Ciernik I Frank, Singh Shubeen, Singh Akash K, Goldschmidt Philipp, Budach Wilfried, Vordermark Dirk, Krayenbuehl Jérôme
Medical School, University of Zürich, Zurich, Switzerland.
Department of Radiation Oncology, Städtisches Klinikum Dessau, Brandenburg Medical School Theodor Fontane, Dessau, Germany.
Adv Radiat Oncol. 2025 Mar 29;10(6):101775. doi: 10.1016/j.adro.2025.101775. eCollection 2025 Jun.
The maximal dose for partial breast irradiation (PBI) with stereotactic body radiation therapy for definitive local therapy of nonmetastatic breast cancer has not been established. Here we evaluate the maximal achievable coverage of the planning target volume suitable for PBI without violating organs-at-risk constraints.
Planning computed tomography scans of 22 patients with pulmonary or cardiac risk factors and left-sided disease in prone and supine position (sp) were obtained. Plans for PBI in 5 fractions were generated according to the Guidelines of the American Society for Radiation Oncology. Maximum tolerated dose (MTD) was defined when the dose reached any constraint of a neighboring organ based on recommendations of the American Association for Physics in Medicine.
Mean MTD was 45.9 ± 3.9 Gy (range, 38.8-53.9) in sp and 46.1 ±3.2 Gy (range, 37.3-53.9) in prone position (pp), respectively. The MTD was ≥44.3 Gy in sp and ≥44.8 Gy in pp in 95% of patients. Fat tissue was the dose limiting structure in 11 of 22 patients in sp and 15 of 22 in pp. D to the fat tissue reached 40.0 Gy (±3.3 Gy) in sp and pp. Skin was the dose limiting structure in 7 of 22 patients in sp and in 6 of 22 in pp. D to the skin was 30.5 Gy (±7.4 Gy) in sp and 31.0 Gy (±7.0 Gy) in pp ( = .8). Ribs were dose limiting in 4 of 22 patients in sp and in 1 of 22 in pp. D to the ribs was 31.4 Gy (±9.5 Gy) in sp and 21.4 Gy (±11.0 Gy) in pp ( < .01). D to the intraventricular artery was 3.4 Gy (±3.1 Gy) in sp and 7.5 Gy (±5.7 Gy) in pp ( < .01).
For definitive stereotactic body radiation therapy for early-stage breast cancer, we propose a dose escalation starting with 45 Gy in 5 fractions to be tested in a clinical trial. Prone position is advised for tumors close to the thoracic cage.
立体定向体部放射治疗用于非转移性乳腺癌的根治性局部治疗时，部分乳腺照射（PBI）的最大剂量尚未确定。在此，我们评估在不违反危及器官限制条件下，适合PBI的计划靶体积的最大可实现覆盖范围。
获取了22例有肺部或心脏危险因素且左侧患病的患者在俯卧位和仰卧位（sp）的计划计算机断层扫描图像。根据美国放射肿瘤学会指南生成5次分割的PBI计划。根据医学物理学会的建议，当剂量达到相邻器官的任何限制条件时，定义为最大耐受剂量（MTD）。
仰卧位时平均MTD为45.9±3.9 Gy（范围38.8 - 53.9），俯卧位（pp）时为46.1±3.2 Gy（范围37.3 - 53.9）。95%的患者仰卧位时MTD≥44.3 Gy，俯卧位时≥44.8 Gy。仰卧位22例患者中有11例、俯卧位22例患者中有15例脂肪组织是剂量限制结构。仰卧位和俯卧位时脂肪组织的剂量达到40.0 Gy（±3.3 Gy）。仰卧位22例患者中有7例、俯卧位22例患者中有6例皮肤是剂量限制结构。仰卧位时皮肤剂量为30.5 Gy（±7.4 Gy），俯卧位时为31.0 Gy（±7.0 Gy）（P = 0.8）。仰卧位22例患者中有4例、俯卧位22例患者中有1例肋骨是剂量限制结构。仰卧位时肋骨剂量为31.4 Gy（±9.5 Gy），俯卧位时为21.4 Gy（±11.0 Gy）（P < 0.01）。仰卧位时脑室内动脉剂量为3.4 Gy（±3.1 Gy），俯卧位时为7.5 Gy（±5.7 Gy）（P < 0.01）。
对于早期乳腺癌的根治性立体定向体部放射治疗，我们建议从45 Gy分5次分割开始进行剂量递增，并在临床试验中进行测试。对于靠近胸廓的肿瘤，建议采用俯卧位。
