A new grading system " two-tier" in clasification of ovarian serous carcinoma and evaluation of P53 gene expression by immunohistochemical staining

Recently the use of “two tier«grading system in which ovarian serous carcinoma was classified as low-grade or high-grade in comparing to preceding system has improved authority in prognosis and survival. This approach is simplistic، reproducible، and based on biologic evidence. In this study، we reclassified ovarian serous carcinoma by a new two-tier system for grading and then evaluation of P53 expression in these tumors by immunohistochemistry method. We retrospectively reviewed 32 cases of ovarian serous carcinoma with previous diagnosis of well differentiated (eight cases) and moderate to poorly differentiated serous carcinoma (24 cases) and according»two tier«grading system in low-grade vs. high-grade serous carcinoma reclassified. Subsequntly all cases immunostained by P53 marker. Also clinical data related to survival of patients (with or without recurrence of tumor and death) and paraclinical findings such as presurgical blood serum level of CA125 are gathered. Out of total eight patients with previously diagnosis; well diferentiated serous carcinoma and of 24 patients with moderate to poorly differentiated serous carcinoma reclassified as low-grade and high-grade ovarian serous carcinoma respectively and a statistically significant difference was found between two groups. (P<0. 005) Also of total 24 cases with high grade serous carcinoma، in 12 cases (54%) P53 immunostaining was detected but in non of all low grade serous carcinoma was seen. All 8 low grade serous carcinoma were alive without recurrence of tumor. In 10 and 12 out of 24 cases with high grade serous carcinoma recurrence of tumor and death were seen respectively. Since the presence of P53 negative expression in all of low-grade serous carcinoma by immunostaining and low-grade serous carcinoma accounts for small pupulation of all ovarian serous carcinoma and also few cases in our study، we did not find significant differences between P53 expression and survival in two low-grade vs high-grade serous carcinoma groups.