Intensity modulated radiotherapy for sinonasal malignancies with a focus on optic pathway preservation

Abstract

PurposeTo assess if intensity-modulated radiotherapy (IMRT) can possibly lead to improved local control and lower incidence of vision impairment/blindness in comparison to non-IMRT techniques when treating sinonasal malignancies; what is the most optimal dose constraints for the optic pathway; and the impact of different IMRT strategies on optic pathway sparing in this setting.Methods and materialsA literature search in the PubMed databases was conducted in July, 2012.ResultsClinical studies on IMRT and 2D/3D (2 dimensional/3 dimensional) RT for sinonasal malignancies suggest improved local control and lower incidence of severe vision impairment with IMRT in comparison to non-IMRT techniques. As observed in the non-IMRT studies, blindness due to disease progression may occur despite a lack of severe toxicity possibly due to the difficulty of controlling locally very advanced disease with a dose ≤ 70 Gy. Concurrent chemotherapy’s influence on the the risk of severe optic toxicity after radiotherapy is unclear. A maximum dose of ≤ 54 Gy with conventional fractionation to the optic pathway may decrease the risk of blindness. Increased magnitude of intensity modulation through increasing the number of segments, beams, and using a combination of coplanar and non-coplanar arrangements may help increase dose conformality and optic pathway sparing when IMRT is used.ConclusionIMRT optimized with appropriate strategies may be the treatment of choice for the most optimal local control and optic pathway sparing when treating sinonasal malignancy.

NCCN Guidelines Insights: Head and Neck Cancers, Version 1.2018

“…63,64 It is useful in reducing long-term toxicity in H&N cancers and particularly NPC by reducing the dose to ≥1 major salivary glands, temporal lobes, mandible, auditory structures (including the cochlea), and optic structures. [65][66][67][68][69] IMRT may help to preserve the optic pathway in patients with sinonasal malignancies. 65 A prospective Korean study showed that 3-dimensional and IMRT techniques were superior to 2-dimensional radiation for both PFS and OS, and IMRT was associated with improved survival in multivariate analysis, particularly in T3-T4 tumors.…”

“…[65][66][67][68][69] IMRT may help to preserve the optic pathway in patients with sinonasal malignancies. 65 A prospective Korean study showed that 3-dimensional and IMRT techniques were superior to 2-dimensional radiation for both PFS and OS, and IMRT was associated with improved survival in multivariate analysis, particularly in T3-T4 tumors. 70 Proton therapy has also been used to treat sinonasal malignancies.…”

AHNS Series: Do you know your guidelines?Principles of radiation therapy for head and neck cancer: A review of the National Comprehensive Cancer Network guidelines

“…11 IMRT has been shown to reduce longterm toxicity in oropharyngeal, paranasal, and nasopharyngeal cancers without any compromise in overall survival. [12][13][14][15][16][17] NCCN guidelines currently state a preference for the use of either IMRT or 3D conformal RT for treatment of all head and neck subsites, with IMRT preferred for paranasal and nasopharyngeal cancers. Methods of delivering IMRT include the simultaneous integrated boost (SIB) and sequential (SEQ) technique.…”

“…IMRT involves the modulation of radiation beams to reduce doses to normal structures while still delivering effective doses to target sites, utilizing computer‐based inverse planning . IMRT has been shown to reduce long‐term toxicity in oropharyngeal, paranasal, and nasopharyngeal cancers without any compromise in overall survival . NCCN guidelines currently state a preference for the use of either IMRT or 3D conformal RT for treatment of all head and neck subsites, with IMRT preferred for paranasal and nasopharyngeal cancers.…”

Radiotherapy in patients with connective tissue diseases

“…In this disease, intensity-modulated radiotherapy decreased long-term toxicity with no negative eff ect on overall survival when compared with 3D-conformal radiotherapy. [54][55][56][57][58][59][60][61][62][63][64][65][66] Stereotactic ablative radiotherapy is a novel radiotherapy method that delivers a very high dose of radiation (in a single or a few fractions) with high precision to the tumour, thus maximising the sparing of surrounding normal tissue. Several retrospective and prospective stereotactic ablative radiotherapy studies have shown promising results in terms of local tumour control and survival in some settings, including in early non-small-cell lung cancer.…”