マーカー金球による位置補正を併用した前立腺3次元原体外照射療法(3D-CRT)の照射方法と短期安全性

Abstract

臨床病期Cまでの限局性前立腺癌と診断され放射線治療を選択された19例を対象に, マーカー金球による位置補正を併用した前立腺三次元原体外照射療法が, 安全性や照射精度の向上に貢献しているかについて検討した.その結果, マーカーの移動を測定することで, 前立腺が移動していること, 移動距離には個人差があること, 骨盤骨の切除術の既往などがあれば更に大きく移動することがわかった.3ヵ月迄の有害事象はNCI-CTC grade 1の頻尿・排尿痛が8例, grade 2の頻尿が1例, grade 1の直腸炎が5例, grade 2の直腸炎が2例に見られたのみで, 高度な有害事象が少なかった

Three dimensional conformal radiotherapy (3D-CRT) for localized prostate cancer under field adjustment with gold marker implantation was performed according to the treatment strategy based on the clinical risk factors to the patients who chose external beam radiotherapy. The treatment strategy contains indications for laparoscopic staging lymphadenectomy and neoadjuvant combined androgen blockade (CAB). This protocol was applied to 19 patients at Kagawa University Hospital from July 2001 to December 2003. The patients were divided into high-risk group (n=14): T3-4N0M0 or PSA > or = 20 ng/ml or Gleason sum > or = 8 or suspicious node, and low-risk group (n=5): T1c-2bN0M0 and PSA < 20 ng/ml and Gleason sum < or = 7 and no suspicious nodes. Basically, high-risk patients underwent laparoscopic staging lymphadenectomy prior to radiotherapy. One of the 14 patients had a positive node and underwent endocrine therapy. The high-risk group received neoadjuvant CAB for 3 to 4 months, followed by gold marker implantation. One patient chose endocrine therapy at this point. Low-risk patients underwent marker implantation without endocrine therapy. Every patient successfully completed planned irradiation. The changes of prostate volume and serum PSA after neoadjuvant CAB were significant [28.7 ml to 15.7 ml (p=0.004) and 53.9 ng/ml to 1.4 ng/ml (p=0.023), respectively]. Only one patient in the high-risk group had biochemical failure. No grade 3 or 4 adverse events occurred in NCI-CTC grading. The analysis of gravity center migration of the implanted gold markers in the first 8 patients showed that the planned safety margin might not be wide enough to avoid neighboring organ irradiation. These results suggested that 3D-CRT under field adjustment with implanted gold markers contributes to both higher efficacy and lower morbidity.