Treatment outcomes and dose-volume histogram analysis of simultaneous integrated boost method for malignant gliomas using intensity-modulated radiotherapy

Abstract

Our IMRT regimen did not prevent tumor progression. However, the ability of IMRT to deliver highly conformative doses to two contiguous targets, GTV and the surrounding edema, justifies its application to malignant gliomas.

Simultaneous Integrated Boost Intensity-Modulated Radiotherapy in Patients With High-Grade Gliomas

“…Therefore, the biologically effective dose (BED) delivered to the GTV was estimated by assuming an a/b ratio of 10 Gy, an effective doubling time of 5 days, and a kickoff time for accelerated repopulation of 14 days. The BED ranged from 72.5 Gy (14,17) to 126.9 Gy (16), and ours was the lowest at 66.1 Gy. Chemotherapy was commonly administered for patients with GBM, consisting of concurrent and adjuvant TMZ in most cases.…”

“…Chemotherapy was commonly administered for patients with GBM, consisting of concurrent and adjuvant TMZ in most cases. Local failure was a major pattern of failure (14,16,17), occurring in greater than 60% of patients, but in one study (15) LF occurred only in 24% of patients. In the last study, the highest BED of 126.9 Gy was given to the GTV, and the authors claimed that the higher BED was associated with the greater PFS and OS rates.…”

“…Despite a very large dose (6-8.5 Gy) per fraction used in that study, only 1 (4%) patient had acute grade 1 toxicity, and 3 (12%) patients had late brain necrosis requiring reoperation. Nakamutsu et al (16) reported outcomes of 13 patients with HGG treated with SIB-IMRT. A dose of 70 Gy and 56 Gy in 28 fractions were delivered to the GTV plus a 5-mm margin and to surrounding edema, respectively.…”

“…Two studies included GBM patients only (14,17), and the remaining two studies (15,16) included both grade III and IV tumors. Target definition varied among studies, particularly for the PTV receiving the lower tier of doses from the GTV plus a 15-mm margin (14,17) to the peritumoral edema (15).…”

Dose Escalation in Prostate Radiotherapy up to 82 Gy Using Simultaneous Integrated Boost

“…IMRT offers not only critical structure sparing, but also irradiation of different targets at different dose levels within a single treatment session. This treatment strategy, termed simultaneous integrated boost (SIB), has been introduced for several anatomic sites [6,8,15,22,23]. The use of SIB may reduce the dose to the rectal wall and diminish normal-tissue complications.…”