40 Comparison of contemporary management and outcomes of patients with transitional cell carcinomas and malignant Brenner tumors of the ovary

To compare demographics, management, and outcomes for patients (pts) with ovarian transitional cell carcinomas (TCC) and malignant Brenner tumors (MBT) This was a retrospective cohort study of pts with ovarian TCC and MBT (malignant subtypes of transitional cell neoplasms) registered in the SEER 17 research plus database from 2000–2019. Patient and tumor characteristics were compared and relative risks determined. SEER historic stage was used for risk adjustment. Relative survival (RS) was calculated by Kaplan Meier's method. RS is defined as the ratio of the probability of survival in a group of pts with cancer to the expected probability of survival in a comparable group of pts without cancer, and represents cancer survival in the absence of other causes of death We identified 188 pts with MBT and 272 pts with TCC. There were no significant differences in race or age at diagnosis; 97% of pts in both cohorts had surgery. Rates of lymphadenectomy were similar: 60.9% MBT and 64.5% TCC. MBT presented more frequently with localized disease than TCC (60.9% vs 16.8%, RR 3.61. 95% CI 2.58–5.07, p<0.001). Pts with MBT were less likely to receive chemotherapy than TCC; 45.7% vs 73.5% (RR 0.62, 95% CI 0.52–0.74 p<0.0001). This difference primarily was associated with frequency of localized disease: 27.4% of early stage MBT compared to 60.6% of early stage TCC had chemotherapy (RR 0.45, 95% CI 0.29–0.70, p=0.0004). Most pts (63.0% MBT and 79.1 %TCC) with metastatic disease received chemotherapy, although somewhat less often in MBT than TCC with metastatic disease (RR = 0.80, 95% CI = 0.64 to 0.99, p=0.04.). When adjusted for stage, we found no significant difference in RS between TCC and MBT; 5-year RS was 67.8% (95% CI 60-74.5) for TCC and 63.3% (95% CI 53.1–71.9) for MBT. Nearly a third of pts were not included in survival analyses due to incomplete follow up Despite similar origin and histologic appearance, there are clinically relevant features that distinguish between TCC and MBT. In agreement with older literature, we found differences in extent of disease at presentation. We also found that distinct treatment paradigms have developed, particularly among patients with localized disease.