Extending hypofractionated stereotactic body radiotherapy to tumours larger than 70cc – effects and side effects

Stereotactic body radiotherapy (SBRT) for tumours ≥5 cm is poorly studied and its utility and feasibility is uncertain. We here report the Karolinska experience of SBRT in this setting. All patients had a gross tumour volume (GTV) ≥70 cc, a prescribed physical dose of at least 40 Gy and received treatment between 1995–2012. We included 164 patients with 175 tumours located in the thorax (<i>n</i> = 86), the liver (<i>n</i> = 27) and the abdomen (<i>n</i> = 62) and treated with a median prescribed dose (BED_{α/β 10Gy}) of 80 Gy (71.4–113). One- and 2- year local control rates were 82% and 61%. In multivariate analyses, minimum dose to the GTV and histological subtype were associated with local control. Renal cell carcinoma (RCC) histology showed the most favourable local control − 94% at 2 years for all histologies. Thirty-seven patients experienced grade 3–5 toxicity most likely related to SBRT. Seven of the ten patients with grade 5 toxicity, had a centrally located tumour in the thorax. SBRT of tumours &gt;5 cm in diameter may be an option for peripherally located lung and abdominal tumours. Histological origin and tumour location should be considered before treatment.

针对直径≥5cm肿瘤的立体定向体部放射治疗（Stereotactic Body Radiotherapy, SBRT）相关研究尚少，其临床应用价值与可行性尚未明确。本文报告卡罗林斯卡医学院在此类场景下应用SBRT的诊疗经验。本研究纳入1995年至2012年间接受治疗的所有大体肿瘤体积（Gross Tumour Volume, GTV）≥70cm³、处方物理剂量至少40Gy的患者。共纳入164例患者，共计175个肿瘤，其中胸部肿瘤86个（n=86）、肝脏肿瘤27个（n=27）、腹部肿瘤62个（n=62）；患者的中位处方生物等效剂量（BED_α/β=10Gy）为80Gy（四分位间距71.4~113）。1年和2年局部控制率分别为82%与61%。多因素分析结果显示，GTV的最低受照剂量与组织学亚型与局部控制显著相关。其中肾细胞癌（Renal Cell Carcinoma, RCC）组织学类型的局部控制效果最优，该亚型患者的2年局部控制率达94%。37例患者出现了与SBRT高度相关的3~5级毒性反应，在10例发生5级毒性反应的患者中，有7例为胸部中央型肿瘤。对于外周型肺与腹部肿瘤，直径＞5cm的肿瘤采用SBRT治疗或为可选方案，治疗前应综合考量肿瘤的组织学来源与部位。