The Potential of Helical Tomotherapy in the Treatment of Head and Neck Cancer

Abstract

A decade after its first introduction into the clinic, little is known about the clinical impact of helical tomotherapy (HT) on head and neck cancer (HNC) treatment. Therefore, we analyzed the basics of this technique and reviewed the literature regarding HT's potential benefit in HNC. The past two decades have been characterized by a huge technological evolution in photon beam radiotherapy (RT). In HNC, static beam intensitymodulated radiotherapy (IMRT) has shown superiority over three-dimensional conformal RT in terms of xerostomia and is considered the standard of care. However, the next-generation IMRT, the rotational IMRT, has been introduced into the clinic without any evidence of superiority over static beam IMRT other than being substantially faster. Of these rotational techniques, HT is the first system especially developed for IMRT in combination with image-guided RT. HT is particularly promising for the treatment of HNC because its sharp dose gradients maximally spare the many radiosensitive organs at risk nearby. In addition, HT's integrated computed tomography scan assures a very precise dose administration and allows for some adaptive RT. Because HT is specifically developed for IMRT in combination with (integrated) imageguidance, it allows for precise dose distribution ("dose painting"), patient setup, and dose delivery. As such, it is an excellent tool for difficult HNC irradiation. The literature on the clinical results of HT in HNC all show excellent short-term (Յ2 years) results with acceptable toxicity profiles. However, properly designed trials are still warranted to further substantiate these results. The Oncologist 2013;18:697-706 Implications for Practice: This article highlights the advantages of helical tomotherapy in the treatment of head and neck cancer as it combines three recent evolutions and challenges in radiotherapy in an integrated system. (1) A rotational IMRT technique that is very efficient in generating homogeneous dose distributions to the target volume while sparing the organs at risk more precisely than conventional IMRT approaches. (2) Three-dimensional image guidance permits a more precise administration of the radiation than the classical two-dimensional imaging. This allows for reduction of the safety margins, which in turn, reduces toxicity. (3) Adaptive radiotherapy is still very labor intensive and no software is able to provide daily online adaptation. Tomotherapy offers a platform that allows for pioneering attempts at adaptive radiotherapy with the possibility of recalculating the administered treatment based on the daily CT scan. Properly designed trials are still warranted to further substantiate the results of this promising treatment modality. INTRODUCTIONDespite major progress in locoregional control, the treatment outcomes of locoregionally advanced head and neck cancer (HNC) remain poor, with a 5-year survival rate of approximately 35% due to the development of distant metastases, locoregional failures, second primaries, and/or comorbidities [1][...

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