EPD100 - Effectiveness of MRI and endoscopy in the detection of local regrowth of rectal cancer during Watch-and-Wait management

ePoster of Distinction Presenter(s)

• 

  Sudheer Vemuru, MD

  Resident
  University of Colorado School of Medicine, Department of Surgery
  University of Colorado Anschutz Medical Center
  Aurora, CO, United States

  All of the relevant financial relationships listed below have been mitigated.
  This individual has no financial relationships with ineligible companies.

Author(s)

• 

  Samuel H. Lai, MD

  Resident
  University of Colorado School of Medicine, Department of Surgery
  University of Colorado School of Medicine
  Aurora, CO, United States

  Disclosure information not submitted.
• TR

  Tara Russell, MD

  All of the relevant financial relationships listed below have been mitigated.
  This individual has no financial relationships with ineligible companies.
• 

  Jonathan S. Abelson, MD MS (he/him/his)

  Staff Surgeon
  Lahey Hospital and Medical Center
  Tufts Medical Center
  Arlington, MA, United States

  All of the relevant financial relationships listed below have been mitigated.
  This individual has no financial relationships with ineligible companies.
• FF

  Fergal Fleming, MD MPH FRCSI FACS

  Associate Professor of Surgery and Oncology
  University of Rochester Medical Center
  University of Rochester Medical Center
  Rochester, NY, United States

  All of the relevant financial relationships listed below have been mitigated.
  This individual has no relevant relationships with ineligible companies.
• AM

  Amber Moyer, MD

  Assistant Professor of Surgery
  University of Colorado School of Medicine
  Denver, Colorado, United States

  Disclosure information not submitted.

Senior Author(s)

• 

  Jon D. Vogel, MD

  Professor
  University of Colorado School of Medicine
  University of Colorado
  Aurora, Colorado, United States

  All of the relevant financial relationships listed below have been mitigated.
  This individual has no financial relationships with ineligible companies.

Purpose/Background: Watch-and-Wait management (WW) is now routinely offered to patients with stage II or III rectal cancer who have had a complete clinical response (cCR) to total neoadjuvant therapy (TNT). WW protocols include serial magnetic resonance imaging (MRI) and sigmoidoscopy to surveil for local regrowth of cancer (local regrowth). When local regrowth is suspected, salvage surgical excision is typically performed. However, in some cases, salvage surgical pathology reveals the absence of local regrowth. The aim of this study was to evaluate the effectiveness of MRI or endoscopy alone to accurately detect local regrowth of rectal cancer during WW.

Methods/Interventions: We performed a multi-institutional retrospective review of patients with stage II or III rectal cancer who were diagnosed between 2016 and 2022, achieved cCR after receiving TNT, and were enrolled in a WW protocol. Surveillance endoscopy reports, MRI reports, salvage surgery procedure, and surgical pathology were assessed. Salvage surgery procedures were classified as total mesorectal excision (TME) or local excision (LE). We measured the rate of discordance between MRI and endoscopy for suspected local regrowth in this cohort. We then used the pathology results of salvage surgery to determine the sensitivity, specificity, and positive and negative predictive values of each diagnostic modality.

Results/Outcomes: The cohort included 307 patients from 13 institutions. Of these, 44 (18%) patients underwent salvage surgery at a median of 41 weeks (interquartile range 24-67 weeks) after the initiation of surveillance. Of these patients, 38 (86%) underwent TME and 6 (14%) had LE. Local regrowth was suspected by endoscopy or MRI in 39 (89%) and 15 (34%) patients who underwent salvage surgery, respectively. Discordance between endoscopy and MRI findings with regards to suspected regrowth was observed in 28 (64%) patients. The observed sensitivity of endoscopy for detecting local regrowth was 0.92±0.05 versus 0.42±0.07 for MRI (Tables 1-2). The specificity of endoscopy for detecting local regrowth was 0.25±0.15 versus 1.0±0 for MRI. The positive predictive value of endoscopy for local regrowth was 0.85±0.06 versus 1.0±0 for MRI. The negative predictive value of endoscopy for local regrowth was 0.40±0.22 versus 0.28±0.08 for MRI.

Conclusion/Discussion: In this study of locally advanced rectal cancer patients who underwent surveillance under a WW protocol, most patients with suspected local regrowth had discordant findings between MRI and endoscopy. Endoscopy was able to detect the vast majority of cases with local regrowth, but there were many false positives to consider. Alternatively, MRI did not detect the majority of cases with local regrowth, but there were no false positives with this test. These data indicate that endoscopy and MRI are complimentary in the detection of local regrowth during rectal cancer WW and provide support for their continued utilization.

Table 1
A compilation of the observed sensitivity, specificity, positive predictive value, and negative predictive value of endoscopy for detecting local regrowth of rectal cancer after TNT.
Table 2
A compilation of the observed sensitivity, specificity, positive predictive value, and negative predictive value of MRI for detecting local regrowth of rectal cancer after TNT.