Malignant transformation of mature cystic teratoma of the ovary: 30-year experience of a single tertiary care center.

Objective: To review the authors' experience with this rare disease and describe their management modality and the outcome. Material and Methods: From January 1983 to December 2013, 13 patients with malignant transformation arising in ovarian MCT were treated at the Division of Gynecologic Oncology in the University of Manitoba. Demographic characteristics, symptoms, signs, stage, mode of therapy, and results of follow-up were reviewed retrospectively. Results: Median age at diagnosis was 53 years (range 25-65). The most common presenting symptom was a palpable mass in nine cases. Squamous cell carcinoma (SCC) was found in 38% (five cases), adenocarcinoma in 15% (two cases), anaplastic carcinoma in 8% (one case), and papillary thyroid carcinoma in 38% (five cases). Eight cases were Stage I, two cases were Stage II, and three cases were Stage III. All patients underwent surgery. Five patients received adjuvant treatment with platinum-based chemotherapy + pelvic radiation. Four patients had recurrent disease (two SCC and two adenocarcinoma). Three patients died of disease after recurrence. The median follow up period of the entire patient population was 60 months, with a three-year overall survival of 76%. Conclusion: Malignant transformation of MCT is large ovarian tumors that mainly occur in patients in their fifth and sixth decades of life. They often present as incidental pathologic findings after surgery for MCT. SCC has traditionally been the most common pathology, however in the present series, the authors found that papillary thyroid carcinoma was equally common. Platinum-based chemotherapy with pelvic radiation in early stage (including Stage IA) and locally recurrent disease should be offered. Advanced stages and mutinous adenocarcinoma represent a poorer prognosis despite adjuvant treatment. In patients with papillary thyroid carcinoma, conservative surveillance in early stage and adjuvant total thyroidectomy with radioactive iodine treatment in advanced stage disease appears to be an effective treatment.