PREOPERATIVE ESTIMATION OF NEURAL INVASION IN RECTAL-CARCINOMA

To reduce postoperative local recurrence in patients who undergo a ner ve preserving operation for rectal carcinoma, preoperative estimation of neural invasion would be desirable. For this purpose we clarified t he characteristics of rectal carcinomas with neural invasion and then evaluated the usefulness of matrix metalloproteinase 7 (MMP7) gene as an indicator for neural invasion. The study included 128 patients with primary rectal carcinoma. The histologic examination plus immunohisto chemical study for S-100 protein was performed. A reverse transcriptio n-polymerase chain reaction (RT-PCR) study for MMP7 using preoperative ly obtained biopsy specimens was also performed in 32 patients. Neural invasion was recognized in 38 (29.7%) of 128 tumors. The tumors with neural invasion were characterized by infiltrative growth pattern, fre quent lymphatic and venous permeation, frequent lymph node metastasis, and advanced stage of disease. The cases with neural invasion also sh owed a higher recurrent rate and worse prognosis. An RT-PCR study demo nstrated that a significantly higher expression of MMP7 mRNA was recog nized in neural invasion positive cases than in negative ones (p<0.05) , indicating that MMP7 may be a good indicator for neural invasion of rectal carcinoma. Neural invasion would be an additional useful factor for providing information on malignant potential. The RT-PCR results of MMP7 gene may be useful for predicting which tumors may develop neu ral invasion.