在弥漫性大B细胞淋巴瘤（DLBCL）中，积极的中期正电子发射断层扫描（PET）预示治疗失败，但通过此方式识别出的高风险患者比例很小。为了提高预测能力，我们将中期PET结果与伴随的IgM型免疫球蛋白G病合并起来。在一项前瞻性试验中，共有108例DLBCL患者参与，其中9例（8％）中期PET积极，19例（18％）有IgM型免疫球蛋白G病。单克隆蛋白与区分的遗传特征无关，其轻链限制与淋巴瘤的轻链限制并不总是一致的。通过中期PET和IgM型免疫球蛋白G病提供的信息，将人群分为存在较大风险（1-2不良因素）和低风险（无不良因素）的两个组，其结果差异很大（人群规模，25％与75％；3年进展风险，51％与10％；3年总体生存率，64％与95％）。包括已知风险因素在内的多变量分析显示，中期PET结果和IgM型免疫球蛋白G病状态是与预后显著相关的唯一因素。关于中期PET反应和IgM型免疫球蛋白G病的信息可能对测试风险适应性治疗策略的研究有用。© 2023. 作者。

In diffuse large B-cell lymphoma (DLBCL), a positive interim positron emission tomography (PET) scan predicts treatment failure, but the proportion of high-risk patients thus identified is small. To improve prediction, we combined the interim PET result with the presence or absence of an associated IgM gammopathy. Of 108 DLBCL patients participating in a prospective trial, nine (8%) were interim PET positive and 19 (18%) had an IgM gammopathy. The monoclonal protein was not associated with distinguishing genetic features, and its light chain restriction was not always concordant with the light chain restriction of the lymphoma. The information provided by interim PET and IgM gammopathy was combined to dichotomize the population into sizeable high-risk (1-2 adverse factors) and low-risk groups (no adverse factor) with widely different outcomes (population size, 25% vs. 75%; 3-year risk of progression, 51% vs. 10%; 3-year overall survival, 64% vs. 95%). Multivariable analyses including established risk factors revealed the interim PET result and the IgM gammopathy status to be the only factors significantly associated with outcome. Information about interim PET response and IgM gammopathy may be useful in studies testing risk-adapted treatment strategies.© 2023. The Author(s).