The Role Of Image Guided And Intensity Modulated Stereotactic Radiotherapy For Patients With Metastatic And Locally Advanced Cancers

Background Intensity-modulated stereotactic radiotherapy achieves improvements in the ability to produce conformal stereotactic dose distributions by modulation of the intensity of individually delivered beamlets of radiation. Image-guided intensity-modulated stereotactic radiotherapy has emerged as a new treatment option in the multidisciplinary management of metastatic and locally advanced cancers. Methods From July 2009 to February 2010, 34 patients with metastatic and locally advanced cancers were treated with an image-guided intensity-modulated stereotactic radiation system, Axesse (Elekta, Crawley, England). The patient position was verified using CBCT of the Elekta Axesse. Patient setup errors were calculated using automatic image registration of the planning CT scan and verification CBCT scan using the Elekta XVI software. Errors were corrected on-line before each treatment. Results The group mean errors were ? 1 mm and ? 1°. Radiologic complete response was achieved in 8 patients (23.5%). Radiologic partial response was achieved in 25 patients (73.6%). Development of new intracranial lesion was noted in one patient with brain metastasis from lung cancer (2.9%). Radiologic local control was achieved in 33 patients (97.1%). Clinical symptom improvement, including relief of pain and other symptoms, was achieved in all patients. Conclusion Image-guided intensity-modulated stereotactic radiotherapy used in the treatment of patients with metastatic and locally advanced cancer appears to be safe and effective both in terms radiographic tumor control and pain relief. Clinical trials providing standards on treatment parameters, physics quality assurance benchmarks, and tools to measure outcomes are warranted. Introduction Recently, significant progress has been made in advancing the state-of-the-art in stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) treatment delivery through the adoption of intensity modulated radiosurgery/therapy (IMRS/IMRT) approaches [1-3]. IMRS/IMRT achieves improvements in the ability to produce conformal stereotactic dose distributions by modulation of the intensity of individually delivered beamlets of radiation [4-6]. The ability to deliver modulated beamlets of radiation is implemented by use of multileaf collimators (MLC) to segment the large linac-produced radiation beam into small beamlets, or pencil beams. Intensity, or dose, is modulated by varying the amount of time that one pencil beam is exposed, relative to the others [7-9]. Linear accelerators capable of kilovoltage cone-beam computed tomography (CBCT) imaging and intensity modulated dose delivery are used in radiotherapy to improve treatment guidance while achieving highly conformal dose distributions [9-13]. Image-guided intensity-modulated stereotactic radiotherapy has emerged as a new treatment option in the multidisciplinary management of metastatic and locally advanced cancers [9, 14-16]. Sahgal et al. published a comprehensive review concerning the emerging technique of stereotactic body radiosurgery for spinal metastases [17]. Using state-of-the-art image-guided intensity-modulated stereotactic approach, radiotherapy can be focused more precisely. It can be used to treat metastatic and locally advanced cancers in which the conventional approach would not allow delivery of adequate radiation doses to the planning target volume (PTV) in combination with sparing of normal tissue [15, 18, 19]. The present study reports the preliminary results of intensity-modulated stereotactic radiotherapy and daily cone-beam computed tomography (CBCT)-based image guidance with on-line correction of setup errors for patients with metastatic and locally advanced cancers. WebmedCentral > Original Articles Page 2 of 11 WMC001153 Downloaded from http://www.webmedcentral.com on 30-Dec-2011, 07:19:49 AM