Endometriosis-Associated Ovarian Carcinoma (EAOC)
December 1, 2001 3 minutes read
Endometriosis-Associated Ovarian Carcinoma (EAOC)
Abstract & Commentary
Synopsis: EAOC deviates from the non-EAOC in many of its key biological characteristics, including lower stage, different histologies, lower grade lesions, and improved survival.
Source: Erzen M, et al. Gynecol Oncol. 2001;83: 100-108.
Erzen and colleagues conducted a nested case-control study in which 58 patients with endometriosis-associated ovarian carcinoma (EAOC) were nested with 4 perfectly age-matched non-EAOC patients selected from among 425 women representing all FIGO stages of ovarian cancer without endometriosis. When compared in a case-control design with 4 perfectly age-matched non-EAOC patients nested to each EAOC case, the patients with EAOC proved to have lower stage disease (P = 0.000), show a completely different distribution of histologic subtypes (significant overexpression of endometrioid and clear cell carcinomas) (P = 0.0001), have predominantly lower grade lesions (P = 0.029), be devoid of any primary residual tumor (P = 0.0001), and most importantly, have demonstrated a significantly better overall survival (47/58 vs 126/232; OR, 2.89) (P = 0.0001). This better survival was evident in all age groups and for all histologic subtypes, but not explained by a better stage-specific survival in any FIGO stage. The 2 series also differed in their significant prognostic predictors in Kaplan-Meier and Cox analyses. In the EAOC group, the most significant predictors of overall survival in univariate analysis were age, histologic type, observation time for endometriosis, and distribution of endometriosis. In the non-EAOC group, such significant predictors were age, residual tumor, and type of therapy. In the multivariate Cox model, age and FIGO stage were the only 2 significant independent prognostic factors shared by these 2 series. In addition, histologic type and type of therapy proved to be significant independent predictors in the non-EAOC series. Erzen et al concluded that their data suggest that EAOC deviates from the non-EAOC in many of its key biological characteristics, but noted that confirmatory studies were necessary.
Comment by David M. Gershenson, MD
Endometriosis-associated cancer may assume several forms: 1) malignancy may arise in an extra-ovarian site of endometriosis; 2) malignancy may arise in an ovarian site of endometriosis; 3) malignancy may be associated with an ovarian site of endometriosis but not proven to arise in such; and 4) malignancy may arise in the ovary with extra-ovarian sites of endometriosis. This paper by Erzen et al addresses the second and third of these entities. Currently, the risk of malignancy developing in ovarian endometriosis is unknown, but it is thought to be in the range of only about 1%. The nested case-control design of this study is appealing, and the findings certainly underscore some important differences between endometriosis-associated ovarian cancer and ovarian cancer not associated with endometriosis. Clearly, EAOC patients have significantly lower stage disease, lower grade lesions, and less chance of residual tumor. Endometrioid and clear cell subtypes predominate in this group. They appear to have a significantly superior survival, which, on multivariate analyses, is principally related to age and lower stage disease. One of the interesting aspects of EAOC is recommended postoperative treatment. Because these entities are so uncommon, we do not have a standard postoperative therapy. Generally, these patients are treated with standard ovarian cancer therapy, ie, the combination of paclitaxel and carboplatin for 6-8 cycles. Our group tends to use pelvic irradiation or chemoradiation in this population a little more frequently than in non-EAOC, but there is no definite evidence that such a strategy is superior to chemotherapy alone.
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