2992 - Effect of Blood Uric Acid on Tumor Regression Response to Preoperative Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer

L. He¹, G. Liu², S. Li¹, H. Guo¹, P. Xie¹, H. Luo³, Q. Zhang⁴, X. Wei⁵, Y. Teng⁶, and X. Wang^4,7; ¹The First School of Clinical Medicine, Lanzhou University, The First Hospital of Lanzhou University, Lanzhou, Gansu, China, ²School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China, ³Heavy Ion Therapy Center, Lanzhou Heavy Ions Hospital, Lanzhou, Gansu, China, ⁴Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu, China, ⁵Mianyang Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Mianyang, Sichuan, China, ⁶Department of Urology, Mianyang Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Mianyang, Sichuan, China, ⁷The First School of Clinical Medicine, Lanzhou University, Lanzhou, Gansu, China

Purpose/Objective(s): Preoperative neoadjuvant chemoradiotherapy (nCRT) and total mesorectal excision (TME) are the main therapeutic modalities for the treatment of locally advanced rectal cancer (LARC), but the tumor response rate after treatment is variable. The relationship between uric acid and the development and progression of a variety of tumors, as well as patient prognosis, has been extensively studied and found to be significant. This study aimed to determine the influence of blood uric acid levels on tumor response in LARC patients undergoing preoperative nCRT.

Materials/

Methods: This study retrospectively analyzed patients with LARC who received preoperative nCRT and then underwent curative resection at one institution from 1/1/2019 to 12/2/2023. The evaluation indexes of the study included the tumor regression grade (TRG), T downgrade, and pathological complete response (pCR), as well as the fasting blood uric acid level during the preoperative chemoradiotherapy of the patients. Gender-specific thresholds for hyperuricemia were established as >420 µmol/L for men and >360 µmol/L for women. Treatment response was evaluated using histologic quantification according to the AJCC 8th edition TRG criteria for rectal cancer, as well as pre- and post-treatment T grades and pCR.

Results: The study included 135 patients with LARC who received preoperative nCRT and curative resection. This group comprised 12 women and 31 men diagnosed with hyperuricemia. The radiotherapy regimen consisted of 1.8-2 Gy/dose, 5 times/week, with a total dose of 45-50.4 Gy, along with concurrent oral capecitabine chemotherapy on the same day of radiotherapy (825 mg/m2, oral, bid). The chemotherapy included XELOX and mFOLFOX6. Analysis of blood uric acid levels showed a significant correlation with TRG (P=0.033) and pT (P=0.010), especially in hyperuricemic patients, who showed significant differences in TRG, T downgrading, pCR, and pT grading compared to non-hyperuricemic patients (P<0.05). Multifactorial analysis confirmed that hyperuricemia was an independent risk factor for TRG (P=0.007), and higher blood uric acid levels were associated with worse tumor response (P=0.002).

Conclusion: Hyperuricemia could potentially impact tumor regression response to preoperative nCRT in LARC patients as an independent risk factor. A significant correlation exists between elevated blood uric acid levels and an unfavorable tumor regression response. Hence, it is recommended that clinicians assess a patients blood uric acid level when developing a treatment plan and potentially incorporate methods to enhance the efficacy of nCRT.