Simultaneous integrated boost by RapidArc therapy plus temozolomide for treatment of patients with glioblastoma multiform: A single institution experience

Abstract

The aim of this study is to report the treatment outcomes, toxicities, and dosimetric feasibility of simultaneous integrated boost by RapidArc (RA-SIB) compared with 3dimentional-conformal radiation therapy (3D-CRT) for patients with glioblastoma. Methods: Eleven patients with unifocal glioblastoma (grade IV astrocytoma, WHO classification) were treated during the period from April 2011 until February 2013 with postoperative irradiation and concomitant temozolomide 75 mg/m 2 followed by 6-12 months of adjuvant temozolomide 200 mg/m 2 for 5 days/4weeks. One patient received temozolomide for 12 months, 5patients for 6 months, and 5patients did not receive adjuvant temozolomide. RA-SIB technique was used and patients received 46 Gy per fraction of 2 Gy in 23 sessions on the planning target volume (PTV1) (contrast enhancement + per-focal edema as seen in T2 MR + 2.3 cm) with concomitant daily superimposed boost (SIB) on PTV2 corresponding to the contrast enhancement + 2.3 cm. The treatment outcomes and toxicity were assessed. Dose Volume Histogram DVH analysis was performed between SIB-RA and 3D-CRT plans of each patient. For the PTV, the comparison parameters included, the mean dose, the standard deviation, maximum dose, conformity index (CI), and homogeneity index (HI). Results: The median progression free survival (PFS) and overall survival (OS) were 13 months (95% CI, 8.2-17.8), and 16 months (95% CI, 2.1-29.9) respectively. Four of six patients (67%) showed local progression (recurrence) after initial response, all recurrences occurred at the site of PTV2. Seven patients experienced acute grade 1-2 toxicities during the treatment. Late post radiation brain edema was reported in 3 patients. Conclusion: The SIB-RA did not prove the superiority in survival outcomes compared with the historical data using 3D-CRT. From the dosimetric standpoint, SIB-RA is a superior technique with respect to 3D-CRT when there are overlaps between organs at risk (OARs) and PTV.

Study of dosimetric indices and dose constraints to critical organs for head and neck tumours treated with inverse planned simultaneous integrated boost intensity-modulated radiotherapy

“…A literature survey highlights the importance of shrinking field IMRT technique over three-dimensional conformal radiotherapy and RapidArc techniques 15 16 Based on published data it was observed that SIB not only provides a high conformal dose distribution and better coverage to the target volume but also protect susceptible organs 45 …”

“…43 A literature survey highlights the importance of shrinking field IMRT technique over threedimensional conformal radiotherapy and RapidArc techniques. 15,16 Based on published data it was observed that SIB not only provides a high conformal dose distribution and better coverage to the target volume but also protect susceptible organs. [45][46][47] Doses to low risk PTV and boosted high risk PTV are delivered in a single plan with different doses per fraction in contrast to sequential boost (SEQ) technique.…”

“…TDs given in Table 1 are based on a comprehensive review of the literature. 1,[11][12][13][14][15][16][17][18] Dose constraints and priorities of organs for treatment planning are in accordance with Danish Head and Neck Cancer Group (DAHANCA) (13)(14) as represented in Table 1.…”