To the Editor The study by Garcia-Murillas and colleagues¹ suggests an association of detection of circulating tumor DNA (ctDNA) in patients treated for early-stage breast cancer with a high risk of disease recurrence. The authors conclude that 23 of 29 recurrences (79%) were ctDNA positive and that the mean clinical lead time between detection of ctDNA and relapse was 10.7 months (95% CI, 8.1-19.1 months). Garcia-Murillas et al¹ also found an association of detection of ctDNA at diagnosis with relapse-free survival (hazard ratio, 5.8; 95% CI, 1.2-27.1). They have shown that ctDNA levels varied in all breast cancer subtypes and were highest in triple-negative cancers, intermediate in ERBB2-positive cancers, and lowest in the estrogen receptor– and progesterone receptor–positive cancers. The presence of ctDNA during follow-up was associated with a shorter relapse-free period in all subtypes. The study validates the method of analyzing ctDNA by personalized digital polymerase chain reaction, in which the tumor mutations are assessed first and then similar mutations are searched for in the plasma of the patient on follow-up to detect molecular residual disease.

致编辑Garcia-Murillas及其同事^1的研究表明，在患有早期乳腺癌且疾病复发风险高的患者中，循环肿瘤DNA（ctDNA）的检测具有相关性。作者得出结论，29例复发中有23例（79％）是ctDNA阳性，并且从ctDNA检测到复发之间的平均临床前置时间为10.7个月（95％CI，8.1-19.1个月）。加西亚·穆里利亚斯（Garcia-Murillas）等人¹还发现诊断时检测ctDNA与无复发生存相关（危险比，5.8； 95％CI，1.2-27.1）。他们表明，ctDNA水平在所有乳腺癌亚型中均发生变化，在三阴性癌症中最高，在ERBB2阳性癌症中处于中间水平，在雌激素受体和孕激素受体阳性癌症中最低。随访期间ctDNA的存在与所有亚型的较短的无复发期有关。该研究验证了通过个性化数字聚合酶链反应分析ctDNA的方法，该方法首先评估肿瘤突变，然后在患者血浆中寻找相似的突变，以进行随访以检测分子残留疾病。