Ono Takashi, Sato Hiraku, Miyasaka Yuya, Hagiwara Yasuhito, Yano Natsuko, Akamatsu Hiroko, Harada Mayumi, Ichikawa Mayumi
Department of Radiation Oncology, Faculty of Medicine, Yamagata University, Yamagata 990-9585, Japan.
Department of Heavy Particle Medical Science, Yamagata University Graduate School of Medical Science, Yamagata 990-9585, Japan.
World J Radiol. 2024 Jul 28;16(7):256-264. doi: 10.4329/wjr.v16.i7.256.
Carbon ion radiotherapy (CIRT) is currently used to treat prostate cancer. Rectal bleeding is a major cause of toxicity even with CIRT. However, to date, a correlation between the dose and volume parameters of the 12 fractions of CIRT for prostate cancer and rectal bleeding has not been shown. Similarly, the clinical risk factors for rectal bleeding were absent after 12 fractions of CIRT.
To identify the risk factors for rectal bleeding in 12 fractions of CIRT for prostate cancer.
Among 259 patients who received 51.6 Gy [relative biological effectiveness (RBE)], in 12 fractions of CIRT, 15 had grade 1 (5.8%) and nine had grade 2 rectal bleeding (3.5%). The dose-volume parameters included the volume (cc) of the rectum irradiated with at least x Gy (RBE) (Vx) and the minimum dose in the most irradiated x cc normal rectal volume (Dx).
The mean values of D6cc, D2cc, V10 Gy (RBE), V20 Gy (RBE), V30 Gy (RBE), and V40 Gy (RBE) were significantly higher in the patients with rectal bleeding than in those without. The cutoff values were D6cc = 34.34 Gy (RBE), D2cc = 46.46 Gy (RBE), V10 Gy (RBE) = 9.85 cc, V20 Gy (RBE) = 7.00 cc, V30 Gy (RBE) = 6.91 cc, and V40 Gy (RBE) = 4.26 cc. The D2cc, V10 Gy (RBE), and V20 Gy (RBE) cutoff values were significant predictors of grade 2 rectal bleeding.
The above dose-volume parameters may serve as guidelines for preventing rectal bleeding after 12 fractions of CIRT for prostate cancer.
碳离子放疗（CIRT）目前用于治疗前列腺癌。即使采用CIRT，直肠出血仍是毒性的主要原因。然而，迄今为止，尚未显示前列腺癌CIRT 12次分割的剂量和体积参数与直肠出血之间存在相关性。同样，CIRT 12次分割后直肠出血的临床危险因素也尚不明确。
确定前列腺癌CIRT 12次分割中直肠出血的危险因素。
在259例接受51.6 Gy[相对生物效应（RBE）]、CIRT 12次分割的患者中，15例出现1级直肠出血（5.8%），9例出现2级直肠出血（3.5%）。剂量体积参数包括至少接受x Gy（RBE）照射的直肠体积（cc）（Vx）以及照射剂量最高的x cc正常直肠体积中的最小剂量（Dx）。
出现直肠出血的患者中，D6cc、D2cc、V10 Gy（RBE）、V20 Gy（RBE）、V30 Gy（RBE）和V40 Gy（RBE）的平均值显著高于未出现直肠出血的患者。临界值分别为D6cc = 34.34 Gy（RBE）、D2cc = 46.46 Gy（RBE）、V10 Gy（RBE） = 9.85 cc、V20 Gy（RBE） = 7.00 cc、V30 Gy（RBE） = 6.91 cc和V40 Gy（RBE） = 4.26 cc。D2cc、V10 Gy（RBE）和V20 Gy（RBE）的临界值是2级直肠出血的显著预测指标。
上述剂量体积参数可作为前列腺癌CIRT 12次分割后预防直肠出血的指导原则。
