Dr Overman on the Potential Use of Endoscopy and ctNDA in Nonoperative GI Cancer Management

Michael J. Overman, MD, professor, Department of Gastrointestinal Medical Oncology, Division of Cancer Medicine, chair, Division of Executive Committee of the Medical Staff, The University of Texas MD Anderson Cancer Center, associate vice president of research, MD Anderson Cancer Network, discusses the potential role of endoscopy and circulating tumor DNA (ctDNA) to guide nonoperative management approaches for patients with gastrointestinal (GI) cancers.

In cancer therapy, traditional imaging modalities like CT scans, MRIs, and PET-CT scans are commonly used to assess treatment response, Overman begins. However, for luminal tumors such as colon, small bowel, or rectal cancers, accurate assessment of tumor response can be challenging due to limitations in imaging these areas, as they can be more mobile, he says. This then raises the question of whether alternative methods can provide better determination of tumor responses in localized colon settings, Overman explains.

Endoscopy, which is traditionally used for rectal cancer, has shown promise in assessing responses to immunotherapy in other luminal cancers, Overman continues. Clinical studies, including several retrospective analyses conducted at MD Anderson, have demonstrated a notable discrepancy between endoscopic responses and CT scan responses, he reports. Since the sum of lesions on CT scans cannot be zero, complete responses cannot be determined even if criteria are met, Overman explains. Moreover, residual scarring or thickening may still show up on CT scans, he adds. Alternatively, endoscopy appears to be more effective in determining the presence or absence of tumors, Overman asserts.

Another emerging approach that optimizes the utility of ctDNA involves the use of blood-based ctDNA biomarkers to guide therapeutic approaches, Overman says. Historically used in metastatic settings to detect mutations, ctDNA analysis is also being explored in the adjuvant setting to detect residual cancer in resected tumors, he details. In the neoadjuvant space, the question arises as to whether the presence or absence of ctDNA can indicate whether patients have achieved a disease response sufficient for ceasing therapy, Overman says.

Ultimately, the utilization of endoscopy and ctDNA biomarkers in assessing treatment response represents a promising avenue for improving the use of nonoperative management in luminal tumors. Further research is needed to validate these approaches and determine their efficacy in guiding treatment decisions and improving patient outcomes, Overman concludes.

Overman will be presenting more on this topic at the upcoming City of Hope Annual Advances and Innovations in Endoscopic Oncology and Multidisciplinary Gastrointestinal Cancer Care Meeting.