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Natera's GALAXY Study update, which explores the critical role of circulating tumor DNA (ctDNA) in predicting colorectal cancer outcomes. Utilizing Natera's Signatera test, the study tracked over 2,200 patients with stage 2 to stage 4 colorectal cancer, revealing how ctDNA status serves as a powerful prognostic factor for disease recurrence and overall survival.
Key Findings:
Study Design: The study included 2,240 colorectal cancer patients, followed for a median of 23 months, with 1,791 patients included in the disease-free survival analysis and 1,794 in the overall survival analysis.
ctDNA-Positive Results: 15.6% of patients tested positive for ctDNA, with a recurrence rate of 78%. Their disease-free survival rate was only 20% at 24 months and 17% at 36 months. At 24 months, overall survival for ctDNA-positive patients was 84%, dropping to 72% by 36 months.
ctDNA-Negative Results: 84.4% of patients were ctDNA-negative, with a much lower recurrence rate of 13%. Their disease-free survival remained strong at 85% at 24 months and 84% at 36 months. Overall survival was 99% at 24 months and 96% at 36 months.
Prognostic Power: ctDNA status was identified as the strongest prognostic factor in both disease-free and overall survival. In particular, Signatera-positive patients were 34 times more likely to experience recurrence compared to ctDNA-negative patients.
Other factors influencing outcomes included:
Genetic Mutations: Mutations like BRAF V600E and RAS were linked to worse survival outcomes.
Lymph Node Status: Lymph node positivity was also associated with poor disease-free and overall survival.
Clinical Implications:
For ctDNA-negative patients, observation may be sufficient, potentially allowing some to avoid chemotherapy.
ctDNA-positive patients may require additional treatment, such as adjuvant chemotherapy, to reduce the risk of recurrence.
Looking ahead, randomized trials, like the CIRCULATE-Japan Vega Protocol, are underway to explore the de-escalation or omission of chemotherapy for ctDNA-negative patients.
Additionally, ctDNA shows promise as a surrogate endpoint in drug approval trials, which could change how cancer therapies are evaluated in the future.
Source Material Used for This Video: www.natera.com/company/news/first-of-its-kind-colorectal-cancer-data-from-prospective-galaxy-study-released-at-esmo-demonstrates-signateras-ability-to-predict-overall-survival/