Journal of Medical Imaging and Radiation Oncology 58 (2014) 253–256 bs_bs_banner
R ADIATION O N C O LO GY —O R I G I N AL A RTICLE
Gas in the rectum tends to reduce during radical external beam radiotherapy for localised prostate cancer Naoki Nakamura,1 Shogo Hatanaka,4 Osamu Takahashi,2 Norifumi Mizuno,1 Haruna Endo,1 Seiichi Tamaki,1,3 Naoto Shikama,5 Mami Ogita,1 Jiro Kawamori1 and Kenji Sekiguchi1 1
Department of Radiation Oncology, and 2Division of General Internal Medicine, Department of Medicine, St. Luke’s International Hospital, and Department of Physics, Rikkyo University, Tokyo, and 4Department of Radiation Oncology, Kanagawa Cancer Center, Yokohama, and 5Department of Radiation Oncology, Saitama Medical University International Medical Center, Hidaka, Japan 3
N Nakamura MD; S Hatanaka MPH; O Takahashi MD; N Mizuno BS; H Endo MPH; S Tamaki MPH; N Shikama MD; M Ogita MD; J Kawamori MD; K Sekiguchi MD. Correspondence Mr Naoki Nakamura, Department of Radiation Oncology, St. Luke’s International Hospital, 9-1, Akashicho, Chuoh-ku, Tokyo 104–8560, Japan. Email: [email protected] Conflict of interest: none. Submitted 3 July 2013; accepted 31 October 2013. doi:10.1111/1754-9485.12141
Abstract Purpose: This study aims to clarify the time-course of gas accumulation in the rectum during treatment as guidance for the management of rectal volumes. Materials and Methods: We reviewed 2042 sets (35.2 sets per patient) of anteroposterior and right–left mega voltage (MV) images obtained for daily set-up from 58 patients who underwent radical external beam radiotherapy for localised prostate cancer. The patients were instructed to take magnesium oxide tablets during radiotherapy. They were also encouraged to avoid foods that might cause intestinal gas during radiotherapy. Gas accumulation in the rectum was graded into three classes by the same radiation oncologist. If no gas was seen in the rectum, it was classified as grade 0. A small amount of gas was classified as grade 1, whereas a marked amount of gas that required removal was classified as grade 2. Results: Of the 2042 sets of MV images, grades 1 and 2 gas accumulation were seen in 332 (16%) and 156 (8%), respectively. By the trend test, gas accumulation significantly decreased towards the end of treatment (P = 0.02 for grade 1 or 2 and P = 0.02 for grade 2). On multivariate analysis, we did not identify any significant independent predictors for either baseline gas accumulation or gas reduction. Conclusion: Gas accumulation tended to decrease until the end of treatment. This tendency should be reconfirmed by other institutions. Key words: gas; prostate cancer; radiotherapy; rectal volume.
Introduction It is desirable for rectal and bladder volumes to be kept constant throughout planning and treatment for prostate cancer to reduce inter- or intra-fractional positional uncertainties of the prostate and the risk of increased toxicity to the surrounding normal tissue. However, an interesting trend involving a decline in bladder volumes during the treatment course has been reported.1–3 On the other hand, the aetiology of rectal volumes is poorly understood. Gas in the rectum largely affects the rectal size and shape, which causes prostate movements.4–7 The purpose of this study was to clarify the timecourse of gas accumulation in the rectum during treatment as guidance for the management of rectal volumes. © 2013 The Royal Australian and New Zealand College of Radiologists
Materials and methods Patients This study was approved by an Institutional Review Board. Fifty-eight consecutive patients who underwent definitive radiotherapy for localised prostate cancer between 2010 and 2012 at St. Luke’s international hospital were retrospectively reviewed. Patient characteristics are shown in Table 1.
Treatment All patients received seven-port static intensitymodulated radiotherapy with ultrasound image guidance. Forty patients (69%) received neoadjuvant and 253
N Nakamura et al.
Table 2. The dose constraints and actual prescribed dose for the rectum
Table 1. Patient characteristics Characteristics Age Median (range) Body mass index Median (range) Past history of abdominal surgery Yes No Clinical T stage (UICC 7th edition) 1–2a 2b 2c–4 Gleason score 6 7 8–10 Initial PSA (ng/mL)
R ADIATION O N C O LO GY —O R I G I N AL A RTICLE
Gas in the rectum tends to reduce during radical external beam radiotherapy for localised prostate cancer Naoki Nakamura,1 Shogo Hatanaka,4 Osamu Takahashi,2 Norifumi Mizuno,1 Haruna Endo,1 Seiichi Tamaki,1,3 Naoto Shikama,5 Mami Ogita,1 Jiro Kawamori1 and Kenji Sekiguchi1 1
Department of Radiation Oncology, and 2Division of General Internal Medicine, Department of Medicine, St. Luke’s International Hospital, and Department of Physics, Rikkyo University, Tokyo, and 4Department of Radiation Oncology, Kanagawa Cancer Center, Yokohama, and 5Department of Radiation Oncology, Saitama Medical University International Medical Center, Hidaka, Japan 3
N Nakamura MD; S Hatanaka MPH; O Takahashi MD; N Mizuno BS; H Endo MPH; S Tamaki MPH; N Shikama MD; M Ogita MD; J Kawamori MD; K Sekiguchi MD. Correspondence Mr Naoki Nakamura, Department of Radiation Oncology, St. Luke’s International Hospital, 9-1, Akashicho, Chuoh-ku, Tokyo 104–8560, Japan. Email: [email protected] Conflict of interest: none. Submitted 3 July 2013; accepted 31 October 2013. doi:10.1111/1754-9485.12141
Abstract Purpose: This study aims to clarify the time-course of gas accumulation in the rectum during treatment as guidance for the management of rectal volumes. Materials and Methods: We reviewed 2042 sets (35.2 sets per patient) of anteroposterior and right–left mega voltage (MV) images obtained for daily set-up from 58 patients who underwent radical external beam radiotherapy for localised prostate cancer. The patients were instructed to take magnesium oxide tablets during radiotherapy. They were also encouraged to avoid foods that might cause intestinal gas during radiotherapy. Gas accumulation in the rectum was graded into three classes by the same radiation oncologist. If no gas was seen in the rectum, it was classified as grade 0. A small amount of gas was classified as grade 1, whereas a marked amount of gas that required removal was classified as grade 2. Results: Of the 2042 sets of MV images, grades 1 and 2 gas accumulation were seen in 332 (16%) and 156 (8%), respectively. By the trend test, gas accumulation significantly decreased towards the end of treatment (P = 0.02 for grade 1 or 2 and P = 0.02 for grade 2). On multivariate analysis, we did not identify any significant independent predictors for either baseline gas accumulation or gas reduction. Conclusion: Gas accumulation tended to decrease until the end of treatment. This tendency should be reconfirmed by other institutions. Key words: gas; prostate cancer; radiotherapy; rectal volume.
Introduction It is desirable for rectal and bladder volumes to be kept constant throughout planning and treatment for prostate cancer to reduce inter- or intra-fractional positional uncertainties of the prostate and the risk of increased toxicity to the surrounding normal tissue. However, an interesting trend involving a decline in bladder volumes during the treatment course has been reported.1–3 On the other hand, the aetiology of rectal volumes is poorly understood. Gas in the rectum largely affects the rectal size and shape, which causes prostate movements.4–7 The purpose of this study was to clarify the timecourse of gas accumulation in the rectum during treatment as guidance for the management of rectal volumes. © 2013 The Royal Australian and New Zealand College of Radiologists
Materials and methods Patients This study was approved by an Institutional Review Board. Fifty-eight consecutive patients who underwent definitive radiotherapy for localised prostate cancer between 2010 and 2012 at St. Luke’s international hospital were retrospectively reviewed. Patient characteristics are shown in Table 1.
Treatment All patients received seven-port static intensitymodulated radiotherapy with ultrasound image guidance. Forty patients (69%) received neoadjuvant and 253
N Nakamura et al.
Table 2. The dose constraints and actual prescribed dose for the rectum
Table 1. Patient characteristics Characteristics Age Median (range) Body mass index Median (range) Past history of abdominal surgery Yes No Clinical T stage (UICC 7th edition) 1–2a 2b 2c–4 Gleason score 6 7 8–10 Initial PSA (ng/mL)
