A blood test that detects circulating tumor DNA (ctDNA) after surgery may help doctors identify which patients with stage III colon cancer could benefit from adding the anti-inflammatory drug celecoxib to chemotherapy, a post hoc analysis published in JAMA Oncology shows.
Researchers analyzed ctDNA samples from a subset of the CALGB (Alliance) 80702 trial, which enrolled more than 2,500 patients with resected stage III colorectal cancer. The analysis included 940 patients with available biospecimens: 173 were ctDNA positive after surgery and 767 were ctDNA negative. Patients with detectable ctDNA were at substantially higher risk of recurrence and experienced significant benefit from celecoxib added to standard chemotherapy.
Among ctDNA-positive patients, three-year disease-free survival was 41.0% for those who received celecoxib versus 22.6% for those given placebo. Five-year overall survival in the ctDNA-positive group was 61.6% with celecoxib compared with 39.9% with placebo. Patients without detectable ctDNA showed no clear benefit from the drug.
Celecoxib is a prescription nonsteroidal anti-inflammatory drug (NSAID). Inflammation is implicated in cancer progression, and prior trials have suggested NSAIDs might reduce recurrence in some patients, but results have been inconsistent. This analysis indicates ctDNA testing could identify the subset of patients who derive benefit and spare others from unnecessary treatment.
Lead author George Q. Zhang, MD, MPH, said measuring ctDNA after surgery “has the potential to change” how clinicians select patients for adjuvant NSAID therapy. Study chair Jeffrey Meyerhardt, MD, MPH, noted that while the original trial did not confirm an overall survival benefit, the post hoc analysis identified ctDNA-positive patients as a group that benefited from adding celecoxib.
The authors caution that prospective studies are needed to validate these findings before changing clinical practice. The work was supported by the National Cancer Institute, with additional support from Pfizer and Natera. The analysis is reported in JAMA Oncology as a post hoc analysis of the CALGB (Alliance)/SWOG 80702 phase 3 randomized clinical trial.
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