Objectives: Elevated serum levels of CA125 are observed not only in association with primary ovarian epithelial neoplasms but also in a variety of other clinical settings, including ovarian involvement by metastatic disease. There is considerable overlap in gross and histologic features between primary ovarian tumors and metastatic colorectal adenocarcinoma, which can make diagnosis particularly challenging in the setting of an increased CA125 level. The aims of this study were to determine how frequently serum CA125 is elevated in women with ovarian involvement by metastatic colorectal adenocarcinoma and to compare the features of cases with and without associated elevations of serum CA125.
Methods: Eighty-nine cases of histologically confirmed ovarian involvement by metastatic colorectal adenocarcinoma were identified by retrospective review. Clinicopathologic data were analyzed, including preoperative serum CA125 level (available in 42 cases). Features of cases with an associated increase in serum CA125 were compared with those of cases with no such elevation.
Results: Twenty-nine patients had an elevated serum CA125 level (>35 U/mL) preoperatively (range 39.0-556.3, median 143.0, mean 199.1). Thirteen patients had a serum CA125 level within the reference range, while forty-seven patients had no preoperative testing for serum CA125. Clinical, gross, and histologic features of cases with an associated increase in serum CA125 were generally similar to those of cases with a non-elevated serum CA125 concentration. In three cases, the tumor was initially diagnosed as an ovarian primary.
Conclusions: At least 32.6% of women with ovarian involvement by metastatic colorectal adenocarcinoma have an elevated serum CA125 level prior to oophorectomy. Such cases do not differ significantly from cases lacking such an association with respect to a variety of clinicopathologic features. The possibility of metastasis from a colorectal carcinoma merits consideration in the formation of the differential diagnosis for a woman with an adnexal mass and elevated serum CA125, even in the absence of an established history of gastrointestinal malignancy.