Preoperative Computerized Tomographic Assessment of Regional Lymph Node and Extramural Vascular Invasion in Colonic Cancer

Abstract

Objective: There have been recent attempts to transfer well-established principles of rectal cancer management to colonic cancer, thereby offering neoadjuvant chemotherapy to high-risk patients at least in the trial settings. Traditionally, postoperative chemotherapy is offered to patients with colonic tumors that metastasize into regional lymph nodes and have features of extramural vascular invasion (EMVI). If the same criteria are used for the selection of patients with colonic cancer for neoadjuvant chemotherapy, then their accurate preoperative detection becomes of paramount importance. The aim of the study was to establish the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the computerized tomographic (CT) assessment of lymph node involvement and EMVI in colonic cancer.

Materials and methods: This retrospective study included 53 consecutive adult patients (35 males and 18 females; median age, 72 years) who had complete preoperative CT staging of colonic cancer followed by its surgical resection during a 12-month period from January 1, 2012, to December 31, 2012. Patients with rectal and colonic tumors presenting as an emergency who did not have complete preoperative CT imaging were excluded. Preoperative CT findings on regional lymph node status and EMVI were compared with the final histopathological staging of resected specimens calculating sensitivity, specificity, PPV, and NPV of the test.

Results: In predicting regional lymph node metastases, CT scan had a sensitivity of 85% and a specificity of 24%. PPV was calculated as 63% and NPV as 50%. In predicting EMVI, it had a sensitivity of 69% and a specificity of 49%. PPV was 37% and NPV was 78%.

Conclusion: Preoperative CT scan does not allow an accurate detection of regional lymph node metastases and EMVI and has a tendency to overstage colonic cancer.

Keywords: Colonic cancer; computerized tomography; extramural vascular invasion; neoadjuvant treatment.

Figure 1.

CT scan (axial view) showing tumor of the hepatic flexure of the colon with features of EMVI (blue arrow)

Figure 2.

Coronal (a) and axial (b) CT post-contrast portovenous images of a stricturing hepatic flexure tumor with a prominent draining vessel [a key feature of extramural vascular invasion (red arrow), Axial CT portovenous phase images with nodal disease (green arrow) and hepatic flexure stricturing tumor (c)

Figure 3.

Axial CT portovenous phase with enlarged enhancing right retroperitoneal lymph node (green arrow) and a circumferential tumor of the descending colon (a), Axial CT in the portovenous phase (b) and coronal CT images (c) with dilated enhancing vessel and nodular outline features of extramural vascular invasion (red arrow)