Benefits of daily online plan adaptation with reduced margins in neoadjuvant chemoradiotherapy for esophageal cancer

TL;DR

Daily online adaptive radiotherapy for esophageal cancer reduces radiation doses to healthy organs and improves target coverage.

Contribution

Demonstrates the feasibility and benefits of AI-assisted daily adaptive radiotherapy with reduced margins in esophageal cancer treatment.

Findings

Adaptive treatment prevented underdosing in 31 out of 230 fractions.

Adaptive treatment reduced heart and lung doses by 10% and 11%, respectively.

Adaptive treatment enabled a 24.6% median reduction in planning target volume.

Abstract

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•Emulated adaptive treatment for esophageal cancer was feasible in all 230 fractions.•Adaptive treatment prevented internal target underdosing in 31/230 fractions.•Adaptive treatment enabled a median 24.6% reduction in planning target volume.•Adaptive treatment reduced mean heart and lung dose by 10% and 11%, respectively.

Emulated adaptive treatment for esophageal cancer was feasible in all 230 fractions.

Adaptive treatment prevented internal target underdosing in 31/230 fractions.

Adaptive treatment enabled a median 24.6% reduction in planning target volume.

Adaptive treatment reduced mean heart and lung dose by 10% and 11%, respectively.

Image-guided radiotherapy (IGRT) for esophageal cancer requires large planning target volume (PTV) margins to account for interfraction variations, increasing radiation-associated side-effects. Cone-beam computed tomography-based (CBCT) online adaptive radiotherapy (oART) enables daily contour and plan adaptation, addressing anatomical changes and allowing for reduced PTV margins while ensuring target coverage. This study compared the dose-volume parameters of daily oART to non-adaptive IGRT in patients with esophageal cancer.

Ten patients with distal esophageal or gastroesophageal junction cancer who received neoadjuvant chemoradiotherapy (41.4 Gy/23 fractions) were included retrospectively. Daily IGRT CBCTs were used to emulate oART with artificial intelligence (AI)-assisted target and organs-of-interest contouring, manual edits when necessary, and adaptive re-optimization. PTV margins (Anterior-Posterior, Left-Right, Caudal-Cranial) were reduced from 5, 7, 10 mm (IGRT) to 3, 5, 5 mm (oART), respectively. Mean organs-of-interest and fraction-equivalent (FE) dose-volume metrics between delivered and adaptive plans were compared.

Compared with IGRT, oART plans significantly reduced the number of fractions with internal clinical target volume underdosing (V95% < 98%: n = 32 vs. n = 1 fraction; p = 0.002) and median hotspot dose (D0.1cm3: 106.2% vs. 103.9%; p = 0.002). Mean heart dose decreased by 10% (p = 0.037), and heart FE-V30Gy by 42% (7.3% vs. 4.3%; p = 0.002). Mean lung dose was reduced by 11% (p = 0.002), lung FE-V20Gy by 39% (4.2% vs. 2.6%; p = 0.002), and lung FE-V10Gy by 22% (24.6% vs. 19.3%; p = 0.002).

CBCT-based oART improved dose distribution in esophageal cancer by enabling PTV margin reduction, improved target coverage and superior organs-of-interest sparing. These findings encourage clinical implementation to reduce radiation-associated side-effects.

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