Introduction/Background Small-cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is an aggressive malignancy that accounts for less than 0.01% of ovarian cancers. First-line treatment options include surgical cytoreduction, vinblastine, cisplatin, cyclophosphamide, bleomycin, doxorubicin, and etoposide (VPCBAE) combination regimens, and high-dose chemotherapy (HDC) with autologous stem cell transplantation. We aimed to assess the prognostic impact of different first-line treatment modalities in our patient cohort.

Methodology A retrospective review of SCCOHT evaluated at the Mayo Clinic from 1994 to 2022 was conducted. Recurrence-free survival (RFS) was measured from the date of diagnosis to the date of recurrence, death, or last follow-up, whichever came first. Log-rank test was used to compare survival, after stratification by stage.

Results Twenty-eight cases were identified:

13 patients (46.4%) with stage I-II and 15 (53.6%) with stage III-IV disease. The median age at diagnosis was 28 years [IQR 23–34]. Sixteen relapses and 15 deaths were reported. RFS was significantly different between early and advanced disease (median RFS 13.0 vs. 3.7 months; p<0.01). In advanced disease, macroscopic complete resection (n=6/13) and VPCBAE (n=6/12) appeared to increase RFS, but the difference was not statistically significant (p=0.08 and 0.24, respectively), due to limited power. A longer RFS (10.0 vs. 3.6 months; p-value=0.01) was observed in HDC with autologous stem cell transplantation (n=4/13), after surgery and adjuvant chemotherapy. In early-stage disease, radical surgery (n=8/13) (vs. unilateral salpingo-oophorectomy only) and VPCBAE (n=4/10) tended to increase survival but did not reach statistical significance (p=0.85 and 0.76, respectively).

Conclusion Stage is a strong prognostic factor in SCCOHT. HDC with autologous stem cell transplantation could be offered to patients with good performance status and awareness of its debilitating toxicities. Surgical complete resection, type of adjuvant chemotherapy, and conservative treatment require further evidence. International cooperation and centralization of care are essential for this rare ovarian cancer that affects young women.

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Abstract #82 Figure 1

Oncologic outcomes and first-line treatment characteristics of Small Cell Carcinoma of the Ovary, Hypercalcemic type evaluated at Mayo Clinic, Rochester. Each line represents a patient. Abbreviations: CHT, chemotherapy; HDC, high-dose chemotherapy (HDC) with autologous stem cell transplantation; RD, residual disease; VPCBAE, vinblastine, cisplatin, cyclophosphamide, bleomycin, doxorubicin, and etoposide

Disclosures Nothing to disclose.