Malignant Transformation Arising from Mature Cystic Teratoma of the Ovary: a Retrospective Study of 20 Cases

Objectives: Mature cystic teratoma (MCT) of the ovary rarely undergoes malignant transformation (MT). Malignant transformation carries a significantly worse prognosis than epithelial ovarian cancer, regardless of whether postoperative chemotherapy or radiotherapy is applied. The rarity of this tumor has posed a significant challenge to developing standardized postoperative management protocols. The aim of this study was to review our experience with MT and to describe our current treatment practices.

Methods: A retrospective chart review of these patients was performed that identified 20 women treated for MT of MCT at our centers between 1988 and 2008.

Results: The median age was 52.5 (range, 29-77) years. Fifteen patients had squamous cell carcinoma (SCC), and 5 patients had other histological subtypes. The International Federation of Gynecology and Obstetrics stage distribution was as follows: 11 were stage I, 4 were stage II, 4 were stage III, and 1 was stage IV. All patients underwent an initial laparotomy. Eleven patients received adjuvant treatment: 8 were treated with chemotherapy, 2 with concurrent chemoradiation therapy, and 1 with radiation therapy. Platinum-based chemotherapy was the first-line regimen. The overall 1-year survival rate was 70%. Significant correlations between overall survival and age, stage, and residual tumor were presented (P = 0.044, P = 0.0107, P < 0.0001, respectively). Eight patients with advanced stage died of their disease. Four patients, however, were treated with adjuvant chemotherapy or concurrent chemoradiation therapy and survived more than 1 year. One stage III patient had a disease-free interval of 2 years. Two cases of SCC treated with combination platinum/taxane chemotherapy temporarily responded. In the other 2 cases of SCC, concurrent chemoradiation therapy with nedaplatin also resulted in tumor regression.

Conclusions: The prognosis of MT is highly dependent on age, stage, and optimal cytoreduction. Adjuvant treatment has not been standardized, although our experience supports the use of combination platinum/taxane chemotherapy.