54 Chapter 4 Abstract Purpose To analyze how the MRI reporting of rectal cancer has evolved (following guideline updates) in The Netherlands. Methods Retrospective analysis of 712 patients (2011-2018) from 8 teaching hospitals in The Netherlands with available original radiological staging reports that were re-evaluated by a dedicated MR-expert using updated guideline criteria. Original reports were classified as “free-text”, “semi-structured” or “template” and completeness of reporting was documented. Patients were categorized as low versus high-risk, first based on the original reports (high risk = cT3-4, cN+, and/or cMRF+) and then based on the expert re-evaluations (high risk = cT3cd-4, cN+, MRF+, and/or EMVI+). Evolutions over time were studied by splitting the study inclusion period in 3 equal time periods. Results A significant increase in template reporting was observed (from 1.6 to 17.6-29.6%; p<0.001), along with a significant increase in the reporting of cT-substage, number of N+ and extramesorectal nodes, MRF-invasion and tumor-MRF distance, EMVI, anal sphincter involvement, and tumor morphology and circumference. Expert re-evaluation changed the risk classification from high to low-risk in 18.0% of cases and from low to high-risk in 1.7% (total 19.7%). In the majority (17.9%) of these cases, the changed risk classification was likely (at least in part) related to use of updated guideline criteria, which mainly led to a reduction in high-risk cT-stage and nodal downstaging. Conclusion Updated concepts of risk stratification have increasingly been adopted, accompanied by an increase in template reporting and improved completeness of reporting. Use of updated guideline criteria resulted in considerable downstaging (of mainly high-risk cT-stage and nodal stage). Introduction MRI is routinely used to stratify rectal cancer patients for differentiated treatments based on the presence (or absence) of known high-risk features. Traditionally, the main high-risk features used in clinical guidelines to stratify patients for neoadjuvant treatment included cT3-4 disease, tumor invasion of the mesorectal fascia (MRF), and node-positive (cN+) disease (1-5). In this setup, borderline cT2-3 tumors posed a diagnostic challenge as
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