Significance of MRI in rectal carcinoma therapy optimization – correlation of preoperative T- and N-staging with definitive histopathological findings

Abstract

In past decades, both prognosis and therapy of rectal cancer patients showed significant improvement. On the other hand, the incidence of rectal carcinoma continues to have a rising tendency. According to current UICC classification, patients in stage II rectal cancer or higher are indicated for neoadjuvant chemoradiotherapy (nCRT). Magnetic resonance imaging (MRI) is currently the most common diagnostic method used for preoperative staging of rectal cancer. Several studies already pointed out the inaccuracy of preoperative lymph node staging in patients with rectal cancer. The present study analyzed overall accuracy of MRI staging of rectal cancer and thus its accuracy in neoadjuvant therapy indication, by comparing preoperative MRI staging with definitive histopathologic results from resected tumors. This study evaluated cases of 92 patients with rectal tumor that underwent MRI examination followed by surgical resection. Tumors included in the analysis were ranging from T1 to T3b according to the TNM staging, with free circumferential resection margin (CRM), distance form mesorectal fascia more than 5 mm, negative intersphincteric plane and also negative extramural venous invasion (EMVI), while the N stage was not decisive. In all cases, both N-staging and T-staging were evaluated histologically and compared with preoperative MRI results. Significant difference in preoperative and postoperative N-staging was shown in 51 patients (61.45%). In majority of cases MRI lead to over-staging, which was observed in 44 cases (53.1 %), with complete negativity of lymph nodes proven by histological examination in 34 cases. On the other hand, under-staging of lymph nodes was observed only in 7 cases (7.4 %). The T-staging did not show significant differences. Results from this study confirm that MRI plays an important role in T-staging of rectal tumors, however, there are undoubtedly issues in N-staging of tumors, which should lead to reevaluation of neoadjuvant therapy indication in patients with positive lymph nodes according to MRI examination. Based on the results of this study, we see the future of preoperative staging of rectal tumors in precise T-staging together with accurate assessment of CRM and distance of tumor from mesorectal fascia as well as evaluation of intersphinteric plane and EMVI.

Prognostic significance of MR identified EMVI, tumour deposits, mesorectal nodes and pelvic side wall disease in locally advanced rectal cancer

“…Diagnostic criteria for significant lymph nodes and EMVI have evolved over time, and many mesorectal deposits can now be classified as TD and EMVI. Also, a recent study demonstrated that MRI overstaged lymph nodes in 53% of patients who underwent upfront surgery for stage II or less rectal cancer with 36% being totally LN negative at surgical histopathology [23]. We have demonstrated the effect of reclassification of mesorectal deposits into TD and LN on prognostication.…”

New trends in criteria indicative of neoadjuvant oncological therapy of lower and middle rectal cancers

“…This procedure is also based on the guidelines of the American Gastroenterology Society, which considers the rectum to reach only up to a distance of 12 cm from the anus (3,4,12). At the time of our study, patients were indicated for radiotherapy based on classifying the patients with positive lymph nodes as being in stage III of the disease, while the T stage of the disease is not taken into account (1,2,6). In our study, we relied on knowledge from the OCUM and MERCURY studies, as well as from other foreign studies (12)(13)(14)(15).…”

“…As a result of that, we can choose a more favorable strategy for the treatment of rectal tumors and thereby improve the prognosis of patients. Despite the improvement in the availability of diagnos-tic and therapeutic options, rectal cancer represents a major social problem, and the patient's prognosis depends on the stage of the disease at the time of diagnosis (1)(2)(3).…”

Low-Rank Matrix Denoising Algorithm-Based MRI Image Feature for Therapeutic Effect Evaluation of NCRT on Rectal Cancer

“…It was because that the pathological tissue fibrosis occurred after NCRT treatment. Expert research shows that the accuracy of each stage after treatment is T stage-50%, sensitivity-100%, specificity-35%, and N stage-65% and accuracy of circumferential margin-85% [20]. Subsequently, dynamic enhanced magnetic resonance technology was proposed, and studies suggested that MRIenhanced scanning can improve the accuracy of rectal cancer staging [21].…”