(P050) Yttrium-90 Radioembolization for Unresectable, Chemorefractory Colorectal Cancer Liver Metastases in KRAS Wild-type and Mutant Patients

OncologyOncology Vol 29 No 4_Suppl_1
Volume 29
Issue 4_Suppl_1

90Y radioembolization is an effective treatment for CRCLMs in extending local control for liver-dominant metastatic disease. However, KRAS-mutant tumors may be more radioresistant to treatment.

Einsley Janowski, MD, PhD, Olga Timofeeva, PhD, Sergey Chasovskikh, PhD, Max Goldberg, Alexander Kim, MD, Filip Banovac, MD, Dalong Pang, PhD, Anatoly Dritschilo, MD, Keith Unger, MD; Georgetown University

INTRODUCTION: We report our institutional experience on the efficacy of resin-based yttrium-90 (90Y) radioembolization for the treatment of unresectable, chemorefractory colorectal cancer liver metastases (CRCLMs).

METHODS: From 2011 to 2014, a total of 51 patients underwent 90Y treatment for CRCLMs at our institution. A retrospective review was conducted for clinical outcomes, demographic information, and tumor mutation status. In 38 patients, interval imaging was available for tumor response assessment using Response Evaluation Criteria in Solid Tumors (RECIST) criteria. Serum (plasma) was prospectively collected in patients both pretreatment (n = 9) and posttreatment (n = 7), and circulating cell-free DNA (ccfDNA) concentration and integrity index were measured using quantitative PCR. DNA integrity results were validated in two patients using atomic force microscopy (AFM). 

RESULTS: Our patient population consisted of 51 patients diagnosed with colon cancer at a median age of 56 years (range: 31–85 yr). Tumor mutation information was available for 41 patients: 24 (58%) patients were KRAS mutant, 15 (37%) were KRAS wild-type, and 2 (5%) had microsatellite instability (MSI). The average survival after 90Y was 5.7 months ± 4.1 (range: 0–21 mo) in the entire cohort, with a 12-month survival of 10%. Average survival stratified by mutation status in KRAS wild-type, KRAS mutant, and MSI patients was 6 months ± 3.5, 5.29 months ± 4.86, and 5 months ± 2.83, respectively. Imaging assessment showed a partial response in 8 patients (21%), stable disease in 16 (42%), and progressive disease in 14 (37%) at a median follow-up of 2 months after treatment. Tumor local control after 90Y treatment averaged 2.17 months ± 2.97 for the entire cohort. Local control response, assessed according to tumor mutation, averaged 2.62 months ± 4.25 for KRAS wild-type, 1.16 months ± 1.43 for KRAS mutant, and 4.5 months ± 3.54 for MSI patients. ccfDNA was detected in 100% of the analyzed samples. Median pretreatment plasma ccfDNA levels of 4.6 ng/mL decreased to 1.8 ng/mL after single-lobe treatment. DNA integrity index was reduced from a median of 0.62 to 0.23 after treatment. Analysis by AFM of paired pre- and posttreatment samples of a KRAS-mutant patient and an MSI patient revealed minimal change in the KRAS sample but a 35% average fragment size drop in the MSI sample.

CONCLUSIONS:90Y radioembolization is an effective treatment for CRCLMs in extending local control for liver-dominant metastatic disease. However, KRAS-mutant tumors may be more radioresistant to treatment.

Proceedings of the 97th Annual Meeting of the American Radium Society- americanradiumsociety.org

Articles in this issue

(P005) Ultrasensitive PSA Identifies Patients With Organ-Confined Prostate Cancer Requiring Postop Radiotherapy
(P001) Disparities in the Local Management of Breast Cancer in the United States According to Health Insurance Status
(P002) Predictors of CNS Disease in Metastatic Melanoma: Desmoplastic Subtype Associated With Higher Risk
(P003) Identification of Somatic Mutations Using Fine Needle Aspiration: Correlation With Clinical Outcomes in Patients With Locally Advanced Pancreatic Cancer
(P004) A Retrospective Study to Assess Disparities in the Utilization of Intensity-Modulated Radiotherapy (IMRT) and Proton Therapy (PT) in the Treatment of Prostate Cancer (PCa)
(S001) Tumor Control and Toxicity Outcomes for Head and Neck Cancer Patients Re-Treated With Intensity-Modulated Radiation Therapy (IMRT)-A Fifteen-Year Experience
(S003) Weekly IGRT Volumetric Response Analysis as a Predictive Tool for Locoregional Control in Head and Neck Cancer Radiotherapy 
(S004) Combination of Radiotherapy and Cetuximab for Aggressive, High-Risk Cutaneous Squamous Cell Cancer of the Head and Neck: A Propensity Score Analysis
(S005) Radiotherapy for Carcinoma of the Hypopharynx Over Five Decades: Experience at a Single Institution
(S002) Prognostic Value of Intraradiation Treatment FDG-PET Parameters in Locally Advanced Oropharyngeal Cancer
(P006) The Role of Sequential Imaging in Cervical Cancer Management
(P008) Pretreatment FDG Uptake of Nontarget Lung Tissue Correlates With Symptomatic Pneumonitis Following Stereotactic Ablative Radiotherapy (SABR)
(P009) Monte Carlo Dosimetry Evaluation of Lung Stereotactic Body Radiosurgery
(P010) Stereotactic Body Radiotherapy for Treatment of Adrenal Gland Metastasis: Toxicity, Outcomes, and Patterns of Failure
(P011) Stereotactic Radiosurgery and BRAF Inhibitor Therapy for Melanoma Brain Metastases Is Associated With Increased Risk for Radiation Necrosis
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