Increased MET Copy Number and its Differing Prognostic Values in Schistosomal and Non-Schistosomal Colorectal Cancers

Objective: To compare the prognostic role regarding gene copy number alteration of MET in schistosomal colorectal cancer (SCRC) and non-schistosomal colorectal cancer (NSCRC). Methods: : This retrospective study included 131 SCRC and 207 NSCRC patients, MET status was evaluated by fluorescent in situ hybridization (FISH) and immunohistochemistry (IHC) in tissue microarray sections. Results: : No significant differences were found in terms of clinical characteristics for SCRC patients and NSCRC patients except for age, where significantly more patients over 60 years old presented SCRC than NSCRC ( P < 0.001). 10.0% of cases were MET FISH-positive (mean ≥ 3 copies/cell). MET protein expression was positive in 60.3% of cases, but was not associated with MET FISH-positive ( P = 0.574). All patients were followed, and the median time was 51.3 months (range, 1.0 – 134.4 months). The prognostic significance of MET FISH-positive was different between SCRC and NSCRC. In SCRC, patients that were MET FISH-positive had significantly shorter survival compared to those that were MET FISH-negative ( P = 0.014). In NSCRC, the overall survival shows a slight trend toward favorable prognosis in association with MET FISH-positive for stage I-II patients ( P = 0.138), yet MET FISH-positive were significantly correlated to adverse survival for stage III-IV patients ( P = 0.015). Conclusions: : Increased MET copy number acts as a negative prognostic factor for SCRC, which has bidirectional prognostic significance in NSCRC.