Pifer Phillip M, Bice Robert P, Jacobson Geraldine M, Lupinacci Kristin, Beriwal Sushil, Hazard Hannah W, Vargo John A
Department of Radiation Oncology, West Virginia University, Morgantown, West Virginia.
Department of Surgical Oncology, West Virginia University, Morgantown, West Virginia.
Adv Radiat Oncol. 2018 Sep 27;4(1):35-42. doi: 10.1016/j.adro.2018.09.008. eCollection 2019 Jan-Mar.
Variation exists in cooperative group recommendations for the dorsal border for the chest wall clinical target volume (CTV). We aimed to quantify the impact of this variation on doses to critical organs and examine patterns of chest wall recurrence relative to the pectoralis muscle.
We retrospectively assessed patterns of chest wall recurrence quantified to the recommended CTV borders for women treated between 2005 and 2017. We compared treatment plans for 5 women who were treated with left postmastectomy radiation therapy, with the chest wall contoured using varying dorsal borders for CTV: (1) Anterior pleural surface (Radiation Therapy Oncology Group), (2) anterior surface of pectoralis major (European Society for Radiotherapy and Oncology), and (3) anterior rib surface (institutional practice). Treatment plans were generated for 50 Gy in 25 fractions. Doses to organs-at-risk were compared using paired-sample tests.
Institutional patterns of chest wall recurrence were 64.7% skin and subcutaneous tissue, 23.5% both anterior to and between the pectoralis muscles, and 11.8% isolated to the tissue between the pectoralis major and minor. No chest wall recurrences were noted deep to pectoralis minor. When comparing the plans generated per the Radiation Therapy Oncology Group versus European Society for Radiotherapy and Oncology contouring guidelines, the mean lung V20Gy, heart mean dose, and left anterior descending artery mean dose were 33.5% versus 29.4% ( < .01), 5.2 Gy versus 3.2Gy ( = .02), and 27.3Gy versus 17.8Gy ( .04), respectively.
The recommended variations in the dorsal chest wall CTV border have significant impact on doses to the heart and lungs. Although our study was limited by small numbers, our institutional patterns of recurrence would support a more anterior dorsal border for the chest wall CTV consistent with older literature.
胸壁临床靶区（CTV）背侧边界的协作组推荐存在差异。我们旨在量化这种差异对关键器官剂量的影响，并研究相对于胸大肌的胸壁复发模式。
我们回顾性评估了2005年至2017年间接受治疗的女性患者，根据推荐的CTV边界量化的胸壁复发模式。我们比较了5例接受左乳房切除术后放疗的女性患者的治疗计划，其胸壁CTV的背侧边界采用不同的轮廓：（1）胸膜前表面（放射治疗肿瘤学组），（2）胸大肌前表面（欧洲放射治疗与肿瘤学会），以及（3）肋骨前表面（机构实践）。生成了25次分割、总剂量50 Gy的治疗计划。使用配对样本检验比较危及器官的剂量。
机构的胸壁复发模式为皮肤和皮下组织占64.7%，胸大肌前方和之间占23.5%，孤立于胸大肌和胸小肌之间的组织占11.8%。未发现胸小肌深层有胸壁复发。比较根据放射治疗肿瘤学组与欧洲放射治疗与肿瘤学会轮廓指南生成的计划时，平均肺V20Gy、心脏平均剂量和左前降支动脉平均剂量分别为33.5%对29.4%（P<0.01），5.2 Gy对3.2 Gy（P = 0.02），以及27.3 Gy对17.8 Gy（P<0.04）。
胸壁CTV背侧边界的推荐差异对心脏和肺部的剂量有显著影响。尽管我们的研究受样本量小的限制，但我们机构的复发模式支持与较旧文献一致的胸壁CTV更靠前的背侧边界。
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