Intensity-Modulated Radiotherapy of Pelvic Lymph Nodes in Locally Advanced Prostate Cancer: Planning Procedures and Early Experiences

Abstract

Purpose: We present planning and early clinical outcomes of a study of intensity-modulated radiotherapy (IMRT) for locally advanced prostate cancer. Methods and Materials: A total of 43 patients initially treated with an IMRT plan delivering 50 Gy to the prostate, seminal vesicles, and pelvic lymph nodes, followed by a conformal radiotherapy (CRT) plan delivering 20 Gy to the prostate and seminal vesicles, were studied. Dose-volume histogram (DVH) data for the added plans were compared with dose-volume histogram data for the sum of two CRT plans for 15 cases. Gastrointestinal (GI) and genitourinary (GU) toxicity, based on the Radiation Therapy Oncology Group scoring system, was recorded weekly throughout treatment as well as 3 to 18 months after treatment and are presented. Results: Treatment with IMRT both reduced normal tissue doses and increased the minimum target doses. Intestine volumes receiving more than 40 and 50 Gy were significantly reduced (e.g., at 50 Gy, from 81 to 19 cm 3 ; p = 0.026), as were bladder volumes above 40, 50, and 60 Gy, rectum volumes above 30, 50, and 60 Gy, and hip joint muscle volumes above 20, 30, and 40 Gy. During treatment, Grade 2 GI toxicity was reported by 12 of 43 patients (28%), and Grade 2 to 4 GU toxicity was also observed among 12 patients (28%). With 6 to 18 months of follow-up, 2 patients (5%) experienced Grade 2 GI effects and 7 patients (16%) experienced Grade 2 GU effects. Conclusions: Use of IMRT for pelvic irradiation in prostate cancer reduces normal tissue doses, improves target coverage, and has a promising toxicity profile. Ó

Influence of Organ Motion on Conformal vs. Intensity-Modulated Pelvic Radiotherapy for Prostate Cancer

“…Nevertheless, Ashman et al (4) observed a similar redistribution with IMRT and yet their patients experienced an improved GI toxicity profile after IMRT compared with after CRT. Also, the initial clinical results from HUH have been promising (13,26).…”

“…The patient data (16), as well as the procedure for the definition of targets and treatment planning and delivery (including patient setup), has been previously described in detail (13). A brief description of the materials and planning procedures is outlined.…”

“…Several planning studies have demonstrated the superiority of IMRT compared with conformal RT (CRT) to shape the dose distribution to the planning target volume (PTV), thereby reducing the dose to the main organs-at-risk (OARs) (i.e., the bowel, rectum, and bladder) (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Also, a few clinical studies have indicated a better outcome with IMRT (4,6,13,14).…”

Planning Margins to CTV for Image-Guided Whole Pelvis Prostate Cancer Intensity-Modulated Radiotherapy

“…Here in our study we investigate setup uncertainty in case of conventional fractionated treatment. As shown in the literatures [7][8][9][10], margins for PTV in image-guided whole pelvis prostate IMRT vary from 2 -15 mm depending on the setup technique. It should be noted that we focus on image-guidance for setup uncertainty correction in our study, and therefore real time tracking for intrafraction motion correction is not included.…”

“…Intensity-modulated radiotherapy (IMRT) of whole pelvis for prostate cancer patients [7][8][9][10][11][12][13] treats the gross disease in the prostate gland as well as suspected involvement of the distal seminal vesicles (SV) and pelvic lymphatic nodes (PLNs) [7][8][9][10]13], while minimizing doses to rectum, bladder, bowel and surrounding normal tissues. The employment of pre-treatment in-room KV imaging systems, such as cone-beam computed tomography (CBCT), has gained their increasing popularity over the years in image-guided prostate IMRT.…”