xRead - Nasal Obstruction (September 2024) Full Articles

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ment, with local recurrence being the main reason. Due to the rarity of these tumors and histological variability, there is a paucity of studies specifically addressing salvage treatment for the different types of SNMs. Although the evidence available is limited and of low quality, it does suggest that salvage treatment may improve the outcome of patients with locoregional recurrences. When possible, salvage surgery, with the aim of obtaining negative sur gical margins, and adjuvant RT (including reirradiation) appear to be the best option. In cases where further surgery is not feasible, reirradiation with curative intent remains an alternative, although further research in this area is required. Studies with longer follow-up, focusing particu larly on the different histological subtypes of SNM sharing similar radiosensitivities, are required to better judge its efficacy. Toxicity varies according to the method employed but, in general, appears acceptable. Due to the rarity of these malignancies and the diverse range of histological types with different behaviors, large prospective studies remain difficult to conduct. For this reason, large-scale col laborative multicenter studies with pooling of resources remain the most likely source of future evidence. Technical advances have accelerated the development of highly conformal, image-guided (IG) external beam radio therapy (EBRT). IG-EBRT can be delivered with multi ple treatment modalities, including conventional photons such as static or rotational IMRT and particle therapy (PT). These techniques allow dose escalation and geometric conformity, which are critical for the safe and effective treatment of SNM. Cancers of this anatomic region por tend a high risk of tumor recurrence as well as treatment complications from intense multimodality therapies that include surgery, radiation, and chemotherapy. SNMs are often situated immediately adjacent to sensitive neurovas cular tissues (optic apparatus, brainstem, spinal cord, brain parenchyma, auditory structures, mandible, aerodigestive tract mucosa, and/or salivary glands), all of which provide vital functions for daily living and maintaining QOL. Thus, IMRT has been a major advancement in sparing these nor mal tissues and is the current standard for clinical practice worldwide. 22,458,459 PT is an emerging clinical tool using neutrons, protons, or carbon ions for therapeutic intervention. Because of the physical properties of particle dosimetry, other than neutrons, these modalities can reduce the integral dose, specifically low and moderate radiotherapy doses, to sur rounding normal tissues. Proton beam therapy (PBT) is XIV RADIATION MODALITIES FOR TREATMENT OF SINONASAL MALIGNANCIES

the most widespread of this category, showing an asso ciation of improved oncologic control for treating SNM over IMRT. 458 Fast neutron therapy (NRT) and carbon ion radiotherapy (CIRT) involve heavy particles with a higher relative biological effectiveness (RBE), potentially allowing for biologic therapy intensification for those with residual disease of radioresistant pathologies. 458,460–463 Significant heterogeneity in literature across patient demographics, stage, pathologies, and treatment status (including prior intervention and extent of residual dis ease at the time of radiotherapeutic intervention) makes direct comparisons challenging. Furthermore, even among similar modalities, differences in practice patterns and technical operations exist. This section aims to summa rize the evidence on the role of RT and different modalities on management of SNM. Of note, this section does not cover radiation treatment of chordoma or skull base chon drosarcoma, which is covered in ICSB 2019 Sections IX.A.6 and IX.B.1, respectively. 5 Section XXX.II covers morbidity related to RT. A Intensity-modulated radiotherapy Commercially available since the early 2000s, IMRT has quickly become the primary radiation delivery method in advanced centers. Benefits are multifactorial, with short treatment times and the ability to deliver multi ple noncoplanar beam angles by rotational arcs with high dose rates and sophisticated multileaf collimation. IMRT can thus generate steep dose gradients and high dose conformity, which is essential for treating SNM. When compared to two-dimensional and three dimensional conformal radiotherapy techniques (2DCRT and 3DCRT, respectively), retrospective case series show that IMRT has reduced toxicity and local control (LC) and OS benefits (Table XIV.1). Al-Mamgani et al. reviewed 82 patients with SNM and reported that, though late grade 2 toxicity was seen in over 25% of patients 5 years after treatment, it was significantly lower when using IMRT compared to 3DCRT (17% vs. 52%, p < 0.0001). Not only was visual preservation improved using IMRT (88% vs. 65%; p = 0.01), but it also demonstrated LC advantages (80% vs. 64%; p = 0.2). 462 Furthermore, Duprez et al. reviewed 130 SNM patients treated with IMRT. While they observed late grade 3 ocu lar toxicity in 11 patients, no radiation-induced blindness was observed. Actuarial 5-year LC and OS rates were 59% and 52%, respectively. They concluded that IMRT could deliver high therapeutic doses and minimize ocular com plications and should be the SNM treatment standard. 464 The adoption of IMRT and multimodality therapy was fur ther corroborated in a phase-4 national study in Denmark.