Survival Outcomes and Prognostic Predictors in Patients With Malignant Struma Ovarii

Abstract

Background: Malignant struma ovarii (MSO) is an extremely rare ovarian malignant tumor and there is limited data on the survival outcomes and prognostic predictors of MSO. The objectives of this study were to investigate the disease-free survival (DFS), overall survival (OS), and disease-specific survival (DSS) rates of patients with MSO, and also evaluate the prognostic factors in this population.Methods: A retrospective study was conducted and 194 cases of MSO were selected. DFS was assessed by the logistic regression, OS by the Kaplan–Meier method, and DSS was evaluated by the Cox regression.Results: The median age of these patients was 46.0 years; 142 cases (73.2%) were confined to the ovary and 52 cases (26.8%) had extraovarian metastasis at the initial diagnosis of MSO. During the follow-up, 75.3% of these patients showed no evidence of disease and 18.0% were alive with disease. Only 13 deaths occurred, with 10 attributed to MSO. The 5, 10, and 15-year OS rates were 91.4, 87.7, and 83.5%, respectively. The 5, 10, and 15-year DSS rates were 93.8, 90.0, and 85.7%, respectively. Logistic regression revealed that International Federation of Gynecology and Obstetrics (FIGO) stage IV was the only risk factor for DFS [p < 0.001; odds ratio (OR) 7.328; 95% CI 3.103–16.885, FIGO stage IV vs. stage I; p = 0.021; OR 4.750, 95% CI 1.264–17.856, FIGO stage IV vs. stage II-III]. The multivariate Cox regression analysis showed that poor differentiation was the only risk factor for both OS (p = 0.005, OR 6.406; 95% CI 1.730–23.717) and DSS (p = 0.001, OR 9.664; 95% CI 2.409–38.760), while age ≥45 years was the prognostic predictor for OS (p = 0.038, OR 4.959; 95% CI 1.093–22.508).Conclusion: Survival outcomes were excellent in patients with MSO, irrespective of the treatment strategy, FIGO stage IV, age ≥45 years, and poor differentiation of tumors were the independent risk factors.

Presentation and treatment of two cases of malignant struma ovarii

“…SO is a highly specialized form of mature ovarian teratoma consisting of thyroid tissue showing all histological features of the thyroid gland. Depending on the histologic features, struma ovarii can be classified as benign or malignant; the diagnostic criteria for MSO are similar to those for differentiated thyroid cancer [ 4 , 10 , 11 , 14 ]. Features indicative of malignancy include cytologic atypia, nuclear grooves, “ground-glass” overlapping nuclei, increased mitotic activity, and vascular invasion [ 4 , 10 ].…”

“…Sijian et al demonstrated an excellent survival outcome in patients with MSO irrespective of the treatment strategy. Advanced stage disease (stage IV), age more than 55 years and poorly differenced tumour were independent risk factors of prognosis in patients with MSO [ 14 ]. Similarly, Cui et al reported a 4.72% mortality rate among 127 patients and most of the death occurred in patients with distant metastasis [ 4 ].…”

Incidence, clinical characteristics, and survival outcomes of ovarian strumal diseases: a retrospective cohort study

“…Nevertheless, RAI was widely recommended in metastatic MSO for ablation of residual diseases [ 25 , 26 , 28 ], and it may be the only practical therapeutic option in patients with unresectable diseases, such as multiple liver, lung, or bone metastases [ 29 ]. Although the exact therapeutic response rate for RAI in MSO was unavailable due to the extreme rarity and most patients received both surgery with RAI [ 15 ]. Some patients achieved stable diseases or complete remission with RAI therapy alone [ 30 – 33 ].…”

Metastatic follicular carcinoma arising from struma ovarii

“…Some authors raised the possibility that the size of the carcinomatous component rather than the size of the strumal component might have a prognosticative value in patients with MSO 12. Other poor prognostic findings that have been proposed include the presence of adhesions, ascites of 1 L or more, and ovarian serosal rent27 or FIGO stage IV disease, age 45 years or older, and poorly differentiated tumour 29. One study did not identify any potential risk factors in MSO confined to the ovary 12…”