Evaluation of MRI for initial staging of esophageal cancer: the STIRMCO study

To compare the diagnostic accuracy of MRI and PET/CT combined versus standard staging methods (CT, endoscopic ultrasound [EUS], and PET/CT) for initial staging of esophageal cancer (EC). This study included patients newly diagnosed with histologically proven EC between 2017 and 2021. Patients underwent a 3-T esophageal MRI alongside standard staging (CT, EUS, PET/CT) prior to treatment. TNM-stages were assessed by two independent reviewers for MRI, CT, and PET/CT, with EUS evaluated by one operator. Discrepancies were resolved by a third reviewer. Patients were categorized based on treatment management: surgery (T1-T2N0M0), neoadjuvant (radio)chemotherapy (T3-T4a and/or N1-N2-N3M0), and palliative chemotherapy (T4b and/or M1). The reference standard was histopathology from surgical specimens or TNM staging from tumor board discussions. The area under the curve (AUC) was calculated for each imaging combination. 60 patients newly diagnosed with EC (50M/10F; mean age 66.5 years) were prospectively enrolled. MRI + PET/CT combination exhibited the highest AUC (0.92, 95% CI: 0.79-1) for differentiating curative versus palliative patients, without statistically significant difference compared to CT + EUS (0.80, 95% CI: 0.56-1, p = 0.34), CT + PET/CT (0.77, 95% CI: 0.53-1, p = 0.42), and CT + EUS + PET/CT (0.78, 95% CI: 0.58-0.97, p = 0.26). In term of differentiating patients eligible for upfront surgery from those with indication for neoadjuvant (radio)chemotherapy, the combination of CT + EUS + PET/CT demonstrated the highest AUC (0.90, 95% CI: 0.75-1) without statistically significant difference compared to CT + EUS (0.82, 95% CI: 0.56-1, p = 0.49), CT + PET/CT (0.79, 95% CI: 0.46-1, p = 0.36), and MRI + PET/CT (0.83, 95% CI: 0.65-1, p = 0.59). MRI + PET/CT combination is highly accurate for initial EC staging and non-inferior to standard methods, offering less invasiveness and reduced radiation exposure. Question Can MRI help improve the TNM staging of esophageal cancer? Findings MRI + PET/CT showed no statistically significant difference compared to endoscopic ultrasound (EUS) + CT + PET/CT in identifying curative vs palliative patients but with a tendency for improved staging. Clinical relevance Thoraco-abdominal MRI can provide added value (as a replacement of CT and EUS) in initial staging of esophagus cancer, particularly in cases of stenotic or advanced tumors.