Clinical significance of tertiary lymphoid structure maturity in colorectal cancer patients.

Objectives: To explore the clinical significance of the maturation of tertiary lymphoid structures (TLS) in colorectal cancer patients.

Methods: A total of 230 surgical removed colorectal cancer specimens with detailed follow-up data were collected from Yinzhou Second Hospital. There were 128 cases of mature TLS and 108 cases of immature TLS according to immunohistochemical results. The patient age, gender, maximum tumor diameter, tumor location, differentiation degree, depth of invasion, lymph node metastasis, vascular tumor thrombus, liver metastasis, distant non-liver metastasis, mismatch repair status, expression of Ki-67, P53 and programmed cell death ligand 1 (PD-L1) were analyzed. The Kaplan-Meier method (Breslow test) was used to analyze the survival of patients, and multivariate Cox regression model was applied to analyze the prognostic factors.

Results: Compared to the immature TLS group, the mature TLS group showed a significantly lower rate of vascular tumor thrombus, lymph node metastasis, and liver metastasis. Additionally, the positive expression rate of Ki-67 was markedly reduced, while the rate of deficient mismatch repair and the positive expression rate of PD-L1 were significantly increased (all <0.05). The overall survival rate of the mature TLS group was superior to that of the immature TLS group (Breslow=4.553, <0.05). Cox regression analysis indicated that lymph node metastasis was an independent risk factor for the prognosis of colorectal cancer patients (<0.01), while TLS maturation was a protective factor (<0.05).

Conclusions: The formation of TLS may play a significant role in inhibiting lymph node metastasis, liver metastasis, and vascular tumor thrombus in colorectal cancer, and patients with mature TLS have a favorable clinical prognosis, which can provide a reference for the immunotherapy and prognostic assessment of colorectal cancer patients.