Uterine serous carcinoma: Reassessing effectiveness of platinum-based adjuvant therapy

Objective: Two randomized trials failed to demonstrate efficacy of platinum-based chemotherapy (PbCT) for uterine serous carcinoma (USC). Our objective was to reassess the value of PbCT for patients with microscopic residuum (R0). Methods: Progression-free survival (PFS) after surgery was analyzed for 409 patients and correlated with adjuvant therapies: vaginal brachytherapy (VBRT), external beam radiotherapy (EBRT), PbCT, or combinations. Results: The estimated 5-year PFS for stage I (n = 209) USC was 65.1% for observation only; 90.7%, VBRT only; and 91.1%, PbCT ± VBRT (85% received VBRT); VBRT significantly (P =.004) impacted PFS, but the added value of PbCT remains uncertain. Of 58 stage IIIC, PbCT-treated patients (±EBRT), 5-year PFS was 33.9%; most failures had a vascular disseminated component. Median PFS for 72 stage IV, PbCT-treated patients was 18.6 months for R0; 8.0, R1 ≤ 1 cm residual disease; and 4.6, R2 > 1 cm (P =.008). The progression rate (PR) during 1 to 2 year follow-up for R0 was similar to PR during 0–1 year follow-up for R1 (P =.31), suggesting recurrences in patients with R0 disease before 2 years are likely platinum resistant. PRs during follow-up were nearly identical for R0 ≥ 2 years and R1 ≥ 1 year (P =.95), presumably showing limited numbers of platinum-sensitive tumors. Conclusions: A comparison of PR for patients treated with PbCT for stage IV R0 and R1 disease suggested that a 1-year lag interval precedes clinical recognition of PbCT refractory/resistant R0 disease. Most patients treated with PbCT who had microscopic residuum had recurrences within 2 years (across stages), emphasizing the need for more effective therapy.