Current Status (as of Jan 15, 2026)

• NED on imaging: MRI abdomen shows post-surgical changes only, no new hepatic lesions. CT chest: stable pulmonary nodules (9 mm RLL, stable >15 months).
• CEA 1.8 (Siteman, 01/15) — approaching baseline of 1.4 from initial diagnosis (11/2021). Lowest value since treatment began.
• Labs completely normal: CBC, CMP, LFTs all within range. Creatinine 1.16 (eGFR 77). Platelets recovered to 170 (from nadir of 131 on chemo).
• ECOG 0 — fully active, no symptoms.
• Guardant 360 MRD: NEGATIVE — no circulating tumor DNA detected.
• Guardant Tissue: NEGATIVE — tumor-informed ctDNA assay also negative.

The Decision Point

At our Jan 15 visit, Dr. Tan outlined three options:

1. Observation — frequent CEA and scans
2. “Adjuvant” chemotherapy — 5-FU-based
3. FOLFOX + panitumumab — given RAS wild-type status and possible lung metastasis

We agreed to await the Guardant results before deciding. The results are now back: negative for both assays.

Why I Still Want to Discuss Escalation

The ctDNA-negative result is genuinely good news. But my clinical history gives me pause about relying on surveillance alone:

• Two recurrences — the second came while on active 5-FU maintenance (Nov 2025 MRI showed new liver lesions during cycle 7-8 of 5-FU)
• First liver resection had a positive margin (segment 2, May 2025)
• CEA was unreliable — it was falling (3.3 → 2.6) while new metastases were forming. And at initial diagnosis, CEA was only 1.4 with a pT4 tumor.
• Disease escaped maintenance therapy — 5-FU alone has empirically failed to prevent recurrence in my case

The negative ctDNA shifts the calculus but doesn’t resolve it. The false-negative rate is 5-15%, and may be higher for tumors with low ctDNA shedding — which mine may be, given the consistently low CEA pattern.

What I’d Like to Discuss

On treatment strategy:

• Given my recurrence history, does the ctDNA-negative result change your recommendation? Or does the clinical pattern still warrant some form of treatment?
• At our last visit you mentioned FOLFOX/panitumumab as option 3. Anti-EGFR therapy has never been used in my case — is this the right time to deploy it?
• Would a middle path make sense? For example, 5-FU/LV + panitumumab (no oxaliplatin initially), with serial ctDNA monitoring — escalating to full FOLFOX only if ctDNA turns positive?
• If we do use oxaliplatin, can we use a stop-and-go approach (4-6 cycles then maintenance without oxaliplatin)?

On colonoscopy surveillance:

• I received a call from Anderson about a colonoscopy being due. My last full colonoscopy was the diagnostic scope in November 2021 (sigmoid mass found), and the July 2024 hemicolectomy included intraoperative bowel evaluation. Is now the right time, or should we coordinate timing with any planned treatment?
• Would you prefer I have the colonoscopy done at Siteman so your team can review the findings directly, or is Anderson fine?
• If we’re starting systemic therapy, does the timing of the colonoscopy need to fit around the treatment schedule?

On monitoring:

• How often should we repeat the Guardant liquid biopsy? Every 8 weeks? 12 weeks?
• Given that CEA failed to detect my November recurrence, should ctDNA and imaging be the primary surveillance tools going forward?

On the lung nodules:

• With 15+ months of stability, no FDG uptake, and the histoplasmosis belt context — is the diagnostic wedge resection still on the table, or has time settled the question?
• If we start systemic therapy, would response (or lack thereof) in the lung nodules serve as a diagnostic test?

On long-term strategy:

• If I achieve sustained molecular clearance through a course of treatment, what’s the threshold for stopping?
• Any relevant clinical trials at Siteman for MSS mCRC? (botensilimab/balstilimab, bispecifics, adaptive ctDNA-guided therapy)

Where My Head Is

My priority is more time. I’ve had two recurrences, and the second one came through on active treatment. I don’t want to look back and wish we had been more aggressive during this window when the disease burden is at its lowest.

I’m willing to deal with side effects — including oxaliplatin neuropathy — if you believe the benefit is there. But I also trust your judgment on which regimen gives me the best risk-adjusted benefit. If you think panitumumab without oxaliplatin is the smarter play right now, I’m open to that too.

The key thing: I don’t want observation alone. This disease has shown it can recur silently and quickly.

Key Facts for Quick Reference