小细胞肺癌（SCLC）可分为基于转录因子的亚型（ASCL1、NeuroD1、POU2F3）。尽管体外研究表明这些标志物的表达存在肿瘤内异质性，但SCLC亚型在患者中随时间和位置变化的情况尚不清楚。我们在2006年至2022年期间在我们的医疗机构连续研究了一组患者，其中患者具有多个可获得的多个部位和/或时间点的福尔马林固定石蜡嵌埋的SCLC样本。利用免疫组织化学进行ASCL1、NeuroD1和POU2F3的染色和评估，使用H评分，根据最高H评分的阳性标志物（H评分阈值>10）确定亚型。来自84名患者（74名具有两个样本，10名具有两个以上样本）的179个样本（肺部75个，淋巴结51个，非淋巴结转移53个）包括98个（54.7%）ASCL1优势型、47个（26.3%）NeuroD1优势型、15个（8.4%）POU2F3优势型、17个（9.5%）三阴性和2个（1.1%）ASCL1/NeuroD1共优性样本。非肺部位置富集了NeuroD1优势亚型。对成对比较的亚型一致性在整体上为71.4%，在考虑ASCL1/NeuroD1双表达以及细胞数/slide<500、H评分阈值和样本脱钙等技术因素后为89.7%。在这个队列中，无论时间间隔较长还是体外与胸内样本相比，亚型一致性没有显著差异。在考虑技术因素后，基于转录因子的亚型在大约10%的患者的多个SCLC样本中不一致，与样本位置和时间间隔无关。我们的发现凸显了临床样本中SCLC的时空异质性以及可能限制SCLC基于转录因子的亚型一致性的技术和生物学因素的潜在挑战。© 2023 John Wiley & Sons Ltd.

Small cell lung carcinoma (SCLC) can be classified into transcription factor-based subtypes (ASCL1, NeuroD1, POU2F3). While in-vitro studies suggest intratumoral heterogeneity in the expression of these markers, how SCLC subtypes vary over time and among locations in patients remains unclear.We searched a consecutive series of patients at our institution in 2006-22 for those with greater than one available formalin-fixed paraffin-embedded SCLC sample in multiple sites and/or time-points. Immunohistochemistry for ASCL1, NeuroD1 and POU2F3 was performed and evaluated using H-scores, with subtype assigned based on the positive marker (H-score threshold >10) with the highest H-score. The 179 samples (75, lung; 51, lymph nodes; 53, non-nodal metastases) from 84 patients (74 with two, 10 with more than two samples) included 98 (54.7%) ASCL1-dominant, 47 (26.3%) NeuroD1-dominant, 15 (8.4%) POU2F3-dominant, 17 (9.5%) triple-negative and two (1.1%) ASCL1/NeuroD1 co-dominant samples. NeuroD1-dominant subtype was enriched in non-lung locations. Subtype concordance from pairwise comparison was 71.4% overall and 89.7% after accounting for ASCL1/NeuroD1-dual expressors and technical factors including <500 cells/slide, H-score thresholds and sample decalcification. No significant difference in subtype concordance was noted with a longer time lapse or with extrathoracic versus intrathoracic samples in this cohort.After accounting for technical factors, transcription factor-based subtyping was discordant among multiple SCLC samples in ~10% of patients, regardless of sample locations and time lapse. Our findings highlighted the spatiotemporal heterogeneity of SCLC in clinical samples and potential challenges, including technical and biological factors, that might limit concordance in SCLC transcription factor-based subtyping.© 2023 John Wiley & Sons Ltd.