T-cell receptor beta constant 1 flow cytometry for diagnosing clonality in mature T-cell neoplasms: a systematic review and meta-analysis of diagnostic accuracy

Abstract Introduction Accurate assessment of T-cell clonality is key for diagnosing mature T-cell neoplasms. TRBC1-based flow cytometry provides a rapid, robust, and cost-efficient approach. This systematic review and meta-analysis assessed the diagnostic accuracy of TRBC1 flow cytometry (TRBC1-FC) for detecting T-cell clonality in mature T-cell neoplasms. Content We systematically searched Scopus, PubMed (MEDLINE), and Google Scholar for articles on TRBC1-FC diagnostic accuracy published up to July 1, 2025. Pooled sensitivity and specificity were estimated, between-study heterogeneity was evaluated and small-study effects were examined. Summary This meta-analysis included 10 studies. The pooled sensitivity was 97.6 % (95 % CI, 95.1–99.4 %) and specificity 90.7 % (95 % CI, 76.0–99.3 %). The pooled LR+ was 10.9 (95 % CI, 4.1–28.9), LR-was 0.053 (95 % CI, 0.025–0.12), and DOR 339 (95 % CI, 64–1,788). The HSROC curve demonstrated an AUC of 0.974 (partial AUC=0.970), confirming excellent global discriminatory capacity. Between-study heterogeneity was substantial (I 2 =83.3 %), mainly affecting specificity and DOR, while sensitivity remained highly consistent. No evidence of a threshold effect was found. Deeks’ test showed significant small-study effects (p<0.001), and sensitivity analyses identified one influential study whose exclusion markedly reduced heterogeneity. These results confirm the high diagnostic performance and robustness of TRBC1-FC for T-cell clonality assessment. Outlook TRBC1-FC demonstrates high sensitivity and low LR−, supporting its role as a rule-out test. Variability in specificity, LR+ and DOR, mainly due to small-study effects, advises caution for rule-in use. Standardized protocols and cost-effectiveness analyses are needed before broad clinical adoption.