Primary tumor sidedness (PTS) is an independent prognostic factor in patients with metastatic colorectal cancer (CRC), with a worse prognosis for right-sided tumors. There are limited data on the prognostic impact of PTS in stage III CRC. The main objective of this study was to analyze the prognostic impact of PTS in stage III CRC. A retrospective and uni-institutional cohort study was performed in an oncology reference center. Patients with stage III CRC treated with a 5-fluorouracil and oxaliplatin-based chemotherapy regimen (mFLOX regimen) from October 2007 to February 2013 were included. The primary outcome was the probability of overall survival (OS) at 5 years stratified by PTS. Secondary outcomes were the probability of disease-free survival (DFS) at 5 years and an analysis of the prognostic impact of clinical and molecular biomarkers. Kaplan‒Meier curves were used, and Cox models were used to evaluate prognostic factors associated with OS and DFS. Overall, 265 patients were evaluated. Transverse colon tumors, multicentric tumors, and undetermined primary subsites were excluded, resulting in 234 patients classified according to PTS: 95 with right sidedness (40.6%) and 139 with left sidedness (59.4%). The median follow-up time was 66 months [interquartile range (IQR): 39-81]. The 5-year OS probabilities for right-sided and left-sided tumors were 67% (95% CI: 58%-77%) and 82% (75%-89%), respectively [hazard ratio (HR): 2.02, 95% CI: 1.18-3.46; = .010]. The 5-year probabilities of DFS for right-sided and left-sided tumors were 58% (49%-69%) and 65% (58%-74%), respectively (HR: 1.29, 0.84-1.97; = 0.248). These data suggest that there may be a worse prognosis (inferior OS at 5 years) for resected right-sided stage III CRC patients treated in the real world. However, these data need to be confirmed by prospective studies with a larger number of participants.

中文翻译：

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原发肿瘤单侧性对 III 期结直肠癌预后的影响：来自巴西队列的真实世界证据

原发性肿瘤侧面性（PTS）是转移性结直肠癌（CRC）患者的独立预后因素，右侧肿瘤的预后较差。关于 PTS 对 III 期 CRC 预后影响的数据有限。本研究的主要目的是分析 PTS 对 III 期 CRC 的预后影响。在肿瘤学参考中心进行了一项回顾性单机构队列研究。纳入2007年10月至2013年2月接受基于5-氟尿嘧啶和奥沙利铂的化疗方案（mFLOX方案）治疗的III期CRC患者。主要结局是按 PTS 分层的 5 年总生存 (OS) 概率。次要结局是 5 年无病生存 (DFS) 的概率以及临床和分子生物标志物的预后影响分析。使用 Kaplan-Meier 曲线和 Cox 模型来评估与 OS 和 DFS 相关的预后因素。总体而言，对 265 名患者进行了评估。排除横结肠肿瘤、多中心肿瘤和未确定的原发亚位点，根据 PTS 分类 234 例患者：95 例右侧肿瘤（40.6%），139 例左侧肿瘤（59.4%）。中位随访时间为 66 个月 [四分位距 (IQR)：39-81]。右侧和左侧肿瘤的 5 年 OS 概率分别为 67% (95% CI: 58%-77%) 和 82% (75%-89%) [风险比 (HR): 2.02， 95% CI：1.18-3.46；=.010]。右侧和左侧肿瘤的 5 年 DFS 概率分别为 58% (49%-69%) 和 65% (58%-74%)（HR：1.29、0.84-1.97；= 0.248） 。这些数据表明，在现实世界中接受治疗的切除的右侧 III 期 CRC 患者的预后可能更差（5 年 OS 较差）。然而，这些数据需要通过更多参与者的前瞻性研究来证实。