Photon mini-GRID therapy for preoperative breast cancer tumor treatment: A treatment plan study

IF 3.2 2区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Medical physics Pub Date : 2025-01-28 DOI:10.1002/mp.17634

Angela Corvino, Tim Schneider, Jeremi Vu-Bezin, Pierre Loap, Youlia Kirova, Yolanda Prezado

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引用次数: 0

Abstract

Background

Breast cancer is the leading cause of female cancer mortality worldwide, accounting for 1 in 6 cancer deaths. Surgery, radiation, and systemic therapy are the three pillars of breast cancer treatment, with several strategies developed to combine them. The association of preoperative radiotherapy with immunotherapy may improve breast cancer tumor control by exploiting the tumor radio-induced immune priming. However, this requires the use of hypofractionated radiotherapy (3 × 8 Gy), increasing the risk of toxicity. Mini-GRID therapy (mini-GRT) is an innovative form of spatially fractionated radiation therapy (SFRT) characterized by narrow beam widths between 1 to 2 mm that promises a significant increase in normal tissue dose tolerances and could thereby represent a new alternative for preoperative breast cancer treatment. Mini-GRT has been successfully implemented at the Hospital de Santiago de Compostela (Spain) with a flattening filter-free LINAC (megavoltage x-rays).

Purpose

In this dosimetry proof-of-concept study, we evaluate the feasibility of photon mini-GRT for preoperative breast cancer treatment. We also assess the clinical potential of mini-GRT and compare it with the current treatment standard of intensity-modulated radiotherapy (IMRT).

Methods

Seven unbiased breast cancer dosimetries of patients treated with stereotactic body radiotherapy (SBRT) (3 × 8 Gy, IMRT) were selected for the study. Photon mini-GRT was compared with SBRT using three main criteria: (i) the dose to organs at risk (OARs), (ii) the dose constraints dictated by normal tissue tolerance, and (iii) the lateral penumbra in OARs. Tumor coverage was evaluated in terms of normalized total dose at 8 Gy-fractions. The optimized SBRT by IMRT was realized at the Institut Curie, Paris, France. The dose in mini-GRT was calculated by means of Monte Carlo simulations based on the mini-GRT implementation realized at the University Hospital in Santiago de Compostela.

Results

Compared to SBRT plans, mini-GRT resulted in a reduction of the mean dose to the lungs, heart, chest wall, and lymph nodes in the studied cases by a factor ranging from 50% to 100%. Additionally, valley, mean, and peak doses to normal tissues meet the dose tolerance limits for the considered OARs, the most challenging of all being the skin. The mean dose to the skin was reduced (20%–60% less) for most of the studied cases. Mini-GRT also yielded sharper lateral penumbras in the skin and lungs (size reduced by at least 50%). Similar tumor integral doses were obtained for the two treatment modalities.

Conclusion

Mini-GRT with megavoltage x-rays is an innovative treatment approach already implemented in a clinical context. In this proof-of-concept study, we evaluated mini-GRT for partial breast cancer irradiation, demonstrating its potential for preoperative treatment thanks to the high skin and normal tissue-sparing capabilities. These initial results represent a first step towards clinical use and encourage further prospective clinical studies.

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光子微栅格治疗乳腺癌术前肿瘤：一项治疗方案研究。

背景：乳腺癌是全球女性癌症死亡的主要原因，占癌症死亡人数的六分之一。手术、放疗和全身治疗是乳腺癌治疗的三大支柱，有几种策略将它们结合起来。术前放疗与免疫治疗的结合可能通过利用肿瘤放射诱导的免疫启动来改善乳腺癌肿瘤控制。然而，这需要使用低分割放疗（3 × 8 Gy），增加了毒性风险。Mini-GRID治疗（mini-GRT）是一种创新的空间分割放射治疗（SFRT）形式，其特点是狭窄的光束宽度在1至2毫米之间，有望显著增加正常组织的剂量耐受性，因此可能代表术前乳腺癌治疗的新选择。Mini-GRT已在圣地亚哥德孔波斯特拉医院（西班牙）成功实施，采用无压平滤波器的LINAC（超高电压x射线）。目的：在这个剂量学概念验证研究中，我们评估光子微型grt用于乳腺癌术前治疗的可行性。我们还评估了mini-GRT的临床潜力，并将其与目前的调强放疗（IMRT）治疗标准进行了比较。方法：选取7例接受立体定向体放疗（SBRT）（3 × 8 Gy， IMRT）的无偏倚乳腺癌患者进行剂量测定。使用三个主要标准将Photon mini-GRT与SBRT进行比较：(i)危及器官的剂量（OARs），（ii）正常组织耐受决定的剂量限制，（iii） OARs的外侧半暗带。肿瘤覆盖率根据8个gy分数的标准化总剂量进行评估。通过IMRT优化的SBRT在法国巴黎居里研究所实现。在圣地亚哥德孔波斯特拉大学医院实现的mini-GRT的基础上，通过蒙特卡罗模拟计算mini-GRT的剂量。结果：与SBRT计划相比，mini-GRT导致研究病例中肺、心脏、胸壁和淋巴结的平均剂量减少50%至100%。此外，对正常组织的谷值、平均和峰值剂量符合所考虑的桨的剂量耐受限制，其中最具挑战性的是皮肤。对于大多数研究病例，皮肤的平均剂量减少了（减少了20%-60%）。Mini-GRT在皮肤和肺部也显示出更清晰的外侧半影（大小减少至少50%）。两种治疗方式获得了相似的肿瘤整体剂量。结论：超高压x射线的Mini-GRT是一种创新的治疗方法，已经在临床中实施。在这项概念验证性研究中，我们评估了mini-GRT对部分乳腺癌的照射，由于其高度的皮肤和正常组织保护能力，证明了其在术前治疗中的潜力。这些初步结果代表了临床应用的第一步，并鼓励进一步的前瞻性临床研究。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Medical physics 医学-核医学

CiteScore

6.80

自引率

15.80%

发文量

660

审稿时长

1.7 months

期刊介绍： Medical Physics publishes original, high impact physics, imaging science, and engineering research that advances patient diagnosis and therapy through contributions in 1) Basic science developments with high potential for clinical translation 2) Clinical applications of cutting edge engineering and physics innovations 3) Broadly applicable and innovative clinical physics developments Medical Physics is a journal of global scope and reach. By publishing in Medical Physics your research will reach an international, multidisciplinary audience including practicing medical physicists as well as physics- and engineering based translational scientists. We work closely with authors of promising articles to improve their quality.