Baseline MR Staging of Rectal Cancer: A Practical Approach

Preoperative lateral lymph node features and impact on local recurrence after neoadjuvant chemoradiotherapy and total mesorectal excision for locally advanced rectal cancer: results from a multicentre international cohort study

AIM

Locally advanced rectal cancer (LARC) is commonly treated with neoadjuvant chemoradiotherapy (nCRT) and total mesorectal excision (TME) to reduce local recurrence (LR) and improve survival. However, LR, particularly associated with lateral lymph node (LLN) involvement, remains a concern. The aim of this study was to investigate preoperative factors associated with LLN involvement and their impact on LR rates in LARC patients undergoing nCRT and curative surgery.

METHOD

This multicentre retrospective study, including four academic high-volume institutions, involved 301 consecutive adult LARC patients treated with nCRT and curative surgery between January 2014 and December 2019 who did not undergo lateral lymph node dissection (LLND). Baseline and restaging pelvic MRIs were evaluated for suspicious LLNs based on institutional criteria. Patients were divided into two groups: cLLN+ (positive nodes) and cLLN- (no suspicious nodes). Primary outcome measures were LR and lateral local recurrence (LLR) rates at 3 years.

RESULTS

Among the cohort, 15.9% had suspicious LLNs on baseline MRI, and 9.3% had abnormal LLNs on restaging MRI. At 3 years, LR and LLR rates were 4.0% and 1.0%, respectively. Ten out of 12 (83.3%) patients with LR showed no suspicious LLNs at the baseline MRI. Abnormal LLNs on MRI were not independent risk factors for LR, distant recurrence or disease-free survival.

CONCLUSION

Abnormal LLNs on baseline and restaging MRI assessment did not impact LR and LLR rates in this cohort of patients with LARC submitted to nCRT and curative TME surgery.

Imaging of Oligometastatic Disease

Simple Summary

The imaging of oligometastatic disease (OMD) is challenging as it requires precise loco-regional staging and whole-body assessment. The combination of imaging modalities is often required. The more accurate imaging tool will be selected according to tumor type, the timing with regard to measurement and treatment, metastatic location, and the patient’s individual risk for metastasis. The most commonly used modalities are contrast-enhanced computed tomography (CT), magnetic resonance imaging and metabolic and receptor-specific imaging, particularly, ¹⁸F-fluorodesoxyglucose positron emission tomography/CT, used alone or in combination.

Abstract

Oligometastatic disease (OMD) is an emerging state of disease with limited metastatic tumor burden. It should be distinguished from polymetastatic disease due the potential curative therapeutic options of OMD. Imaging plays a pivotal role in the diagnosis and follow-up of patients with OMD. The imaging tools needed in the case of OMD will differ according to different parameters, which include primary tumor type, timing between measurement and treatment, potential metastatic location and the patient’s individual risk for metastasis. In this article, OMD is defined and the use of different imaging modalities in several oncologic situations are described in order to better understand OMD and its specific implication for radiologists.

MRI for Rectal Cancer: Staging, mrCRM, EMVI, Lymph Node Staging and Post-Treatment Response

Rectal cancer is a relatively common malignancy in the United States. Magnetic resonance imaging (MRI) of rectal cancer has evolved tremendously in recent years, and has become a key component of baseline staging and treatment planning. In addition to assessing the primary tumor and locoregional lymph nodes, rectal MRI can be used to help with risk stratification by identifying high-risk features such as extramural vascular invasion and can assess treatment response for patients receiving neoadjuvant therapy. As the practice of rectal MRI continues to expand further into academic centers and private practices, standard MRI protocols, and reporting are critical. In addition, it is imperative that the radiologists reading these cases work closely with surgeons, medical oncologists, radiation oncologists, and pathologists to ensure we are providing the best possible care to patients. This review aims to provide a broad overview of the role of MRI for rectal cancer.