Phase II Study of Stereotactic Body Radiation Therapy (SBRT) in Patients with Lung and/or Liver Oligometastases from Colorectal Cancer (CRC): KRAS Gene Status and Metastatic Site Matter

Abstract

<h3>Purpose/Objective(s)</h3> To evaluate the local control in patients with lung and/or liver oligometastases from CRC, and explore whether KRAS gene status and other prognostic factors could influence local control. <h3>Materials/Methods</h3> This prospective, single-arm, open-label, phase II clinical trial (NCT02909114) included patients who had histologically proven CRC, with controlled primary tumor and extra-hepatic/pulmonary lesions, 1-5 inoperable liver and/or lung metastases with maximum diameter ≤5cm. The primary endpoint was 3-year local control (LC). The secondary endpoints were radiation-related toxicities, overall survival (OS) and progression-free survival (PFS). <h3>Results</h3> Between January 2016 and December 2019, 48 patients with 60 metastases in our institution were enrolled. The overall median follow-up period was 42.8 months (range: 3.0–60.9 months)<b>,</b> median tumor size was 1.3cm (range: 0.6–5 cm), dose of 35-70Gy in 3-10fractions was administered to the PTV and median BED was 100Gy. The 1-year and 3-year LC rates were 88.3% (95%CI 80.1-96.5%) and 65.9% (95%CI 53.1-78.7%), respectively. KRAS gene status, the site of metastases, PTV volume and time to metastases were the four independent prognostic parameters in the multivariate analysis. No patients developed toxicities of grade 3 or above. <h3>Conclusion</h3> SBRT as a competitive treatment for patients with lung and/or liver oligometastases from CRC, revealing a favorable LC and mild toxicity. The prognostic parameters may contribute to appropriate decision-making.