Abstract
BackgroundPreoperative identification of rectal cancer lymph node status is crucial for patient prognosis and treatment decisions. Rectal magnetic resonance imaging (MRI) plays an essential role in the preoperative staging of rectal cancer, but its ability to predict lymph node metastasis (LNM) is insufficient. This study explored the value of histogram features of primary lesions on multi-parametric MRI for predicting LNM of stage T3 rectal carcinoma.MethodsWe retrospectively analyzed 175 patients with stage T3 rectal cancer who underwent preoperative MRI, including diffusion-weighted imaging (DWI) before surgery. 62 patients were included in the LNM group, and 113 patients were included in the non-LNM group. Texture features were calculated from histograms derived from T2 weighted imaging (T2WI), DWI, ADC, and T2 maps. Stepwise logistic regression analysis was used to screen independent predictors of LNM from clinical features, imaging features, and histogram features. Predictive performance was evaluated by receiver operating characteristic (ROC) curve analysis. Finally, a nomogram was established for predicting the risk of LNM.ResultsThe clinical, imaging and histogram features were analyzed by stepwise logistic regression. Preoperative carbohydrate antigen 199 level (p = 0.009), MRN stage (p < 0.001), T2WIKurtosis (p = 0.010), DWIMode (p = 0.038), DWICV (p = 0.038), and T2-mapP5 (p = 0.007) were independent predictors of LNM. These factors were combined to form the best predictive model. The model reached an area under the ROC curve (AUC) of 0.860, with a sensitivity of 72.8% and a specificity of 85.5%.ConclusionThe histogram features on multi-parametric MRI of the primary tumor in rectal cancer were related to LN status, which is helpful for improving the ability to predict LNM of stage T3 rectal cancer.
Highlights
Preoperative identification of rectal cancer lymph node status is crucial for patient prognosis and treatment decisions
The 2020 NCCN guidelines recommend that the choice of treatment for stage T3 rectal cancer should refer to N stage, and preoperative neoadjuvant chemoradiotherapy (nCRT) should be performed according to the presence or absence of lymph node metastasis (LNM) [16]
The diagnostic accuracy of T staging of rectal cancer has reached 88–99% [20], the on-going LNM evaluation accuracy is still less than 80% [21]. 25% of lymph nodes are likely to be over-staged, which will lead to unnecessary preoperative overtreatment, and the possible short-term and long-term complications will aggravate the damage caused by the tumor in these patients [22]
Summary
Preoperative identification of rectal cancer lymph node status is crucial for patient prognosis and treatment decisions. Rectal magnetic resonance imaging (MRI) plays an essential role in the preoperative staging of rectal cancer, but its ability to predict lymph node metastasis (LNM) is insufficient. The treatment of locally advanced rectal cancer includes neoadjuvant chemoradiotherapy (nCRT) and total mesorectal excision (TME). LNM is an important prognostic factor for local recurrence and distant metastasis [1]. The European Society for Medical Oncology (ESMO) guidelines recommend that low-risk T3N0 patients do not need preoperative nCRT and only need TME. For most patients with T3N1-2 cancer, preoperative nCRT is. The preoperative identification of lymph node status in patients with T3 rectal cancer plays an important role in guiding treatment decision-making. The accuracy of using MRI morphological criteria such as diameter, shape, boundary, and signal heterogeneity to assess the status of lymph nodes is unsatisfactory [3,4,5]
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