Just got back from family spring break vacation and sincerely appreciative of the great feedback I was getting after changing the format of the blog to personal stories from the clinic and every day life as a medical oncologist. I’ll still include updates with FDA approvals or interesting topics from the current news every so often. I’d love feedback for future topics as well. Enjoy!
The Case
While working as a locum physician, I saw a patient who had recently undergone surgery for what was originally diagnosed as Stage II, high-risk sigmoid colon cancer. The tumor was locally advanced—either involving adjacent small or large bowel—but had no lymph node involvement at the time of resection.
She had already seen a prior locum oncologist who recommended adjuvant chemotherapy, and the patient had received one cycle of CAPOX. Unfortunately, she experienced significant fatigue and decided to discontinue further treatment. When I saw her, she was weeks out from that first cycle and adamant about avoiding more chemotherapy, citing quality of life concerns and hoping for a watch-and-wait approach instead.
A Decision Point: To Treat or Observe?
We had a long and thoughtful discussion about the pros and cons of further treatment. Given the high-risk nature of his Stage II disease, I explained that adjuvant chemotherapy, even with infusional 5-FU alone, could improve outcomes. But I also respected his autonomy and recognized that surveillance alone was a guideline-supported option.
To help guide the decision, I suggested checking a circulating tumor DNA (ctDNA) assay to evaluate for minimal residual disease (MRD). We both agreed it would be useful to inform his next steps.
The Turning Point
The ctDNA result came back positive—not once, but twice—with rising levels. This was no longer a theoretical risk of recurrence—this was biologic evidence of residual disease. A PET scan soon followed, revealing two PET-avid regional lymph nodes in the previous resection bed. Fortunately, no distant metastasis was seen.
This changed everything.
Initially, the patient was in denial, struggling to make sense of what these results meant. She insisted on a biopsy, which was reviewed in a multidisciplinary setting. The nodes were deemed highly suspicious for recurrence and initially considered unresectable by the local surgeon. However, I respectfully disagreed with that assessment. Given that these appeared to be regional lymph nodes and the patient was otherwise operable and without significant comorbidities, I believed the disease was potentially resectable. I encouraged the patient to seek a second opinion at a tertiary care center with colorectal surgical expertise. She did—and the surgeons there agreed with the potential for resectability, but recommended systemic chemotherapy first, followed by a restaging scan after 2–3 months with repeat ctDNA and CT CAP to determine the optimal next step.
From Resistance to Readiness
Shortly after her visit to the tertiary center, the patient called me: “I’m ready to start chemo—yesterday.”
It was an incredible shift—from someone who was adamantly against chemotherapy to someone now willing to aggressively treat his disease. Her entire perspective had changed, and that change was catalyzed by one test: ctDNA. I look at ctDNA as another tool like a radar system detecting a blip on the screen of something potentially lurking in the sky.
What If We Had Waited?
Guidelines recommend CT imaging every 6 months during surveillance. Had we followed that and waited, he may have become symptomatic or even developed unresectable or metastatic disease. The ctDNA test not only detected recurrence early, but it also provided enough clarity to shift the patient’s mindset—from passive observation to proactive treatment. A complete change in heart and mind!
Implications for Care
This case underscores the clinical utility of ctDNA in real-world practice. It influenced:
- Treatment escalation: Justifying the need for systemic therapy and potential need for another surgery.
- Patient decision-making: Empowering the patient to re-engage in care
- Surveillance strategy: Encouraging closer follow-up with periodic frequent imaging and possibly future use of ctDNA to monitor treatment response and more importantly post surgery MRD (minimal residual disease).
Key Takeaways for Providers and Patients
ctDNA is not perfect, but in cases where multiple reasonable options exist—such as observation vs. chemotherapy—it can be the tie-breaker. It is still possible to have imaging proven recurrent disease with ctdna negative test. I’ve seen this with small lung nodules, peritoneal disease and unfortunately and rarely with one patient having colorectal leptomeningeal-only disease with negative ct cap and negative ctdna.
Rising ctDNA levels should prompt early imaging and re-evaluation. Detectable and rising ctdna can potentially predate imaging evidence of recurrent disease 3-16 months. As a care provider, this can take considerable time to explain to patients and potentially create significant anxiety for patients and caretakers. There’s interest in considering these patients for clinical trials and determining whether earlier intervention can prevent recurrences and improve outcomes.
Multidisciplinary input, including referrals to high-volume surgical centers, can provide clarity and consensus. I have worked at a high volume tertiary care center to now doing locum work in a smaller community setting. It is interesting to see the thought processes from a general standpoint. It is just happenstance that I get to see this patient and know what was routine surgical resectability at my former center was not even a consideration of resection of surgery at the local center. Even the covering medical oncologist when I was off for two weeks was also convinced that surgery couldn’t be done. This demonstrates expertise is limited to what is known and available in the local area. And this is not to say that I am some all knowing physician either. I am humble enough to know that I have my limitations as well and hence why I always side with patients to consider 2nd opinions when their situations doesn’t make sense or they just need a fresh new objective opinion.
Patient counseling is critical—understanding what a positive result means and what steps to take next can change the trajectory of care. My initial impression of the patient went initially from an onerous patient trying to avoid all medical interventions to now a gun-ho, aggressive patient who wants any and all treatments to optimize his best chances long term for disease free remission!
Final Thoughts
I just happened to be in the right place at the right time to see this patient, but the impact was substantial. I’m grateful he had access to this testing—and that it helped him make a decision that will hopefully and ultimately extend his life with curative intentions.
Incorporating molecular markers like ctDNA into clinical discussions isn’t just about data. It’s about giving patients the clarity they need to make confident, informed decisions.
Disclaimer:
The clinical cases and stories shared on this blog are intended for educational and informational purposes only. All patient information has been de-identified in accordance with HIPAA regulations, and identifying details may have been modified, combined, or fictionalized to protect patient privacy. Any resemblance to actual persons, living or deceased, is purely coincidental. The views expressed are those of the author and do not represent the views of any employer, institution, or healthcare system.
About the author
Dr. Sajeve Thomas is a distinguished medical professional and a compassionate guide in the field of oncology. With over a decade of dedicated experience as a board-certified medical oncologist/internal medicine specialist, Dr. Thomas has become a trusted expert in the treatment of melanoma, sarcoma, and gastrointestinal conditions. He brings a wealth of expertise to the complex and challenging world of oncology.
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