RESUMO
Background: Gastric and colorectal cancers are the second and the fourth most common cancers in Iran, respectively. The presence of Murine Double Minute 2 (MDM2) has been identified in many cancers and its relationship with prognosis is under investigation. This study aimed to assess the status of MDM2 and its relationship with prognostic factors in gastric and colorectal carcinoma. Materials and Methods: This study was performed on 99 paraffin blocks of gastric and colorectal cancers, during the years 2001 to 2007 from Mostafa Khomeini Hospital, Tehran, Iran. Tissue sections were prepared, stained with Hematoxylin and Eosin and immunohistochemistry to evaluate for MDM2 expression. The type of tumor, lymph node involvement and tumor grade was determined. Results: Of the 99 cases, 34.3% and 65.7% cases were diagnosed with gastric and colorectal adenocarcinoma, respectively. The average tumor size was 5.5 cm. MDM2 expression level was 82.4% and 90.8% in gastric and colorectal adenocarcinoma, respectively. No statistical difference was found between MDM2 expression and various prognostic factors; however, significant correlation was observed between gastric (P = 0.03) and colorectal (P = 0.03) tumor size and the percentage of MDM2 immunoreactivity. Conclusion: Considering the role of MDM2 in cell growth and its positive correlation with tumor size (an established prognostic factor), it can be indirectly concluded that MDM2 is also important in prognosis. However, additional investigation is needed.