Whole brain radiotherapy plus simultaneous in-field boost with image guided intensity-modulated radiotherapy for brain metastases of non-small cell lung cancer

Abstract

Background: Whole brain radiotherapy (WBRT) plus sequential focal radiation boost is a commonly used therapeutic strategy for patients with brain metastases. However, recent reports on WBRT plus simultaneous in-field boost (SIB) also showed promising outcomes. The objective of present study is to retrospectively evaluate the efficacy and toxicities of WBRT plus SIB with image guided intensity-modulated radiotherapy (IG-IMRT) for inoperable brain metastases of NSCLC.

Methods: Twenty-nine NSCLC patients with 87 inoperable brain metastases were included in this retrospective study. All patients received WBRT at a dose of 40 Gy/20 f, and SIB boost with IG-IMRT at a dose of 20 Gy/5 f concurrent with WBRT in the fourth week. Prior to each fraction of IG-IMRT boost, on-line positioning verification and correction were used to ensure that the set-up errors were within 2 mm by cone beam computed tomography in all patients.

Results: The one-year intracranial control rate, local brain failure rate, and distant brain failure rate were 62.9%, 13.8%, and 19.2%, respectively. The two-year intracranial control rate, local brain failure rate, and distant brain failure rate were 42.5%, 30.9%, and 36.4%, respectively. Both median intracranial progression-free survival and median survival were 10 months. Six-month, one-year, and two-year survival rates were 65.5%, 41.4%, and 13.8%, corresponding to 62.1%, 41.4%, and 10.3% of intracranial progression-free survival rates. Patients with Score Index for Radiosurgery in Brain Metastases (SIR) >5, number of intracranial lesions <3, and history of EGFR-TKI treatment had better survival. Three lesions (3.45%) demonstrated radiation necrosis after radiotherapy. Grades 2 and 3 cognitive impairment with grade 2 radiation leukoencephalopathy were observed in 4 (13.8%) and 4 (13.8%) patients. No dosimetric parameters were found to be associated with these late toxicities. Patients received EGFR-TKI treatment had higher incidence of grades 2-3 cognitive impairment with grade 2 leukoencephalopathy.

Conclusions: WBRT plus SIB with IG-IMRT is a tolerable and effective treatment for NSCLC patients with inoperable brain metastases. However, the results of present study need to be examined by the prospective investigations.

Figure 1

Treatment schedule. All patients received WBRT at a dose of 40 Gy/20 f/4 weeks, and SIB with IG-IMRT at a dose of 20 Gy/5 f concurrent with WBRT in the fourth week. Steroids (dexamethasone) were administered to all patients in the fourth week of radiotherapy. Abbreviations: WBRT = whole brain radiotherapy; IG-IMRT = image guided intensity-modulated radiotherapy; treatment delivery.

Figure 2

Overall survival of the whole patients. The Kaplan-Meier overall survival curve of whole group showed the six-month, one-year and two-year survival rates were 65.5%, 41.4% and 13.8%, respectively.

Figure 3

IC-PFS of the whole patients. The Kaplan-Meier IC-PFS curve of whole group showed the six-month, one-year and two-year IC-PFS rates were 62.1%, 41.4% and 10.3%, respectively. Abbreviations: IC-PFS = intracranial progression-free survival.