Objective: The purpose of this study was to describe the clinicopathologic features of malignant transformation in patients with ovarian endometrioma, their treatment and outcome in the Kinki region, Japan.
Patients and methods: Patients meeting Sampson and Scott's criteria for cancer associated with endometriosis were identified by chart review and pathology reports. This retrospective survey describes 18 women with a history of ovarian endometrioma. These cases were followed as benign ovarian endometrioma before malignant transformation on the basis of imaging findings by gynecologic oncologists or radiologists.
Results: Mean age at presentation of malignant transformation was 45.2 years (range, 36-66 years), and 78% (n=14) were premenopausal women. The pattern of spread was local in 16 (89%), regional in 2 (11%) and distant in 0 (0%). There was a common left-sided predominance. Characteristic histologic findings were 61% clear cell carcinoma. Endometriosis-associated malignancies have a favorable prognosis. The patients showed long latency intervals before developing ovarian cancer (mean, 4.5 years; range, 1-16 years). Among them, subjects (n=10) whose ages are more than 45 years old had shorter latency intervals (mean, 1 year; range, 1-3 years), compared with those (n=8) aged less than 45 years old (mean, 8.4 years; range, 3-16 years).
Conclusion: Ovarian endometrioma could be viewed as a neoplastic process, particularly in perimenopausal women.