Clinical characteristics and survival outcomes of malignant struma ovarii confined to the ovary

Abstract

Background Malignant struma ovarii (MSO) is a unique type of ovarian malignancy that data on the survival outcome is limited and management strategy remains controversial due to its extreme rarity. Methods To investigate the clinical characteristics and treatment options in patients with MSO confined to the ovary, while also evaluating the recurrent-free survival (RFS) and overall survival (OS) rate in this population, a retrospective study was conducted. One hundred twenty-five cases of MSO confined to the ovary were enrolled and their clinical characteristics, treatment strategies, and results of follow-up were analyzed. OS and RFS were assessed by Kaplan-Meier analyses and Cox regression models. Results The most common pathological subtype in this cohort was papillary carcinoma (44.8%). Other reported subtypes, in order of prevalence, were follicular variant of papillary carcinoma, follicular carcinoma, and mixed follicular-papillary carcinoma. Surgical treatment options varied in this cohort that 8.0% of the patients received ovarian cystectomy, 33.6% underwent unilateral salpingo-oophorectomy (USO), 5.6% received bilateral salpingo-oophorectomy (BSO), 21.6% received total abdominal hysterectomy with BSO (TAH/BSO), and 17.6% were treated with debulking surgery; 20.0% of them received radioiodine therapy (RAI). Twenty-seven patients experienced recurrence with a median RFS of 14.0 years (95% confidence interval [CI], 9.5–18.5). The 5-year and 10-year recurrent rate were 27.1, 35.2%, respectively. Eight patients died during follow-up, with five attributed to MSO; the 5-year, 10-year, and 20-year OS rate was 95.3, 88.7 and 88.7%, respectively. However, the univariate and multivariate Cox regression showed no potential risk factor for RFS and OS. Conclusion Patients with MSO confined to the ovary had an excellent survival outcome, despite varied treatment strategies, and the recurrent rate was relatively high. We recommend USO as the preferred surgical option in this population since more aggressive surgery does not improve outcomes and the benefits of RAI are uncertain.

Malignant Struma Ovarii Τreated With Cytoreductive Surgery (CRS) and Hyperthermic Intraperitoneal Chemotherapy (HIPEC)

“…Papillary thyroid carcinoma is the most common type of histology in the published literature (7). Our patient also had papillary thyroid carcinoma, and a struma ovarii originating from the left ovary, which was larger than 12 cm.…”

“…These features were all present at our patient with evidence of peritoneal metastasis on the preoperative CT record. Despite the fact that most germ cell tumors are chemosensitive, malignant struma ovarii responds poorly to chemotherapy (7); yet our patient responded well to 6 cycles of neoadjuvant chemotherapy, so that no vital extraovarian involvement was detectable on postoperative histology, only distinct fibrosis and scarring, which were originally peritoneal metastasis. As has been suggested by several authors in the literature, these implants may not be malignant peritoneal implants, but extremely well-differentiated "strumosis" corresponding to normal thyroid tissue (8,13,14).…”

“…Bilateral adnexectomy (5.6%) and ovarian cystectomy (8%) were performed in the minority of the cases. Examining the recurrence-free survival (5 year and 10 year RFS 27.1% and 35.2%, respectively) and overall survival, excellent survival rate was found regardless of the surgical management applied (5 year, 10 year, and 20 year OS rates were 95.3%, 88.7% and 88.7%, respectively) (7). As other authors have also suggested, in our treatment decision there was more extensive surgical intervention in case of postmenopausal patients than when fertility prevention is desired at younger patients at a reproductive age (6,9).…”

“…Furthermore, a recent retrospective study of 125 cases found ascites in only 17.6% and elevated levels of CA-125 in 36.4% of the cases (7). Another study of 88 patients found that ascites occurred without evidence of tumor in every patient where cytological reports were available, making preoperative diagnosis even more difficult (8).…”

Survival Outcomes and Prognostic Predictors in Patients With Malignant Struma Ovarii

“…Although their study included patients with and without metastasis, they did not evaluate risk factors for overall survival (OS). Our previous study found a similar OS rate in patients with MSO (confined to the ovary) and metastatic MSO ( 10 , 11 ). We found that age ≥55 years was a strong risk factor for OS in patients with metastatic MSO but did not find any statistically significant predictive factor for OS in patients with MSO confined to the ovary.…”