Kazuhisa Yoshimoto

Importance of Thymidine Phosphorylase Expression at the Invasive Front of T3 Rectal Cancer as a Prognostic Factor

Purpose: Vascular endothelial growth factor (VEGF) and thymidine phosphorylase (TP) are angiogenic factors. We evaluated the relationship between the degree of expression of binary angiogenic factors and the malignant potential of colorectal cancer. Methods: This study was conducted in 61 patients with T3 rectal cancer who underwent surgical curative resection between 1998 and 2002. Paraffin-embedded sections of their surgical specimens were immunostained for VEGF and TP. The relationship between the expression level of binary angiogenic factors and lymph node metastasis was evaluated. Results: Expression of VEGF was present only in the tumor cells of all patients, and expression was absent in the stromal cells around the invasive front of the tumor. Expression of TP was mainly present in the stromal cells around the cancer nests or around the invasive margin of the cancer. There was no relationship between expression of TP in the stromal cells around the invasive front of the tumor and lymph node metastasis. However, there was a significant relationship between expression of TP at the invasive front of the tumor and lymph node metastasis (p = 0.014). Moreover, TP expression in the tumor cells was the only independent factor that correlated with the postoperative recurrence (p = 0.024) with an odds ratio of 11.973 by multivariate logistic regression analysis. Conclusion: Expression of TP at the invasive front of the tumor may be a useful indicator of the malignant potential of advanced rectal cancer.

Early cystoadenocarcinoma of vermiform appendix simulating submucosal tumor of the cecum

Colonoscopy was performed on a 54-year-old man with occult melena in our hospital. A submucosal tumor with a maximum diameter of 5cm was detected in the cecum. The tissue of the submucosal tumor was not obtained by endoscopic biopsy, and tumor diagnosis could not be confirmed by this method. A large, hypodense, cystic structure extending below the inferior wall of the cecum was revealed by computed tomography (CT). Because the tumor was too large to be a benign tumor, we were able to conclude it was malignant. After receiving informed consent from the patient, laparoscopic right colectomy was performed for both diagnosis and treatment in June 2004. As the swollen vermiform appendix pressed the cecum extraluminally, endoscopic examination indicated the possibility of submucosal tumor. Postoperative pathological diagnosis was cystoadenocarcinoma, the tumor was extended within the mucosal layer, and no lymph node metastasis was detected. Cancer cells were not present in the viscous liquid of the vermiform appendix intracavitary, either. The patient left the hospital in 10 days postoperatively. He regularly underwent examinations including CT, and no recurrence was detected for more than 24 months following the laparoscopic operation.