2014 is essential. Daily kV imaging with weekly cone beam CTs is also adequate.<\/p>\n

Subsite-Specific Delineation and Treatment Planning<\/h2>\n

The GTV should be delineated using all relevant clinical information from endoscopy, CT, MRI, and PET. The high-risk CTV must encompass all initial disease sites and potential regions of subclinical spread. All preoperative scans must be evaluated to ensure the initial tumor volume is covered.<\/p>\n

\"Axial
Anterior nasal cavity SCC with CTV54 (green), CTV60 (orange), and CTV66 (red) covering extranodal extension areas. Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n

MRI should be used in all cases unless medically contraindicated. Adenoid cystic carcinomas are highly neurotropic, so target volumes must encompass afferent and efferent local nerves to the skull base. ENB arises in the superior nasal cavity and tends to invade the cribriform plate and anterior cranial fossa early.<\/p>\n

The table below details subsite-specific anatomical considerations for primary CTV delineation.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Subsite<\/th>\nDirection<\/th>\nDelineation Considerations<\/th>\n<\/tr>\n<\/thead>\n
Maxillary sinus (SCC)<\/strong><\/td>\nSuperior<\/td>\nOrbital floor\/skull base. Coronal MRI useful for orbital floor involvement. Intracranial extension: consider 5 mm dural margin<\/td>\n<\/tr>\n
Inferior<\/td>\nHard palate with at least 10 mm margin around initial gross disease<\/td>\n<\/tr>\n
Medial<\/td>\nNasal septum for lateralized cases. Extension beyond septum: consider entire nasal cavity coverage<\/td>\n<\/tr>\n
Lateral<\/td>\nInfratemporal fossa including masticator space. Lateral extension: consider coverage along temporalis muscle<\/td>\n<\/tr>\n
Posterior<\/td>\nPterygopalatine fossa and skull base, including infraorbital fissure. Posterior involvement: cover CN V2\/V3 courses to Meckel’s cave<\/td>\n<\/tr>\n
Nerves<\/td>\nBranches of CN V2, infraorbital nerve, and greater palatine nerves<\/td>\n<\/tr>\n
Nasal cavity (SCC, ENB, SNUC, SNEC, melanoma)<\/strong><\/td>\nSuperior<\/td>\nCribriform plate if intact; otherwise include dural graft. 5 mm dural margin when cribriform plate is involved or gross intracranial extension<\/td>\n<\/tr>\n
Inferior<\/td>\nHard palate<\/td>\n<\/tr>\n
Medial<\/td>\nInclude the entire nasal cavity<\/td>\n<\/tr>\n
Lateral<\/td>\nMedial border of ipsilateral maxillary sinus for localized cases<\/td>\n<\/tr>\n
Posterior<\/td>\nPterygoid plates, pterygopalatine fossa, ethmoid sinus, and sphenoid sinus<\/td>\n<\/tr>\n
Nerves<\/td>\nBranches of CN I, CN V1, and CN V2 including nasociliary and nasopalatine nerves<\/td>\n<\/tr>\n
Ethmoid sinus<\/strong><\/td>\nSuperior<\/td>\nSame as nasal cavity<\/td>\n<\/tr>\n
Inferior<\/td>\n10 mm margin on initial tumor extent. Early tumors: inferior turbinate acceptable. Advanced tumors: include hard palate<\/td>\n<\/tr>\n
Medial\/Lateral<\/td>\nNasal cavity, ethmoid sinuses, and ipsilateral maxillary sinus. Lamina papyracea breach: include medial rectus<\/td>\n<\/tr>\n
Posterior<\/td>\nSkull base and sphenoid sinus. Retropharyngeal nodes if nasopharyngeal involvement or N1 disease<\/td>\n<\/tr>\n
Nerves<\/td>\nBranches of CN V1 and CN V2. Parasympathetic innervation via Vidian nerve<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Source: Target Volume Delineation and Field Setup, 2nd Edition (Table 7.3)<\/em><\/p>\n

Special situations warrant attention. SNEC carries a high risk of metastatic disease and may be treated with standard fractionation or 45 Gy in 30 fractions given BID; elective nodal coverage may be omitted. Nasal mucosal melanoma also carries high metastatic risk \u2014 large tumors receive standard fractionation, while small tumors may be treated with 30\u201336 Gy in 6 Gy fractions given twice weekly to the primary site only.<\/p>\n

Elective Nodal Irradiation and Planning Approach<\/h2>\n

Elective neck irradiation should be considered on a case-by-case basis. It makes particular sense for ENB and advanced squamous cell carcinoma, especially when arising from the maxillary sinus or when areas with extensive lymphatic supply are involved \u2014 nasopharynx, mucosa, skin, cheek, anterior nose, maxillary gingiva, or alveolar ridge.<\/p>\n

\"Axial
T3N0M0 adenoid cystic carcinoma of the maxillary sinus with GTV70 (red) and CTV60 (orange) covering the superior and inferior orbital fissures, foramen rotundum, pterygopalatine fossa, and Vidian canal. Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n

Regional nodal drainage follows predictable patterns: retropharyngeal nodes and levels IB\u2013IV. Level V should be included when the nasopharynx is involved. Facial node coverage should be considered for nasal cavity tumors. Most primary tumors are midline structures, justifying bilateral nodal irradiation. The exception is maxillary sinus cancers, which receive unilateral nodal treatment.<\/p>\n

The surgical approach \u2014 midface degloving, lateral rhinotomy, craniofacial resection, or endoscopic resection \u2014 directly influences field design. When craniofacial resection has been performed, the frontal graft must be included in the target volume. Surgical fiducial markers help delineate the tumor bed.<\/p>\n

For planning, the Memorial Sloan-Kettering Cancer Center team favors a sequential cone-down approach<\/strong>. An initial plan over 30 fractions uses dose-painting to deliver 54 Gy (1.8 Gy\/fraction) to low-risk subclinical regions and 60 Gy (2 Gy\/fraction) to high-risk subclinical regions. A subsequent cone-down plan over 5 fractions delivers an additional 10 Gy to gross disease only, for a total of 70 Gy in 35 fractions.<\/p>\n

\"Axial
Cervical level delineation in the same anterior nasal cavity SCC case, showing CTV60 (orange) and CTV66 (red) at extranodal extension areas. Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n

Sinonasal tumors demand from the radiation oncologist a deep understanding of skull base anatomy, cranial nerve foramina and canals, and local and regional spread pathways. The fusion of CT and MRI, careful operative report review, and PET\/CT staging form the foundation for quality delineation. Each histology has its own particularities \u2014 from the neurotropism of adenoid cystic carcinoma to the aggressive cribriform invasion pattern of SNUC. Attention to these details separates adequate planning from truly effective planning.<\/p>\n","protected":false},"excerpt":{"rendered":"

Target volume delineation for sinonasal tumors: anatomy, doses, subsite-specific considerations, and sequential cone-down planning approach.<\/p>\n","protected":false},"author":1,"featured_media":16415,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"ngg_post_thumbnail":0,"fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[266,265,99],"tags":[],"class_list":{"0":"post-13808","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-delineamento-cabeca-pescoco","8":"category-delineamento-volumes","9":"category-radiotherapy"},"aioseo_notices":[],"rt_seo":{"title":"Nasal Cavity & Paranasal Sinus RT Delineation","description":"Target volume delineation for nasal cavity and paranasal sinus tumors. GTV\/CTV for maxillary, ethmoid, and sphenoid sinus radiotherapy.","canonical":"","og_image":"","robots":"default","schema_type":"MedicalWebPage","include_in_llms":false,"llms_label":"","llms_summary":"","faq_items":[{"q":"How are paranasal sinus tumors delineated for RT?","a":"Paranasal sinus tumors require MRI-CT fusion for accurate GTV definition due to complex bony anatomy and soft tissue extension. The CTV must account for perineural spread along cranial nerves and potential extension into the orbit, anterior cranial fossa, and pterygopalatine fossa."},{"q":"What is the role of MRI in sinonasal tumor delineation?","a":"MRI distinguishes tumor from retained secretions and inflammatory changes that appear similar on CT. T2-weighted and contrast-enhanced sequences are critical for defining the true extent of disease, especially for skull base and orbital involvement."},{"q":"What are the critical OARs in sinonasal RT?","a":"Optic nerves, chiasm, eyes, lacrimal glands, and brain are the primary OARs. Proton therapy or IMRT is often required to achieve adequate target coverage while respecting dose constraints for these structures, particularly when disease abuts the optic apparatus."}],"video":[],"gtin":"","mpn":"","brand":"","aggregate_rating":[]},"_links":{"self":[{"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/posts\/13808\/"}],"collection":[{"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/posts\/"}],"about":[{"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/types\/post\/"}],"author":[{"embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/users\/1\/"}],"replies":[{"embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/comments\/?post=13808"}],"version-history":[{"count":2,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/posts\/13808\/revisions\/"}],"predecessor-version":[{"id":16473,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/posts\/13808\/revisions\/16473\/"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/media\/16415\/"}],"wp:attachment":[{"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/media\/?parent=13808"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/categories\/?post=13808"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/tags\/?post=13808"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}