Svensson Henrik, Lundstedt Dan, Hällje Maria, Gustafsson Magnus, Chakarova Roumiana, Karlsson Per
Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg, Sweden.
Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden.
Phys Imaging Radiat Oncol. 2019 Aug 30;11:54-60. doi: 10.1016/j.phro.2019.08.003. eCollection 2019 Jul.
BACKGROUND/PURPOSE: Tumor biology and patient smoking status have clear effects on the benefit of breast radiotherapy. This study developed treatment evaluation strategies that integrated dosimetry, tumor aggressiveness and smoking status for patients undergoing hypo-fractionated whole breast irradiation with simultaneous integrated boost.
MATERIALS/METHODS: The evaluation method Plan Quality Metrics (PQM) was adapted for breast cancer. Radiotherapy (RT) benefit was assessed for three levels of tumor aggressiveness; RT risk was estimated using mean dose to organs at risk and published Excess Relative Risk per Gy data for lung cancer and cardiac mortality for smokers and non-smokers. Risk for contralateral breast cancer was also evaluated. PQM and benefit/risk was applied to four patient groups (n = 10 each). Plans using 3D conformal radiotherapy (3DCRT), 3DCRT plus intensity-modulated radiation therapy (IMRT), 3DCRT plus volumetric modulated arc therapy (VMAT) and VMAT were evaluated for each patient.
3DCRT-IMRT hybrid planning resulted in higher PQM score (median 87.0 vs. 3DCRT 82.4, p < 0.01), better dose conformity, lower doses to the heart, lungs and contralateral breast. Survival benefit was most predominant for patients with high-risk breast cancer (>7% and >4.5% gain for non-smokers and smokers). For smokers with intermediate- or low-risk breast cancer, RT induced mortality risk dominated for all techniques. When considering the risk of local recurrence, RT benefitted also smokers (>5% and >2% for intermediate- and low-risk cancer).
PQM methodology was suggested for breast cancer radiotherapy evaluation. Further validation is needed. RT was beneficial for all patients with high risk of recurrence. A survival benefit for smokers with low or intermediate risk of recurrence could not be confirmed.
背景/目的：肿瘤生物学特性和患者吸烟状况对乳腺癌放疗的获益有明显影响。本研究制定了治疗评估策略，该策略整合了剂量测定、肿瘤侵袭性和吸烟状况，用于接受大分割全乳照射同步整合加量的患者。
材料/方法：对乳腺癌采用计划质量指标（PQM）评估方法。针对三种肿瘤侵袭性水平评估放疗获益；使用危及器官的平均剂量以及已公布的吸烟者和非吸烟者每Gy的超额相对风险数据估计肺癌和心脏死亡率的放疗风险。还评估了对侧乳腺癌风险。将PQM及获益/风险应用于四个患者组（每组n = 10）。对每位患者评估使用三维适形放疗（3DCRT）、3DCRT联合调强放疗（IMRT）、3DCRT联合容积调强弧形放疗（VMAT）和VMAT的计划。
3DCRT - IMRT混合计划导致更高的PQM评分（中位数87.0对3DCRT的82.4，p < 0.01），更好的剂量适形性，更低的心脏、肺和对侧乳腺剂量。高危乳腺癌患者的生存获益最为显著（非吸烟者和吸烟者的获益分别>7%和>4.5%）。对于中低危乳腺癌吸烟者，所有技术的放疗诱导死亡风险占主导。考虑局部复发风险时，放疗对吸烟者也有益（中低危癌症患者分别>5%和>2%）。
建议将PQM方法用于乳腺癌放疗评估。需要进一步验证。放疗对所有复发风险高的患者有益。无法证实复发风险低或中等的吸烟者有生存获益。
