Background and purpose: The role of the immune system in tumor response to chemo-radiotherapy (CRT) is an emerging issue. This work aimed at identifying predictive and prognostic immunogenetic variants in LARC patients after preoperative (po)-CRT and surgery.
Materials and methods: A set of 192 polymorphisms in 34 candidate genes involved in the regulation of the immune response signalling network, was selected and analyzed in 370 LARC patients treated with po-CRT and surgery, split into a Test Set (n = 233) and a Validation Set (n = 137). Immunogenetic markers were selected based on a concordant significant effect on 2-year relapse-free survival (2-yrRFS) (bootstrapped P < 0.05) in both patients Sets. The effect of the selected immunogenetic variants on 5-year metastases-free (5yrMFS), 5-year disease-free (5yrDFS), and 10-year overall (10yrOS) survival was tested in the entire Set of 370 patients.
Results: Two immunogenetic IL17F (IL17F-rs641701 and IL17F-rs9463772) markers predictive of 2yrRFS, 5yrDFS, 5yrMFS, and 10yrOS were identified. The combination of tumor regression grade (TRG) and patients genotype for IL17F-rs641701 and IL17F-rs9463772 allowed the identification of subgroups of patients with differential prognosis in term of both 5yrDFS (HR 11.29, P-value <0.001, and HR 5.86, P-value = 0.001, respectively) and 10yrOS (HR 7.07, P-value = 0.005, and HR 6.05, P-value = 0.002, respectively).
Conclusion: IL17F-rs641701 and IL17F-rs9463772 were highlighted as promising immunogenetic markers significantly associated with the prognosis of LARC patients. After a prospective validation of the herein reported findings, the combination of TRG and patients genotype should be considered to provide additional stratification criteria for the selection of a personalized multimodality treatment.
Keywords: Fluoropyrimidines; IL17F; Immunogenetics; Neo-adjuvant chemo-radiotherapy; Polymorphisms; Rectal cancer.
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