The Benefits of Adjuvant Chemotherapy for Upper Tract Urothelial Carcinoma Require at Least Three Cycles

[ABSTRACT] [Background] Upper urinary tract urothelial carcinoma (UTUC) is uncommon. In advanced cases, radical nephroureterectomy (RNU) alone is not curative, and recurrence and metastasis are likely to occur. Adjuvant chemotherapy (AC) is an evidence-based treatment. However, the optimal number of AC cycles is not clear. This multicenter study investigated the number of cycles required for the beneficial effects of AC in Japanese patients with UTUC. [Methods] Patients who were diagnosed with UTUC and underwent RNU at our hospital and affiliated hospitals from January 2010 to September 2020 were included in the study. Patients with pathological T3 or higher or lymph node metastasis were observed or given AC, and their responses were compared. The AC regimens included gemcitabine and cisplatin or carboplatin. Patients were also classified into two groups : the observation and two cycles of AC group and the three to four cycles of AC group. The survival curves for recurrence-free survival (RFS) and cancer-specific survival (CSS) were evaluated using Kaplan-Meier analyses. [Results] Of the 133 patients enrolled in the study, 24 received 2 cycles of AC, 37 received 3-4 cycles, and 72 were observed only. The 5-year RFS was 67.1% for the 3-4 cycles of AC group and 41.7% for the observation and two cycles of AC group. The 5-year CSS was 72.2% for the 3-4 cycles of AC group and 35.9% for the observation and two cycles of AC group. RFS and CSS were significantly longer in the 3-4 cycles of AC group compared to the observation and 2 cycles group (P = 0.048 and P = 0.005 respectively). [Conclusion] AC prolonged RFS and CSS in the real-world setting. However, at least three cycles of AC are required to achieve beneficial effects in patients with UTUC.