大肠癌（CRC）在50岁以下的成年人中较为罕见，因此该人群可能会延迟治疗，导致癌症晚期和生存率较低。本研究旨在调查50岁以下 CRC 年轻成年人在就医至治疗之间的时间与生存率之间是否存在关联。本回顾性队列研究使用了加拿大安大略省联合人口基础数据，研究对象是于 2007 年至 2018 年间在安大略省内被诊断为 CRC 的50岁以下患者。分析于2019年12月至2022年12月间进行。调查使用行政和计费编码来确定首次就医至治疗开始之间的天数（总体间隔）。采用受限制立方样条回归来探讨总体间隔增加与总体生存率（OS）和病因特异性生存率（CSS）之间的关联。同时，针对 OS 和 CSS 进行多变量 Cox 比例风险模型拟合，考虑混杂因素。对于低紧急性子集的患者，该分析被重复进行。低紧急性子集的定义是指未紧急就诊、无转移性疾病、首次就医后14天内未进行断层扫描或内窥镜检查，并且总体间隔持续的至少28天。 在包括5026名患者的研究对象中，中位数（IQR）年龄为44.0岁（40.0-47.0岁）；其中2412人（48.0%）为女性；1266人（25.2%）患有转移性疾病，1570人（31.2%）患有直肠癌。低紧急性子集共包括2548名患者。总体间隔的中位数（IQR）为108天（55-214天）（15.4周[7.9-30.6周]）。与病情较轻者相比，转移性 CRC 患者的总体间隔中位数（IQR）较短（83天[39-183天]）。5年总体生存率为69.8%（95% CI，68.4%-71.1%）。样条回归显示，总体间隔较短的年轻患者（<108天）的 OS 和 CSS 较差，而总体间隔较长并没有明显的不利结果。在经过调整的 Cox 模型中，与等待12至18周者相比，总体间隔超过18周并未显著影响 OS 或 CSS（OS：HR，0.83 [95% CI，0.67-1.03]；CSS：HR，0.90 [95% CI，0.69-1.18]）。在低紧急性患者子集和分期分组中，结果相似。 在这项关于安大略省5026名50岁以下 CRC 患者的队列研究中，就医至治疗的时间与癌症晚期或低生存率无关。这些结果表明，在人群水平上，针对就医后时间间隔可能不会带来改善的结果。

Colorectal cancer (CRC) is uncommon in adults younger than 50 years of age, so this population may experience delays to treatment that contribute to advanced stage and poor survival.To investigate whether there is an association between time from presentation to treatment and survival in younger adults with CRC.This retrospective cohort study used linked population-based data in Ontario, Canada. Participants included patients with CRC aged younger than 50 years who were diagnosed in Ontario between 2007 and 2018. Analysis was performed between December 2019 and December 2022.Administrative and billing codes were used to identify the number of days between the date of first presentation and treatment initiation (overall interval).The associations between increasing overall interval, overall survival (OS), and cause-specific survival (CSS) were explored with restricted cubic spline regression. Multivariable Cox proportional hazards models were also fit for OS and CSS, adjusted for confounders. Analyses were repeated in a subset of patients with lower urgency, defined as those who did not present emergently, did not have metastatic disease, did not have cross-sectional imaging or endoscopy within 14 days of first presentation, and had an overall interval of at least 28 days duration.Among 5026 patients included, the median (IQR) age was 44.0 years (40.0-47.0 years); 2412 (48.0%) were female; 1266 (25.2%) had metastatic disease and 1570 (31.2%) had rectal cancer. The lower-urgency subset consisted of 2548 patients. The median (IQR) overall interval was 108 days (55-214 days) (15.4 weeks [7.9-30.6 weeks]). Patients with metastatic CRC had shorter median (IQR) overall intervals (83 days [39-183 days]) compared with those with less advanced disease. Five-year overall survival was 69.8% (95% CI, 68.4%-71.1%). Spline regression showed younger patients with shorter overall intervals (<108 days) had worse OS and CSS with no significant adverse outcomes of longer overall intervals. In adjusted Cox models, overall intervals longer than 18 weeks were not associated with significantly worse OS or CSS compared with those waiting 12 to 18 weeks (OS: HR, 0.83 [95% CI, 0.67-1.03]; CSS: HR, 0.90 [95% CI, 0.69-1.18]). Results were similar in the subset of lower-urgency patients, and when stratified by stage.In this cohort study of 5026 patients with CRC aged younger than 50 years of age in Ontario, time from presentation to treatment was not associated with advanced disease or poor survival. These results suggest that targeting postpresentation intervals may not translate to improved outcomes on a population level.