Optimization of Radiation Therapy for Locally Advanced Adenoid Cystic Carcinomas with Infiltration of the Skull Base Using Photon Intensity-Modulated Radiation Therapy (IMRT) and a Carbon Ion Boost

Abstract

The combination of photon IMRT with carbon ions improves the target coverage for the boost volume and offers better sparing of OAR close to the PTV2 (gross tumor volume) in comparison with photon IMRT alone. A clinical study has been initiated to evaluate whether these potential advantages translate into clinical benefit.

Verification of IMRT: Techniques and Problems

“…The evaluation of the verification of five patient treatment plans, three of which had been calculated with a sequential boost and two with a SIB-technique [27,31], showed absolute dose deviations, which seemed to depend on the number of segments. In five IMRT plans with about 70 segments we found deviations of -6% (± 1,0%), whereas two boost cases with 30 segments somehow resulted in lower deviations of -5% (±1%).…”

Osteoradionecrosis of the Mandibula in Patients Treated with Different Fractionations

“…Newer techniques of irradiation with an important reduction of the mandibular dose will probably reduce the risk of ON to a very low value [27].…”

Sinonasal Tract and Nasopharyngeal Adenoid Cystic Carcinoma: A Clinicopathologic and Immunophenotypic Study of 86 Cases

“…Due to the prolonged clinical course, radiation when combined with surgery does not seem to significantly alter overall patient outcome (p = 0.545), but may result in longer disease free survival. One of the factors may be that the doses required for local control in ACC ([70 Gy) often cannot be achieved in the confines of the SNT without violating tolerance doses for the adjacent organs or structures (ocular or visual toxic effects: keratitis, photophobia, conjunctivitis, blindness; neurologic: seizures, short-term memory loss, brain changes) [6,55,86,92]. In this series, patients managed with surgery alone, had an average follow-up of 12.2 years, with 58.7 % dead of disease, while patients managed with combination therapy had an average follow-up of 8.8 years, with 50 % dead of disease.…”

“…Since the disease is progressive and indolent, radiation is probably at best palliative, delaying rather than preventing recurrences and providing symptomatic relief while not significantly altering long term outcome [7,106]. Modifications of radiation regimens (carbon ion boost and photo intensity-modulated radiation therapy) may yield a better response, but requires more careful evaluation [24,86,92]. While STACC is radiosensitive, radiation alone is not considered curative [6].…”

“…Specifically, the series often present all salivary gland tumor types together [39,40,57,67,89,91,97,99,106,[120][121][122][123][124][125][126][127], encompass all head and head anatomic sites, describe adenoid cystic carcinoma only but in all sites [5, 6, 12, 17, 22, 31, 32, 35, 39, 47, 50, 52, 57, 59, 66, 73, 75, 76, 87, 91-93, 98, 100, 101, 106, 112, 113, 117, 128-130], or only one subsite but all tumors combined. Many small series focus on the radiographic findings alone [36, 62, 88, 96, 99, 108-110, 112, 117, 131-134], or specifically address a particular therapy (radiation) [8,20,24,25,33,54,63,66,69,86,92,95,111] for all tumor types of a particular anatomic site. It is the intention of this study to provide a comprehensive analysis of STACC incorporating the use of clinical features, histologic findings, immunohistochemical results, therapies employed, and patient follow-up applied to a group of 86 patients with this tumor, generating statistically significant findings.…”