MRI cT1–2 rectal cancer staging accuracy: a population-based study

Abstract

Background Adequate MRI‐based staging of early rectal cancers is essential for decision‐making in an era of organ‐conserving treatment approaches. The aim of this population‐based study was to determine the accuracy of routine daily MRI staging of early rectal cancer, whether or not combined with endorectal ultrasonography (ERUS). Methods Patients with cT1–2 rectal cancer who underwent local excision or total mesorectal excision (TME) without downsizing (chemo)radiotherapy between 1 January 2011 and 31 December 2018 were selected from the Dutch ColoRectal Audit. The accuracy of imaging was expressed as sensitivity, specificity, and positive predictive value (PPV) and negative predictive value. Results Of 7382 registered patients with cT1–2 rectal cancer, 5539 were included (5288 MRI alone, 251 MRI and ERUS; 1059 cT1 and 4480 cT2). Among patients with pT1 tumours, 54·7 per cent (792 of 1448) were overstaged by MRI alone, and 31·0 per cent (36 of 116) by MRI and ERUS. Understaging of pT2 disease occurred in 8·2 per cent (197 of 2388) and 27·9 per cent (31 of 111) respectively. MRI alone overstaged pN0 in 17·3 per cent (570 of 3303) and the PPV for assignment of cN0 category was 76·3 per cent (2733 of 3583). Of 834 patients with pT1 N0 disease, potentially suitable for local excision, tumours in 253 patients (30·3 per cent) were staged correctly as cT1 N0, whereas 484 (58·0 per cent) and 97 (11·6 per cent) were overstaged as cT2 N0 and cT1–2 N1 respectively. Conclusion This Dutch population‐based analysis of patients who underwent local excision or TME surgery for cT1–2 rectal cancer based on preoperative MRI staging revealed substantial overstaging, indicating the weaknesses of MRI and missed opportunities for organ preservation strategies.

Local recurrence after local excision of early rectal cancer: a meta-analysis of completion TME, adjuvant (chemo)radiation, or no additional treatment

“…This implies that neoadjuvant chemoradiotherapy led to overtreatment of patients with non‐responding or partially responding tumours, and likely resulted in increased morbidity. More importantly, as clinical staging by imaging has been shown to lack accuracy, this treatment strategy also incorporates patients with low‐risk tumours, who could have been treated with local excision only 7,8 . For this reason, a strategy comprising local excision of small lesions without signs of risk factors on preoperative imaging seems more attractive.…”

“…Clinical staging by endoscopy, MRI and endoscopic ultrasonography (EUS) has low accuracy in distinguishing low‐risk T1 from high‐risk T1 or early T2 rectal cancers 7,8 . Therefore, local excision as an initial diagnostic procedure is an attractive approach in early rectal cancer.…”

Can Ultrasound Elastography Discriminate between Rectal Adenoma and Cancer? A Systematic Review

“…MRI is the first choice for radiological staging of a primary rectal tumor. The modality yields a high accuracy in advanced tumors (T3-T4) [6], but is reported to overstage early rectal malignancies [8], thus potentially resulting in missed opportunity for organ preservation treatment, e.g., transanal endoscopic microsurgery (TEM) or the watchful waiting strategy (WW). ERUS is considered superior to MRI in the staging of T1 and T2 rectal malignancies, and, consequently, the international guidelines recommend supplemental ERUS when evaluating advanced adenomas or early rectal malignancies [9].…”

Radiomics and Magnetic Resonance Imaging of Rectal Cancer: From Engineering to Clinical Practice

“…As to N-staging, MRI has been shown to have limited performance, yielding a sensitivity and specificity of approximately 70 to 80% with pathology as the gold standard [ 15 , 16 ]. Detering et al [ 17 ] have recently investigated the performance of MRI in the T and N staging of early RC, showing poor accuracy in T staging (54%), with 31% and 15% of patients being clinically overstaged and understaged, respectively. Overstaging was slightly reduced (from 54.7 to 31%) with combined MRI and endorectal ultrasonography, highlighting the overall limited performance of MRI and endorectal ultrasonography in cT1 staging.…”