3221 - The Effectiveness of Radiotherapy for Upper Tract Urothelial Carcinoma (UTUC) with Lymph Node Metastasis and Optimal Target Delineation for Clinical Target Volume

X. Li, X. Gao, H. Li, X. Qi, and M. W. Ma; Department of Radiation Oncology, Peking University First Hospital, Beijing, China

Purpose/Objective(s): The effectiveness of radiotherapy for upper tract urothelial carcinoma (UTUC) with lymph node metastasis or recurrence, as well as the appropriate clinical target volume (CTV) for lymph node recurrent UTUC, are currently ambiguous.This study prospectively analyzed the efficacy of radiotherapy in patients with clinically positive lymph nodes in UTUC. Additionally, we identified the specific region of local recurrence in UTUCs located at different primary tumor sites to aid in defining the CTV for radiotherapy Materials/

Methods: From January 2020to April 2023, all patients with UTUC who underwent radical surgery at Peking university first hospital were enrolled.In this prospective study, we identified 114 UTUC patients who had recurrent lymph nodes or tumor bed recurrence in the abdominal and pelvic areas after radical surgery. All patients had medical CT or MRI images for review, and 64.04% of them had PET imaging.
Results: The median recurrence time after surgery was 9 months(1-108). 22 patients had synchronous distant metastasis,while 92 patients were only clinically abdominal and pelvic lymph node metastasis. A total of 321 recurrent lymph nodes in the abdominal or pelvic regions were observed. The median number of recurrent lymph nodes was 2 (range 1-11). In 92 patients with only abdominal and pelvic lymph node metastasis,9 of them refused any treatment,26 of them received only radiation therapy,18 of them received systemic therapy( chemotherapy or immunotherapy),39 of them received radiotherapy and systemic therapy.The median progression free survival time for four group were 5,35,9 and 30 months.Compared with only systemic therapy,radiotherapy and systemic therapy significantly improved the 1-year PFS(37.0% Vs 75.2%,P=0.001). The most frequent sites of recurrence were the para-aortic (71.1%) and common iliac (41.2%) regions in all patients. Patients with lower ureter tumors had a higher rate of internal (17.0%) and external (34.0%) iliac lymph node recurrence. Additionally, renal fossa recurrence was more likely among those with renal pelvis tumors (p=0.013). The recurrence rate was similar in the left para-aortic (LPA, 30.7%), aortocaval (AC, 40.7%) and right para-caval (RPC,27.8%) areas for right UTUC. Left UTUC patients had para-aortic region recurrence, mostly in the left para-aortic (LPA, 62.7%) and aortocaval (AC, 32.9%) areas, while recurrence in the right para-caval (RPC, 8.6%) area was rare.
Conclusion: Radiotherapy demonstrated a significant improvement in PFS for patients with clinically N+ UTUC. The combination therapy group showed a marked improvement in 1-year PFS when contrasted with those undergoing systemic therapy. The varied recurrence patterns observed in UTUC cases with different primary locations offer clinicians essential guidance in designing CTV for radiotherapy in UTUC cases with differing tumor locations.