Malignant transformation of ovarian mature cystic teratoma into squamous cell carcinoma: a Taiwanese Gynecologic Oncology Group (TGOG) study

OBJECTIVE: The malignant transformation (MT) of ovarian mature cystic teratoma (MCT) to squamous cell carcinoma (SCC) is very rare. This study analyzed cases from multiple medical centers in Taiwan to investigate the clinicopathologic characteristics, treatment, and prognostic factors of this disease and reviewed related literature. METHODS: Pathological reports of 16,001 patients with primary ovarian cancer who were treated at Taiwan medical centers from 1990 to 2011 were reviewed. In total, 52 patients with MT of MCT to SCC were identified. RESULTS: Among all ovarian MCTs, the incidence of MT to SCC is 0.2%. The median age of patients was 52 years (range, 29–89 years), and the mean tumor size was 10.5 cm (range, 1–40 cm). We analyzed the patients in our study and those in the literature and determined that early identification and complete surgical resection of the tumor are essential for long-term survival. In addition, adjuvant chemotherapy or concurrent chemoradiotherapy can be used to treat this malignancy. Old age, large tumor size (≥15.0 cm), and solid components in MCTs are suitable indicators predicting the risk of MT of MCT to SCC. CONCLUSION: Similar to general epithelial ovarian cancers, the early detection of MT of MCT to SCC is critical to long-term survival. Therefore, older patients with a large tumor or those with a tumor containing a solid component in a clinically diagnosed MCT should be evaluated to exclude potential MT to SCC.