Hoekstra Nienke, Habraken Steven, Swaak-Kragten Annemarie, Breedveld Sebastiaan, Pignol Jean-Philippe, Hoogeman Mischa
Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, Netherlands.
Department of Radiotherapy, Dalhousie University, Halifax, NS, Canada.
Front Oncol. 2020 Aug 18;10:1445. doi: 10.3389/fonc.2020.01445. eCollection 2020.
Adjuvant accelerated partial breast irradiation (APBI) results in low local recurrence risks. However, the survival benefit of adjuvant radiotherapy APBI for low-risk breast cancer might partially be offset by the risk of radiation-induced lung cancer. Reducing the lung dose mitigates this risk, but this could result in higher doses to the ipsilateral breast. Different external beam APBI techniques are equally conformal and homogenous, but the intermediate to low dose distribution differs. Thus, the risk of toxicity is different. The purpose of this study is to quantify the trade-off between secondary lung cancer risk and breast dose in treatment planning and to compare an optimal coplanar and non-coplanar technique. A total of 440 APBI treatment plans were generated using automated treatment planning for a coplanar VMAT beam-setup and a non-coplanar robotic stereotactic radiotherapy beam-setup. This enabled an unbiased comparison of two times 11 Pareto-optimal plans for 20 patients, gradually shifting priority from maximum lung sparing to maximum ipsilateral breast sparing. The excess absolute risks of developing lung cancer and breast fibrosis were calculated using the Schneider model for lung cancer and the Avanzo model for breast fibrosis. Prioritizing lung sparing reduced the mean lung dose from 2.2 Gy to as low as 0.3 Gy for the non-coplanar technique and from 1.9 Gy to 0.4 Gy for the coplanar technique, corresponding to a 7- and 4-fold median reduction of secondary lung cancer risk, respectively, compared to prioritizing breast sparing. The increase in breast dose resulted in a negligible 0.4% increase in fibrosis risk. The use of non-coplanar beams resulted in lower secondary cancer and fibrosis risks ( < 0.001). Lung sparing also reduced the mean heart dose for both techniques. The risk of secondary lung cancer of external beam APBI can be dramatically reduced by prioritizing lung sparing during treatment planning. The associated increase in breast dose did not lead to a relevant increase in fibrosis risk. The use of non-coplanar beams systematically resulted in the lowest risks of secondary lung cancer and fibrosis. Prioritizing lung sparing during treatment planning could increase the overall survival of early-stage breast cancer patients by reducing mortality due to secondary lung cancer and cardiovascular toxicity.
辅助性加速部分乳腺照射（APBI）导致局部复发风险较低。然而，辅助性放疗APBI对低风险乳腺癌的生存获益可能会部分被放射性肺癌的风险所抵消。降低肺部剂量可减轻这种风险，但这可能会导致同侧乳腺接受更高剂量的照射。不同的外照射APBI技术具有相同的适形性和均匀性，但中低剂量分布有所不同。因此，毒性风险也不同。本研究的目的是在治疗计划中量化继发性肺癌风险与乳腺剂量之间的权衡，并比较最优的共面和非共面技术。使用自动治疗计划为共面VMAT射束设置和非共面机器人立体定向放射治疗射束设置生成了总共440个APBI治疗计划。这使得能够对20例患者的两组11个帕累托最优计划进行无偏比较，逐渐将优先级从最大程度的肺部保护转移到最大程度的同侧乳腺保护。使用Schneider肺癌模型和Avanzo乳腺纤维化模型计算发生肺癌和乳腺纤维化的超额绝对风险。与优先保护乳腺相比，优先保护肺部可使非共面技术的平均肺部剂量从2.2 Gy降低至低至0.3 Gy，共面技术的平均肺部剂量从1.9 Gy降低至0.4 Gy，继发性肺癌风险的中位数分别降低7倍和4倍。乳腺剂量的增加导致纤维化风险仅可忽略不计地增加0.4%。使用非共面射束导致较低的继发性癌症和纤维化风险（<0.001）。保护肺部也降低了两种技术的平均心脏剂量。通过在治疗计划中优先保护肺部，外照射APBI的继发性肺癌风险可显著降低。乳腺剂量的相关增加并未导致纤维化风险的显著增加。使用非共面射束系统性地导致最低的继发性肺癌和纤维化风险。在治疗计划中优先保护肺部可通过降低继发性肺癌和心血管毒性导致的死亡率来提高早期乳腺癌患者的总生存率。
