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Review
. 2022 May 7;14(9):2318.
doi: 10.3390/cancers14092318.

Optimal Clinical Target Volume of Radiotherapy Based on Microscopic Extension around the Primary Gross Tumor in Non-Small-Cell Lung Cancer: A Systematic Review

Yukihisa Tamaki  1   2 , Norihiro Aibe  3 , Takafumi Komiyama  2   4 , Satoshi Nagasaka  5 , Toshiyuki Imagumbai  6 , Tomoko Itazawa  7 , Hiroshi Onishi  2   4 , Tetsuo Akimoto  2   8 , Yasushi Nagata  2   9 , Yuko Nakayama  2   10
Affiliations
Review

Optimal Clinical Target Volume of Radiotherapy Based on Microscopic Extension around the Primary Gross Tumor in Non-Small-Cell Lung Cancer: A Systematic Review

Yukihisa Tamaki et al. Cancers (Basel). .

Abstract

A crucial issue in radical radiation therapy for non-small-cell lung cancer is how to define the clinical target volume (CTV). Although the scope of microscopic extension (ME) and microscopic proximal bronchial extension (PBE) from a primary tumor should be considered when defining the CTV, there has been limited research on ME and PBE. Therefore, we conducted this systematic review. The PubMed, ICHUSHI (Japanese database), and Cochrane Library databases were searched, and 816 articles were initially retrieved. After primary and secondary screenings, eight articles were ultimately selected. The results of this systematic review suggest the importance of a 0 mm margin in stereotactic radiotherapy for early-stage cancer and a 5-8 mm margin in curative irradiation for locally advanced cancer. Regarding PBE, this review yielded the conclusion that it is appropriate to consider the addition of an approximately 15 mm margin from the bronchial vasculature. Although there were few articles with a high level of evidence, this systematic review enabled us to collate results from previous studies and to provide recommendations, to some extent, regarding the CTV margin in the current clinical environment, where high-precision radiation therapy, such as image-guided radiotherapy and intensity-modulated radiotherapy, is predominant.

Keywords: gross tumor volume; non-small-cell lung cancer; radiation therapy; systematic review.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
A schematic figure illustrating the GTV-to-CTV margin for ME into the lung parenchyma. GTV, gross tumor volume; CTV, clinical target volume; ME, microscopic extension.
Figure 2
Figure 2
A schematic figure illustrating the GTV-to-CTV margin for microscopic PBE. GTV, gross tumor volume; CTV, clinical target volume; PBE, proximal bronchial extension.
Figure 3
Figure 3
Flowchart of this systematic review.
See this image and copyright information in PMC

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