Seymour Zachary A, Chang Albert J, Zhang Li, Kirby Neil, Descovich Martina, Roach Mack, Hsu I-Chow, Gottschalk Alexander R
Department of Radiation Oncology, University of California at San Francisco, San Francisco, California.
Department of Radiation Oncology, University of California at San Francisco, San Francisco, California.
Pract Radiat Oncol. 2015 Sep-Oct;5(5):e465-e472. doi: 10.1016/j.prro.2015.02.001. Epub 2015 Mar 18.
The purpose of this study was to evaluate the dose-volume relationships of genitourinary toxicity after stereotactic body radiation therapy (SBRT) monotherapy for prostate cancer.
Fifty-six patients diagnosed with low- to intermediate-risk prostate cancer treated with SBRT alone were reviewed retrospectively. All patients received a total dose of 38 Gy in 4 fractions with a planning target volume expansion of 2 mm. Overall, acute, and late genitourinary toxicity were documented according to the Common Terminology Criteria for Adverse Events (version 4) and International Prostate Symptom Scores (IPSS).
The median age at treatment was 68 years, and the median prostate volume was 45.5 mL, with a median baseline IPSS of 9.95. The median prescription isodose line was 68%. The median clinical follow-up was 35.49 months. Acute grade 1, 2, and 3 genitourinary toxicities occurred in 41.1%, 35.7%, and 0% of patients. All acute genitourinary toxicities resolved except 1 patient with grade 2 toxicity that progressed to grade 3 late toxicity. No dose-volume relationships were associated with acute genitourinary grade 2+ toxicity. Late grade 1, 2, and 3 genitourinary toxicity occurred in 19.6%, 19.6%, and 3.6% of cases, respectively. Of the cases with late toxicities, 16.7% were persistent. Late grade 2+ genitourinary toxicity was associated with prostate volume ≥50 mL, lower homogeneity index, and urethral maximum point dose ≥47 Gy. The overall risk of any grade 2+ genitourinary toxicity was associated with baseline IPSS >7, prostate volume ≥50 mL, urethral volume receiving 44 Gy, and bladder volume receiving 19 Gy.
SBRT for prostate cancer appears well tolerated, with mostly transient low-grade toxicity. Urethral sparing should be used with a maximum point dose <47 Gy, volume receiving 120 Gy <50% of the prostate, and bladder volume receiving 19 Gy <15 mL in 4 fraction treatments. Patients with prostate volumes ≥50 mL should be counseled regarding the increased risk of moderate-grade genitourinary toxicity.
本研究旨在评估立体定向体部放射治疗（SBRT）单药治疗前列腺癌后泌尿生殖系统毒性的剂量-体积关系。
回顾性分析56例仅接受SBRT治疗的低至中危前列腺癌患者。所有患者接受4次分割、总剂量38 Gy的治疗，计划靶体积外放2 mm。根据不良事件通用术语标准（第4版）和国际前列腺症状评分（IPSS）记录总体急性和晚期泌尿生殖系统毒性。
治疗时的中位年龄为68岁，中位前列腺体积为45.5 mL，基线IPSS中位数为9.95。中位处方等剂量线为68%。中位临床随访时间为35.49个月。41.1%、35.7%和0%的患者发生急性1级、2级和3级泌尿生殖系统毒性。除1例2级毒性进展为3级晚期毒性的患者外，所有急性泌尿生殖系统毒性均得到缓解。急性泌尿生殖系统2级及以上毒性与剂量-体积关系无关。晚期1级、2级和3级泌尿生殖系统毒性分别发生在19.6%、19.6%和3.6%的病例中。在发生晚期毒性的病例中，16.7%为持续性毒性。晚期2级及以上泌尿生殖系统毒性与前列腺体积≥50 mL、较低的均匀性指数以及尿道最大点剂量≥47 Gy相关。任何2级及以上泌尿生殖系统毒性的总体风险与基线IPSS>7、前列腺体积≥50 mL、接受44 Gy照射的尿道体积以及接受19 Gy照射的膀胱体积相关。
前列腺癌的SBRT耐受性良好，主要为短暂的低级别毒性。在4次分割治疗中，应采用尿道保护措施，最大点剂量<47 Gy，接受120 Gy照射的体积<前列腺体积的50%，接受19 Gy照射的膀胱体积<15 mL。对于前列腺体积≥50 mL的患者，应告知其发生中度泌尿生殖系统毒性的风险增加。
