Comparison of mutations of Ki-RAS and p53 immunoreactivity in borderline and malignant epithelial ovarian tumors

Ovarian tumors of low malignant potential ("borderline tumors") have been p roposed variably to represent a distinctive type of malignancy, precursors of frank ovarian malignancy, or a nonmalignant process. We analyzed 81 mali gnant and 39 borderline ovarian tumors for p53 immunoreactivity and alterat ions in codon 12 of Ki-RAS in order to correlate these alterations with tum or and cell type. Diffuse p53 immunoreactivity was significantly more preva lent among malignant (36 of 81, 44%) than among borderline (3 of 39, 8%) tu mors and was particularly prevalent among serous invasive carcinomas (16 of 26, 62%). Conversely, mutations in codon 12 of Ki-RAS were significantly m ore prevalent in borderline (16 of 39, 41%) than in malignant (9 of 81, 11% ) ovarian tumors and were most prevalent among mucinous tumors. This prelim inary molecular analysis suggests that serous borderline tumors have some m olecular features usually associated with malignancy but are unlikely to re present a precursor of invasive serous carcinoma. In contrast, mucinous bor derline tumors may represent a precursor or variant of mucinous carcinoma o f the ovary.