目前，II 期结肠癌 (CC) 根治性手术后辅助化疗 (ACT) 的患者选择并不理想，导致高风险患者的过度治疗和低风险患者的治疗不足。术后循环肿瘤 DNA (ctDNA) 可以改善 ACT 患者的选择。我们对荷兰 II 期 CC 中 ctDNA 指导的 ACT 选择的（成本）有效性进行了早期基于模型的评估，以评估成本条件有效实施。经过验证的马尔可夫模型模拟了 1000 名 II 期 CC 患者从诊断到死亡的整个过程，并补充了 ctDNA 数据。评估了五种 ACT 选择策略：当前指南（pT4、pMMR）、仅 ctDNA，以及以不同方式将 ctDNA 状态与 pT4 和 pMMR 状态相结合的三种策略。对于每种策略，均估算了成本、生命年、质量调整生命年 (QALY)、复发率和 CC 死亡人数。进行敏感性分析以评估 ctDNA 检测成本、策略依从性、ctDNA 作为预测生物标志物以及 ctDNA 检测性能的影响。模型预测显示，与当前指南相比，仅 ctDNA 策略的效果较差（复发率为 2.2%） ，-0.016 QALY），而联合策略更有效（-3.6% 复发率，0.038 QALY）。组合策略并不具有成本效益，因为增量成本效益比为每 QALY 67,413 欧元，超过了每 QALY 50,000 欧元的支付意愿门槛。敏感性分析表明，如果 ctDNA 检测成本低于 1500 欧元，或者如果 ctDNA 状态可以预测治疗反应，或者如果 ctDNA 检测性能大幅改善，则组合策略将具有成本效益。将 ctDNA 添加到当前的高风险临床病理中特征（pT4 和 pMMR）可以改善 ACT 患者的选择，并且也可能具有成本效益。未来的研究应调查术后 ctDNA 状态的预测价值，以准确评估 ctDNA 检测对第二阶段 ACT 决策的成本效益 CC。© 作者，2024 年。

Current patient selection for adjuvant chemotherapy (ACT) after curative surgery for stage II colon cancer (CC) is suboptimal, causing overtreatment of high-risk patients and undertreatment of low-risk patients. Postoperative circulating tumor DNA (ctDNA) could improve patient selection for ACT.We conducted an early model-based evaluation of the (cost-)effectiveness of ctDNA-guided selection for ACT in stage II CC in the Netherlands to assess the conditions for cost-effective implementation.A validated Markov model, simulating 1000 stage II CC patients from diagnosis to death, was supplemented with ctDNA data. Five ACT selection strategies were evaluated: the current guideline (pT4, pMMR), ctDNA-only, and three strategies that combined ctDNA status with pT4 and pMMR status in different ways. For each strategy, the costs, life years, quality-adjusted life years (QALYs), recurrences, and CC deaths were estimated. Sensitivity analyses were performed to assess the impact of the costs of ctDNA testing, strategy adherence, ctDNA as a predictive biomarker, and ctDNA test performance.Model predictions showed that compared to current guidelines, the ctDNA-only strategy was less effective (+2.2% recurrences, -0.016 QALYs), while the combination strategies were more effective (-3.6% recurrences, +0.038 QALYs). The combination strategies were not cost-effective, since the incremental cost-effectiveness ratio was €67,413 per QALY, exceeding the willingness-to-pay threshold of €50,000 per QALY. Sensitivity analyses showed that the combination strategies would be cost-effective if the ctDNA test costs were lower than €1500, or if ctDNA status was predictive of treatment response, or if the ctDNA test performance improved substantially.Adding ctDNA to current high-risk clinicopathological features (pT4 and pMMR) can improve patient selection for ACT and can also potentially be cost-effective. Future studies should investigate the predictive value of post-surgery ctDNA status to accurately evaluate the cost-effectiveness of ctDNA testing for ACT decisions in stage II CC.© The Author(s), 2024.