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Session: ePoster: Rectal Cancer 12 (Sat315)

EP172 - Analysis of complication rate in rectal cancer patients with discrepant magnetic resonance imaging and pathologic staging

Saturday, May 10, 2025
3:25 PM – 3:30 PM PT
Location: Monitor 10, Sails Pavilion, Upper Level

    ePoster Presenter(s)

  • Susan Muncner, MD

    General Surgery Resident PGY3
    University of Alberta
    Edmonton, AB, Canada

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

    • Author(s)

  • JD

    Jaspreet Dosanjh, RN MN

    Registered Nurse
    University of Alberta
    Edmonton, Alberta, Canada

    Disclosure information not submitted.

  • Andrea Lin, MD

    General Surgery Resident PGY-4
    University of Alberta
    University of Alberta
    Edmonton, Alberta, Canada

    Disclosure information not submitted.

  • CN

    Carmen Ng, MSc

    Medical Student Year4
    University of Alberta
    Edmonton, Alberta, Canada

    Disclosure information not submitted.

  • MD

    Mark Dykstra, MD MSc FRCSC

    Assistant Professor
    University of Alberta
    Edmonton, Alberta, Canada

    Disclosure information not submitted.

  • RS

    Ryan Snelgrove, MD FRCSC

    Assistant Professor
    University of Alberta
    Edmonton, Alberta, Canada

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

  • JJ

    Jacob L. Jaremko, MD PhD FRCPC

    Professor - Department of Radiology and Diagnostic Imaging
    University of Alberta
    Edmonton, Alberta, Canada

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

    • Senior Author(s)

  • HW

    Haili Wang, MD MSc FRCSC

    Associate Professor
    University of Alberta
    Edmonton, Alberta, Canada

    Disclosure information not submitted.

All of the relevant financial relationships listed below have been mitigated.
Susan Muncner, MD: This individual has no financial relationships with ineligible companies.
Ryan Snelgrove, MD FRCSC: This individual has no financial relationships with ineligible companies.
Jacob L. Jaremko, MD PhD FRCPC: This individual has no financial relationships with ineligible companies.
Image or Table (Do Not add text here):

Purpose/Background: Clinical staging of rectal cancer (RC) relies on magnetic resonance imaging (MRI), which in turn determines treatment pathway. With initial understaging, unexpected adjuvant treatment (AT) is typically needed, which creates risk for associated toxicity. Initial overstaging results in unnecessary neoadjuvant therapy (NAT) in the form of high-dose radiation, with risks of anastomotic strictures, damage to healthy tissue and anorectal dysfunction. Anecdotally, we have experienced both outcomes at our centre, and discrepant RC MRI staging vs. pathology is described in the literature. However, there is a paucity of data regarding the clinical impact of discrepant staging on patient outcomes. Thus, the objective of this study was to investigate complication rates in RC patients with discrepant staging.

Methods/Interventions: This was a retrospective cohort study using an established colorectal database at a single tertiary centre. Patients with a pre-operative diagnosis of RC who underwent NAT short-course radiation or went straight to surgery from November 2018 - 2023 were selected. This subset of RC patients was chosen to remove the potential confounding of NAT downstaging tumours, creating an artificial discrepancy between the initial MRI and final pathology. Demographic data, pre-operative MRI staging, pathologic results, NAT/AT details, and post-operative complications up to one-year post-operatively were collected. Differences in proportion were compared using Fisher’s exact test.

Results/Outcomes: The study sample included 69 patients (mean[SD] age 65.4[10.9] years, 27 females (39.1%), BMI 28.8[5.71]) across all five years. Of these, 65% (n=45) went straight for surgery. When comparing MRI vs pathologic staging, there was a 14.3% discrepancy in T-stage (n=10), 21.4% in N-stage (n=15), and 18.6% in both (n=13). In total, only 45.7% had correct MRI staging. Patients were then stratified according to AJCC stage discrepancy. Approximately 36% (n=25) received incorrect treatment based on preoperative staging; 16 patients went straight for surgery when NAT should have been recommended, and 9 patients received unnecessary radiation. One of these 9 patients developed radiation proctitis within one year. Other complications included conditions such as AT toxicity, pulmonary embolism, and presacral abscesses. We showed trends towards higher complication rates during index stay, 30 day readmissions, 1 year overall complications, and 1 year adjuvant toxicities in those with wrong staging, however, these were not significantly different at this sample size.

Conclusion/Discussion: In this single centre study, 36% of RC patients received incorrect treatment due to preoperative staging. Complication rates related to AT were high, highlighting the importance of accurate staging to determine correct treatment decisions. We showed trends towards increased complications in patients with the wrong staging during index stay, 30 day readmissions, 1 year overall complications, and 1 year adjuvant toxicity. Long term followup is likely to reveal further adverse events related to incorrect staging. Given that over 45% of patients of this relatively small study had an incorrect MRI stage and over 1/3 were thus incorrectly treated, we expect increasing statistical significance when larger sample sizes are considered. We hope to use this data to decrease complication rates by reducing unnecessary treatments in RC.