| Part I The study on tumor infiltration in mesorectum of rectal cancer by spiral computed tomography and histopathologyObjective To evaluate the accuracy of spiral computed tomography for preoperative T staging , circumferential resection margin(CRM) status and the degree of tumor infiltration in mesorectum of rectal cancer by contrast with large slice pathologic technique .Methods Fifty-seven patients with rectal cancer underwent preoperative spiral computed tomography. Images were obtained in the arterial, portal venous and balanced phases. Two radiologists independently evaluated the depth of tumor invasion into the rectal wall (T staging), circumferential resection margin (CRM) status, the degree of tumor infiltration in mesorectum on transverse CT images. The patients underwent total mesorectal excision (TME) by the same experienced colorectal surgeon within four days. Large slice technique was used in the pathologic study to ascertain the T staging, circumferential resection margin status and the degree of tumor infiltration in mesorectum. The spiral computed tomography findings were compared with pathologic results. Accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were assessed, respectively.Results All the 57 tumors were well displayed on the spiral computed tomography. The mesorectum of 54 patients (94.7%) was identified clearly on the CT images. The overall spiral computed tomography accuracy was 91.2% (52/57) for T staging and 93.0%, 91.2% and 98.2% for T1, T2, T3 staging, respectively. The overall spiral computed tomography accuracy was 93.0% (53/57) for the degree of tumor infiltration in mesorectum and 94.7%, 94.7% and 96.5% for degree I , II, III. Fifty-three cases (93.0%) were accurately predicated with the circumferential resection margin status. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) was 80.0%, 97.6%, 92.3% and 93.2%, respectively. The spiral computed tomography measurements of T staging, the degree of tumor infiltration in mesorectum and circumferential resection margin status were corresponded with the histopathological diagnosis. (К=0.83, P <0.01;К=0.89,P <0.01;К=0.76, P <0.05).Conclusion Spiral computed tomography enables accurate preoperative assessment for T staging, the degree of tumor infiltration in mesorectum and circumferential resection margin (CRM) status of rectal cancer. Spiral computed tomography can assess the tumor infiltration in mesorectum preoperatively, and provide valuable information for planning reasonable mesurements for the different patients. Part II Prognostic analysis of tumor infiltration in mesorectum for patients with rectal cancerObjective To study the relationship between tumor infiltration in mesorectum and prognosis of the patients with rectal cancer. To identify the correlations between tumor infiltration in mesorectum and clinicopathologic characteristics.Methods Specimens from 49 patients with rectal cancer underwent total mesorectal excision in our hospital were studied by the large slice pathologic technique. The local recurrence rate, metastasis rate and five-years survival rate were investigated, respectively.Results The rate of circumferential resection margin involvement was 24.5%(12/49). Local recurrence rate was 12.2% (6/49), the distant recurrence rate was 26.5% (13/49), and the five-years survival rate was 67.3% (33/49). In the 12 patients with positive circumferential resection margin, the local recurrence rate was 33.3%, whereas 5.4% in those with negative circumferential resection margin (x~2=6.577, P = 0.010). Distant recurrence was 50% in patients with positive circumferential resection margin, whereas 18.9% in those with negative one (x~2=4.491, P = 0.034). Kaplan- Meier survival analysis showed survival time was correlative with the circumferential resection margin status (log-rank, P=0.009). Five-years survival rate was 33.3% in the patients with positive circumferential resection margin, compared with that 78.4% in those with negative one. The local recurrence rate of the three different degree of tumor infiltration in mesorectum (I,II,III) were 0%, 7.7% and 31.3% (x~2=7.357, P =0.015), and the metastasis rate were 10%, 23.1% and 50% (x~2=7.405, P =0.025), respectively. The different degree of tumor infiltration in mesorectum developed different five-years survival rate ( I : 90%, II: 69.2%, III: 37.5% ). Kaplan-Meier survival analysis showed survival time was correlative with the degree of tumor infiltration in mesorectum (log-rank, P= 0.012). Tumor diameter, T staging , N staging, the distance away from the anocutaneous line , tumor localization and operation type were proved to be independent factors influencing the circumferential resection margin status of rectal cancer (x~2=4.451, P=0.035; x~2=20.283, P=0.000; x~2=7.773, P = 0.018; x~2=6.502, P = 0.040; x~2=4.421, P=0.035; x~2=5.754, P = 0.016 ) . Tumor diameter, T and N staging were factors influencing the degree of tumor infiltration in mesorectum(x~2=6.849, P=0.033; x~2=34.845, P=0.000;x~2=17.266,P = 0.002) .Conclusion The circumferential resection margin and the degree of tumor infiltration in mesorectum were the important predictors of local and distant recurrence as well as survival of patients with rectal arcinoma. The circumferential resection margin status of the rectal cancer has significant correlation with tumor diameter, T staging, N staging, the distance away from the anocutaneous line, tumor localization and operation type. Tumor diameter, T and N staging were the factors correlated with the degree of tumor infiltration in mesorectum. |
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