背景:碳离子放射治疗(CIRT)目前用于治疗前列腺癌。即使使用CIRT,直肠出血也是毒性的主要原因。然而,到目前为止,对于前列腺癌和直肠出血,CIRT的12个分数的剂量和体积参数之间没有相关性.同样,12次CIRT后,直肠出血的临床危险因素不存在。
目的:确定前列腺癌12个部分CIRT中直肠出血的危险因素。
方法:在259名接受51.6Gy[相对生物学有效性(RBE)]的患者中,在CIRT的12个部分中,15名患者为1级(5.8%),9名患者为2级直肠出血(3.5%)。剂量-体积参数包括用至少xGy(RBE)(Vx)辐照的直肠体积(cc)和辐照最多的xcc正常直肠体积(Dx)中的最小剂量。
结果:D6cc的平均值,D2cc,V10Gy(RBE),V20Gy(RBE),V30Gy(RBE),直肠出血患者的V40Gy(RBE)明显高于无直肠出血患者。截止值为D6cc=34.34Gy(RBE),D2cc=46.46Gy(RBE),V10Gy(RBE)=9.85cc,V20Gy(RBE)=7.00cc,V30Gy(RBE)=6.91cc,V40Gy(RBE)=4.26cc。D2cc,V10Gy(RBE),和V20Gy(RBE)临界值是2级直肠出血的显著预测因子.
结论:上述剂量-体积参数可作为预防前列腺癌12次CIRT后直肠出血的指南。
BACKGROUND: 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.
OBJECTIVE: To identify the risk factors for rectal bleeding in 12 fractions of CIRT for prostate cancer.
METHODS: 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).
RESULTS: 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.
CONCLUSIONS: The above dose-volume parameters may serve as guidelines for preventing rectal bleeding after 12 fractions of CIRT for prostate cancer.