@california14 - Facing stage 3b colon cancer is tough, and it’s understandable to feel frustrated that your oncologists at an NCI-designated cancer center aren’t using the Signatera ctDNA test, especially given its reported 88% sensitivity for detecting colorectal cancer recurrence. Studies like the GALAXY arm of CIRCULATE-Japan show Signatera’s ability to predict recurrence risk and guide adjuvant chemotherapy, with ctDNA-positive patients at higher risk (HR 10.82). These studies show that the most important test is 30 days post-surgery to check for any residual disease. However, some oncologists hesitate due to rare false positives (1.9% spontaneous clearance) or ongoing trials (e.g., CIRCULATE-US) refining its role.

Your proactive advocacy is powerful—self-education is key. Ask your oncologist why they don’t use Signatera, is it because they consider your CRC is considered low risk? Is CT DNA testing not typically part of the treatment plan? Remember Signatera is not the only CTDNA test available, Oncodetect from Exact Sciences, and Guardant 360 are also utilized by many institutions. Would you like more information about these to discuss with your oncology team?

Request clarity on their surveillance plan (e.g., CEA, CT scans) and if ctDNA could complement it. Cancer care can feel unpredictable, but your voice matters. Consider a second opinion from another NCI center or ask to discuss trials like DYNAMIC-III to explore ctDNA-guided care. You’re not alone—keep asking questions, and lean on support groups for strength.