Dose coverage comparison between "interstitial catheter-only" and "hybrid intracavitary-interstitial brachytherapy" for early stage squamous cell carcinoma of the buccal mucosa

Naoya Murakami; Takao Ueno; Wakako Yatsuoka; Hiroyuki Okamoto; Nikolaos Tselis; Koji Masui; Ken Yoshida; Kana Takahashi; Koji Inaba; Kae Okuma; Hiroshi Igaki; Yuko Nakayama; Jun Itami

doi:10.5114/jcb.2018.79471

Dose coverage comparison between "interstitial catheter-only" and "hybrid intracavitary-interstitial brachytherapy" for early stage squamous cell carcinoma of the buccal mucosa

J Contemp Brachytherapy. 2018 Oct;10(5):486-491. doi: 10.5114/jcb.2018.79471. Epub 2018 Oct 31.

Authors

Affiliations

¹ Department of Radiation Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
² Department of Oral Health and Diagnostic Sciences, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
³ Department of Radiotherapy and Oncology, Goethe-University Hospital, Goethe-University Frankfurt, Germany.
⁴ Department of Radiology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
⁵ Department of Radiation Oncology, Osaka Medical College, Takatsuki, Osaka, Japan.

Abstract

Purpose: When squamous cell carcinoma of the buccal mucosa (BSCC) extends surrounding anatomical sites such as gingiva, retromolar triangle, or hard palate, it might be challenging to ensure adequate tumor coverage by sole interstitial brachytherapy due to the complexity of catheter implantation. By combining interstitial catheters with an enoral placed, individually assembled "oral spacer plus embedded catheters" device (hybrid of intracavitary-interstitial brachytherapy), it should be easier to deliver the necessary tumoricidal dose to irregular-shaped tumor volumes (clinical target volume - CTV) with improved conformity. The purpose of this analysis was to compare the dose distribution created by the hybrid of intracavitary-interstitial brachytherapy (HBT) with the dose distribution of an interstitial catheter only-approach, based on the interstitial catheters used for HBT (ISBT-only) by evaluating respective treatment plans (HBT plan vs. ISBT-only plan) for the treatment of early stage BSCC.

Material and methods: A retrospective analysis was performed for patients with localized BSCC treated between April 2013 and October 2017. All patients received sole HBT without additional external beam radiation therapy or planned neck dissection. Dosimetric parameters taken into account for comparison between actual HBT and virtual ISBT-only were CTV D₉₀, CTV V₁₀₀, CTV V₁₅₀, CTV V₂₀₀, mandible D_2cc, and mucosal surface D_2cc.

Results: Dosimetrically, HBT showed a trend toward better CTV D₉₀ compared to ISBT-only. In addition, HBT demonstrated statistically better CTV V₁₀₀ coverage compared to ISBT-only. There was no statistically significant difference with respect to CTV V₁₅₀, CTV V₂₀₀, and mucosal surface D_2cc, while a trend was seen in better mandible D_0.1cc between HBT and ISBT-only.

Conclusions: The HBT approach appears to enable improved dose coverage of irregular-shaped enoral tumor volumes compared to ISBT-only for patients with early stage BSCC.

Keywords: brachytherapy; buccal mucosa; hybrid; interstitial brachytherapy; squamous cell carcinoma.

Publication types

Case Reports