February's paper of the month looks at the Prognostic significance of MR identified EMVI, tumour deposits, mesorectal nodes and pelvic side wall disease in locally advanced rectal cancer
Anuradha Chandramohan, Rohin Mittal, Romina Dsouza, Harish Yezzaji, Anu Eapen, Betty Simon, Reetu John, Ashish Singh, Thomas S. Ram, Mark R. Jesudason, Dipti Masih, Reka Karuppusami.
Colorectal Disease, 00:1–11, December 2021
What is known about the subject?
Locally advanced rectal cancer requires complex treatment including, in the majority of cases, neoadjuvant chemoradiotherapy and radical surgery following total mesorectal excision (TME) principles. MRI plays a crucial role in deciding the need for neoadjuvant therapy, based mainly on the clinical TNM stage and prediction of circumferential resection margin (CRM) status. Recently, evidence has emerged for prognostic significance of some features not included in TNM classification: presence of extramural tumor deposits (TD), extramural vascular invasion (EMVI) and involvement of the pelvic sidewall (PSW). These features should be predictable on MRI. On the other hand, the prognostic significance of MRI-detected lymph node metastases (mr-LNM) remain unclear.
What the study adds?
This study aimed to assess the prevalence, prognostic significance, cumulative effect of one or more of these features, and to calculate the inter-and intra-reader reliability of mr-EMVI, mr-TD, mr-LNM and mr-PSW disease in staging and restaging MRI of patients with locally advanced rectal cancer. The authors analyzed data from patients with stage IIA–IIIC rectal adenocarcinoma treated with neoadjuvant long course chemoradiotherapy (LCCRT) and total mesorectal excision (TME) surgery.
The study showed a high prevalence of EMVI, TD and PSW on staging MRI. The presence of EMVI and TD on staging and restaging MRI adversely affected disease-free (DFS) and overall survival (OS). In addition, PSW disease on staging and restaging MRI, and poor response (MR-TRG 4 and 5) adversely affected OS. Results of the study showed that neither T stage nor CRM on staging MRI had prognostic significance. There was a strong association between advanced T stage and positive CRM with mr-TD and mr-EMVI. While the presence of TD significantly affected prognosis, this was not true for LNM.
Implications for colorectal practice
Apart from the traditionally used TNM stage and CRM, there are other prognostic features for rectal cancer. MRI diagnosed EMVI, TD and PSW disease are important poor prognostic markers. Thus, classification of mesorectal disease into EMVI, TD and LN could affect decision making and prognostication, leading to potential further benefit from therapies such as total neoadjuvant chemotherapy in patients with EMVI and TD and reduced use of neoadjuvant therapy based on N-stage. Persistence of these findings after LCCRT leads to poor outcome.
The study demonstrated worse prognosis and a cumulative effect of MRI identified EMVI, TD and PSW disease. Patients with these findings may thus need more aggressive neoadjuvant therapy and persistence of adverse prognostic factors should warn the surgeon of possible worse outcomes and potential change in planned treatment/surveillance.