BACKGROUND Adjuvant chemotherapy is relatively underused in older patients with colon cancer in Japan, and its age-specific effects on clinical outcomes remain unclear. This study aimed to assess the effect of adjuvant chemotherapy on survival benefit in stage III colon cancer patients stratified by age in a Japanese real-world setting. METHODS In this multi-center retrospective cohort study, we analyzed patient-level information through a record linkage of population-based cancer registry data and administrative claims data. The study population comprised patients aged ≥18 years who received a pathological diagnosis of stage III colon cancer and underwent curative resection between 2010 and 2014 at 36 cancer care hospitals in Osaka Prefecture, Japan. Patients were divided into two groups based on age at diagnosis (< 75 and ≥ 75 years). The effect of adjuvant chemotherapy was analyzed using Cox proportional hazards regression models for all-cause mortality with inverse probability weighting of propensity scores. Adjusted hazard ratios were estimated for both age groups. RESULTS A total of 783 patients were analyzed; 476 (60.8%) were aged < 75 years and 307 (39.2%) were aged ≥75 years. The proportion of older patients who received adjuvant chemotherapy (36.8%) was substantially lower than that of younger patients (73.3%). In addition, the effect of adjuvant chemotherapy was different between the age groups: the adjusted hazard ratio was 0.56 (95% confidence interval: 0.33-0.94, P = 0.027) in younger patients and 1.07 (0.66-1.74, P = 0.78) in older patients. CONCLUSIONS The clinical effectiveness of adjuvant chemotherapy in older patients with stage III colon cancer appears limited under current utilization practices.

中文翻译：

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一项辅助化疗对按年龄分层的III期结肠癌患者的生存获益的影响：一项日本真实世界的队列研究。

背景技术辅助化疗在日本的老年结肠癌患者中使用相对较少，并且其对临床结果的针对年龄的影响仍不清楚。这项研究旨在评估辅助化疗对日本现实世界中按年龄分层的III期结肠癌患者生存获益的影响。方法在这项多中心回顾性队列研究中，我们通过基于人群的癌症登记数据与行政索赔数据的记录链接分析了患者水平的信息。研究人群包括年龄≥18岁的患者，他们在2010年至2014年间在日本大阪府的36家癌症护理医院接受了III期结肠癌的病理诊断，并接受了根治性切除。根据诊断时的年龄（<75岁和≥75岁）将患者分为两组。使用Cox比例风险回归模型分析全因死亡率的辅助化疗效果，并用倾向评分的逆概率加权。估计了两个年龄段的调整后的危险比。结果共分析了783例患者。75岁以下的有476（60.8％）岁，≥75岁的有307（39.2％）。接受辅助化疗的老年患者比例（36.8％）大大低于年轻患者（73.3％）。此外，不同年龄组的辅助化疗效果也不同：年轻患者调整后的危险比为0.56（95％置信区间：0.33-0.94，P = 0.027），而老年患者为1.07（0.66-1.74，P = 0.78）。老年患者。