K-RAS POINT MUTATION DETECTION BY PCR/RFLP ANALYSIS VERSUS HISTOPATHOLOGY IN HAMSTER EXPERIMENTAL PANCREATIC CANCER MODEL—WHICH SENSITIVITY IS HIGHER IN DETECTION OF METASTASES?

Abstract

We have previously established a curative resection model in hamster experimental pancreatic cancer. Pathological examination should be enriched by sensitive methods to detect residual disease. Thus, a method of early diagnosis would be helpful for better follow-up. K-ras mutation has a relationship > 80% with pancreatic cancer. The purpose of this study was to clarify whether the sensitivity of histopathological (H) and molecular level (ML) differs in the diagnosis of metastatic sites. HaP-T1, a cell line derived from BHP induced pancreatic cancer was used in these experiments. A tissue derived from subcutaneously implanted cancer cells was implanted orthotopically. Partial pancreatectomy and splenectomy were done. Hamsters were divided in 3 groups: 1. Positive control (n=33), 2. Surgery performed at Day 7 (n=30), and 3. Surgery performed at Day 14 (n=27). Three animals of each group were sacrificed every 7 days until Day 77 and necropsy was performed. Surgically-resected and necropsied specimens were sent for histopathology and for detection of K-ras point mutation by PCR/RFLP analysis. Positive controls showed metastases in the H starting from Day 35 in 13 cases (39.4%) and in the ML starting from Day 21 in 22 cases (66.6%). Groups 2 and 3 showed free margins in the surgically-resected specimens. In Group 2, tumoral recurrence was detected from Day 42 in one case (3.3%) in the H and in 2 cases (6.6%) in the ML. In Group 3, metastases were detected from Day 35 in one animal (3.3%) in the H and ML in 2 cases (6.6%). PCR/RFLP analysis sensitivity rate was higher when compared with histopathological findings. These experiments showed the importance of possible use of this method for better staging and follow up of pancreatic cancer.