Hatano S

Prediction of metastasis to mesorectal, internal iliac and obturator lymph nodes according to size criteria in patients with locally advanced lower rectal cancer

OBJECTIVE This study was performed to clarify whether size criteria could be applied to the prediction of metastasis to the mesorectal, internal iliac and obturator lymph nodes in patients with lower rectal cancer. METHODS A total of 915 lymph nodes (416 mesorectal, 199 internal iliac and 300 obturator) from 53 patients with lower rectal cancer who underwent a curative resection were examined; 83 lymph nodes were positive. The sizes of the lymph nodes immediately after removal and those of paraffin-embedded sections were compared for 175 lymph nodes. Then, size criteria for discriminating the status of metastasis were evaluated in 915 paraffin-embedded lymph nodes. RESULTS Regardless of the metastatic status and the site of the lymph nodes, a positive relationship was observed between the sizes of the lymph nodes immediately after removal and those of paraffin-embedded sections (P < 0.01). The area under the curve generated by a receiver-operating characteristics curve showed no significant differences between the short-axis diameter and the long-axis diameter, regardless of the lymph node location. Specifically, the optimal cutoff value of the short-axis diameter for discriminating the status of metastasis in mesorectal, internal iliac and obturator lymph nodes extrapolated to the living body was set at 6.2, 5.0 and 4.8 mm, with accuracies of 72.4, 63.8 and 59.3% and with positive predictive values of 29.9, 16.3 and 7.1%, respectively. CONCLUSIONS Size criteria were applicable for discriminating the metastatic status of lymph nodes from three different locations, although the positive predictive values of the size criteria for the internal iliac and obturator lymph nodes were lower than that for the mesorectal lymph nodes.

Identification of Risk Factors for Recurrence in High-Risk Stage II Colon Cancer

To identify risk factors for recurrence in patients with stage II colon cancer, Cox proportional hazards regression analysis was performed in 194 patients with stage II colon cancer who underwent curative surgery between April 1997 and December 2008. Thirteen clinical and pathologic factors, including use of fluoropyrimidine-based adjuvant chemotherapy in 113 of the patients (58.2%), were assessed. By multivariate analysis, only obstruction, perforation, and T4-level invasion were identified as independent risk factors affecting disease-free survival (DFS) (P < 0.01). The 5-year DFS rate was 70.6% in patients with one or more risk factors (n = 68) and 96.0% in patients with no risk factors (n = 126) (P < 0.01). These results suggest that obstruction, perforation, and T4-level invasion are suitable candidates for prediction of tumor recurrence in patients with stage II colon cancer. The oxaliplatin-based adjuvant chemotherapy, which has been reported to be effective in stage III colon cancer patients, may improve the prognosis in high-risk stage II colon cancer patients.

Prediction of Lateral Lymph Node Metastasis in Lower Rectal Cancer: Analysis of Paraffin-embedded Sections

OBJECTIVE In the surgical treatment for lower rectal cancer, preoperative selection of patients at high risk for lateral lymph node metastasis is important, since lateral lymph node dissection might impair genitourinary functions. We examined whether the status of lateral lymph node metastasis can be predicted from the lymph node size. METHODS The subjects were 533 (35 positive and 498 negative) lateral lymph nodes from 47 patients with lower rectal cancer who underwent curative resection with lateral lymph node dissection. The sizes of the lateral lymph nodes immediately after removal and those in paraffin-embedded sections were compared for 108 lateral lymph nodes from 13 patients. In addition, receiver-operating characteristic curves were generated for the 533 paraffin-embedded lateral lymph nodes from the 47 patients to determine the optimal cut-off size for discriminating between positive and negative lateral lymph nodes. RESULTS Irrespective of the presence/absence of metastasis and the long-/short-axis diameter, a positive relationship was noted between the sizes of the lateral lymph nodes measured immediately after removal and those measured on paraffin-embedded sections (P< 0.01). The area under the curve for the short-axis diameter differed little from that for the long-axis diameter (0.77 vs. 0.76, P =0.80). The optimal cut-off values of the short- and long-axis diameter extrapolated to the living body were 5.4 and 8.4 mm, respectively, with an accuracy of 72.8% for the short-axis diameter and 71.9% for the long-axis diameter. CONCLUSIONS Prediction of the status of lateral lymph node metastasis from the lymph node size (long-/short-axis diameter) may be a simple and reliable method. The optimal cut-off diameter should be validated in prospective imaging studies.