2769 - Outcome Comparisons and Patterns of Failure in Women with FIGO Stage I-II Uterine Clear Cell Carcinoma after Adjuvant Chemotherapy and Radiation Therapy

Purpose/Objective(s): Limited data exist on the optimal adjuvant treatment regimen for women with early-stage uterine clear cell carcinoma (CCC). This study aims to investigate recurrence patterns and survival outcomes in these patients after different adjuvant managements. The hypothesis is that there is no difference in outcomes or patterns of failure for patients with early stage uterine CCC who received adjuvant therapies compared to those who underwent observation.

Materials/Methods: Following IRB approval, our database was queried for patients who underwent surgical staging from 1/1990 to 11/2024 with 2009 FIGO stage I-II uterine clear cell carcinoma at our institution. After surgical staging, patients either underwent observation, adjuvant chemotherapy alone (carboplatin and paclitaxel), adjuvant radiation therapy (RT) alone (vaginal cuff HDR brachytherapy and/or pelvic external beam), or both adjuvant chemotherapy and RT. Patients with synchronous malignancies were excluded. Recurrence-free (RFS), disease-specific (DSS), and overall survival (OS), along with recurrence patterns, were analyzed. Multivariable Cox proportional hazards regression identified predictors for these survival endpoints.

Results: A total of 65 patients (median age: 65, median follow-up: 114 months) were included. Most patients had stage IA disease (66%) and negative pelvic lymph node evaluation (94%). 20 patients (31%) were managed with observation, 13 patients (20%) received RT alone, 7 patients (11%) received chemotherapy alone, and 25 patients (38%) received chemotherapy and RT. Nineteen out of 20 patients who were managed with observation had neither any myometrial invasion nor lymphovascular space invasion (LVSI). Recurrence occurred in 11 patients (17%), with distant recurrence as the most common first site (55%), followed by pelvic only recurrence in 3 patients (27%). There was no significant difference in recurrence rate (p = 0.39), distant recurrence (p = 0.30), or pelvic recurrence (p = 0.13) between the four groups with different adjuvant management. Additionally, there was no difference in 5-year RFS (observation 94.4%, RT alone 82.5%, chemotherapy alone 66.7%, chemotherapy and RT 89.2%, p = 0.55), 5-year DSS (observation 94.4%, RT alone 82.5%, chemotherapy alone 66.7%, chemotherapy and RT 94.1%, p = 0.21), and 5-year OS (observation 94.4%, RT alone 65.6%, chemotherapy alone 66.7%, chemotherapy and RT 89.6%, p = 0.088). The presence of LVSI was an independent predictor for worse RFS (HR 6.13, p = 0.023) and worse DSS (HR 6.26, p = 0.043). Only older age predicted worse OS (HR 1.08, p = 0.022).

Conclusion: Our data suggests there is no difference in survival endpoints in women with early stage uterine CCC after surgical staging and different adjuvant management approaches. Multi-institutional pooled analysis is warranted to study the impact of adjuvant therapies in this population with this rare pathology.