Mohiuddin Jahan J, Jethwa Krishan R, Grandhi Nikhil, Breen William G, Wang Xingmei, Anvari Akbar, Lin Hui, Sandhyavenu Harigopal, Doucette Abigail, Plastaras John P, Rule William G, Metz James M, Merrell Kenneth W, Sio Terence T, Ashman Jonathan B, Haddock Michael G, Ben-Josef Edgar, Hallemeier Christopher L, Wojcieszynski Andrzej P
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
Department of Therapeutic Radiology, Yale University, New Haven, Connecticut.
Adv Radiat Oncol. 2021 Jun 24;6(5):100744. doi: 10.1016/j.adro.2021.100744. eCollection 2021 Sep-Oct.
Concurrent chemoradiation therapy is a curative treatment for squamous cell carcinoma of the anus, but patients can suffer from significant treatment-related toxicities. This study was undertaken to determine whether intensity modulated proton therapy (IMPT) is associated with less acute toxicity than intensity modulated radiation therapy (IMRT) using photons.
We performed a multi-institutional retrospective study comparing toxicity and oncologic outcomes of IMRT versus IMPT. Patients with stage I-IV (for positive infrarenal para-aortic or common iliac nodes only) squamous cell carcinoma of the anus, as defined by the American Joint Committee on Cancer's , eighth edition, were included. Patients with nonsquamous histology or mixed IMPT and IMRT treatment courses were excluded. Acute nonhematologic toxicities, per the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE), version 4, were recorded prospectively at all sites. Acute and late toxicities, dose metrics, and oncologic outcomes were compared between IMRT and IMPT using univariable and multivariable statistical methods. To improve the robustness of our analysis, we also analyzed the data using propensity score weighting methods.
A total of 208 patients were treated with either IMPT (58 patients) or IMRT (150 patients). Of the 208 total patients, 13% had stage I disease, 36% stage II, 50% stage III, and 1% stage IV. IMPT reduced the volume of normal tissue receiving low-dose radiation but not high-dose radiation to bladder and bowel. There was no significant difference between treatment groups in overall grade 3 or greater acute toxicity (IMRT, 68%; IMPT, 67%; = .96) or 2-year overall grade 3 or greater late toxicity (IMRT, 3.5%; IMPT, 1.8%; = .88). There was no significant difference in 2-year progression-free survival (hazard ratio, 0.8; 95% CI, 0.3-2.0).
Despite reducing the volume of normal tissue receiving low-dose radiation, IMPT was not associated with decreased grade 3 or greater acute toxicity as measured by CTCAE. Additional follow-up is needed to assess whether important differences arise in late toxicities and if further prospective evaluation is warranted.
同步放化疗是肛管鳞状细胞癌的一种根治性治疗方法，但患者可能会遭受与治疗相关的严重毒性反应。本研究旨在确定调强质子治疗（IMPT）与使用光子的调强放射治疗（IMRT）相比，是否具有更低的急性毒性。
我们进行了一项多机构回顾性研究，比较IMRT与IMPT的毒性和肿瘤学结局。纳入美国癌症联合委员会第八版定义的I-IV期（仅适用于肾下主动脉旁或髂总淋巴结阳性）肛管鳞状细胞癌患者。排除非鳞状组织学患者或接受IMPT和IMRT混合治疗疗程的患者。根据美国国立癌症研究所不良事件通用术语标准（CTCAE）第4版，前瞻性记录所有部位的急性非血液学毒性。使用单变量和多变量统计方法比较IMRT和IMPT之间的急性和晚期毒性、剂量指标及肿瘤学结局。为提高分析的稳健性，我们还使用倾向评分加权方法分析数据。
共有208例患者接受了IMPT（58例）或IMRT（150例）治疗。在这208例患者中，13%为I期疾病，36%为II期，50%为III期，1%为IV期。IMPT减少了接受低剂量辐射的正常组织体积，但未减少膀胱和肠道接受高剂量辐射的体积。治疗组之间在总体3级或更高急性毒性（IMRT，68%；IMPT，67%；P = 0.96）或2年总体3级或更高晚期毒性（IMRT，3.5%；IMPT，1.8%；P = 0.88）方面无显著差异。2年无进展生存率无显著差异（风险比，0.8；95%可信区间，0.3 - 2.0）。
尽管IMPT减少了接受低剂量辐射的正常组织体积，但根据CTCAE测量，IMPT与3级或更高急性毒性的降低无关。需要进一步随访以评估晚期毒性是否出现重要差异以及是否有必要进行进一步的前瞻性评估。
