Refining Risk Stratification in Hepatocellular Carcinoma by Integrating Tertiary Lymphoid Structures and Microvascular Invasion: a Multicenter Retrospective Study.

Background: The pattern of tertiary lymphoid structures (TLS) differs from that of microvascular invasion (MVI) in patients with hepatocellular carcinoma (HCC). This multicenter study aimed to evaluate the prognostic value of integrating TLS and MVI and assess their interaction with adjuvant hepatic arterial infusion chemotherapy (aHAIC).

Methods: From January 2013 to December 2021, this study enrolled 923 HCC patients (cohort A: 437; cohort B: 275; cohort C: 211) who underwent curative resection and stratified them into different groups based on their TLS and MVI status. The cohort C (the aHAIC group vs. the control group) enrolled patients confirmed HCC with MVI+. Recurrence-free survival (RFS) and overall survival (OS) were evaluated. RNA-seq analysis was performed on 79 patients fresh-frozen tissues of the cohort C.

Results: The patients were divided into four subgroups based on TLS and MVI status: 21.05% TLS-/MVI-, 15.10% TLS-/MVI+, 46.91% TLS+/MVI-, and 16.93% TLS+/MVI+ in the cohort A, and 25.82% TLS-/MVI-, 11.27% TLS-/MVI+, 47.27% TLS+/MVI-, and 15.64% TLS+/MVI+ in the cohort B. Patients in the TLS+/MVI- group exhibited the best prognosis, while those in the TLS-/MVI+ group had the worst prognosis. The outcomes for the TLS-/MVI- and TLS+/MVI+ patients were comparable (RFS: p = 0.528, 0.354; OS: p = 0.931, 0.805, respectively for the A and B cohorts). In the cohort C, TLS+ patients had better RFS than TLS- patients both in the control (TLS+ vs TLS-: 19.57 [95% CI: 13.17, NA] vs 8.53 [95% CI: 5.33, 13.33] months) and adjuvant HAIC groups (TLS+ vs TLS-: NA vs 14.80 [95% CI: 10.30, NA] months). RFS was improved, however, no significant difference in OS was observed between TLS- and TLS+ groups in the cohort C. RNA-seq data analysis revealed that the differentially expressed genes between TLS+ and TLS- were predominantly associated with T-cell-inflamed tumor microenvironment and anti-tumor immune response.

Conclusion: Our findings establish TLS as a complementary biomarker to MVI, refining postoperative risk stratification. TLS status further stratifies MVI+ patients for HAIC responsiveness, identifying those more likely to benefit from adjuvant HAIC, highlighting its potential to guide personalized therapeutic strategies.