Differentiating primary from metastatic ovarian tumors of gastrointestinal origin by CT.

Purpose: To determine differentiating CT imaging features of primary ovarian cancers from ovarian metastases of gastrointestinal origin.

Methods: Retrospective study of 50 patients with new ovarian lesions on CT, half were primary ovarian cancers and half gastrointestinal metastases. Two blinded independent readers described tumor characteristics on CT (size, laterality, margin, etc.) and ancillary features (ascites, peritoneal seeding, lymphadenopathy, etc.). Patient age, sex, cancer history, and tumor marker levels for CA-125 and CEA were collected. Wilcoxon test and Pearson's chi-squared test were used for statistical analysis.

Results: 50 patients with mean age of 62.1 years were included. Ovarian metastases were more likely to be cystic/mainly cystic (p=0.013), have smooth margins (p=0.011), and have no/mild enhancement (p<0.001). Primary ovarian lesions were associated with moderate to large volume of ascites (p=0.047) and more commonly seen with lymphadenopathy (p=0.008). Laterality was not significantly different between the two groups. CA-125 level was more commonly elevated in primary ovarian lesions (87% vs 50%, p=0.018), and with much higher values (1076.5 vs 155.1, p=0.013). CEA level was more commonly elevated in metastatic ovarian lesions (83.3% vs 15.4%, p<0.001), and with higher values (72.4 vs 2.1, p<0.001).

Conclusion: Ovarian metastases were more frequently smooth-margined and cystic with little enhancement. Primary ovarian lesions were more commonly associated with lymphadenopathy and larger volume of ascites. Tumor markers CEA and CA-125 were more frequently elevated in metastatic and primary lesions, respectively. Cancer history was the only variable that increased the odds of metastasis and therefore it is important to always correlate with history of cancer.