Impact of germline CHEK2 mutations on biochemical relapse free survival and metastasis free survival after radical treatment for patients with prostate cancer

Objective: to evaluate the prognostic value of pathogenic germline BRCA1, BRCA2 and CHEK2 mutations on biochemical relapse-free survival (BRFS) and metastasis-free survival (MFS) following radical treatment in patients with localized and locally advanced prostate cancer (PCa).Materials and methods. Tumor features and outcomes of 102 patients with PCa were analyzed. In all patients nadir prostate-specific antigen (PSA) have been achieved: radical prostatectomy was undergone by 85 patients; 17 patients received radical radiotherapy. Exclusion criteria were postoperative nadir PSA >0.2 ng/mL, adjuvant hormone therapy. During follow-up a total of 65 (63.7 %) patients developed biochemical relapse (BCR), and 39 (38.2 %) patients developed metastatic progression of PCa. All patients were genotyped for clinically significant pathogenic germline mutations 1100delC, I157Tand IVS2+1G>A in the CHEK2gene, 185delAG, 4153delA, 5382insC, 3875del4, 3819del5, C61G, 2080delA in the BRCA1 gene, 6174delT in the BRCA2 gene by polymerase chain reaction real-time using a set “OncoGenetics” (LLC “Research and Production Company DNA-Technology”, Russia, registration certificate № 2010/08415). The second step was the determination of the coding part of the BRCA1 and BRCA2 genes by the Sanger sequencing using a set “Beckman Coulter enomeLab GeXP”.Results. Pathogenic germline mutations in the CHEK2 gene were identified in 16 (15.7 %) patients: heterozygous missense mutation I157T (c.470T>C, rs17879961) was identified in 15 (14.7 %) patients, heterozygous mutation IVS2+1G>A (c.319+1G>A, rs765080766) was identified in 1 (0.9 %) patient. No cases of the 1100delC mutation in the CHEK2 gene and clinically significant mutations in the BRCA1 and BRCA2 genes were detected. Germline mutations I157TandIVS2+1G>A in the CHEK2gene are statistically significant independent unfavorable prognostic factor for BRFS (hazard ratio (HR) 3.272; 95 % confidence interval (CI) 1.688—6.341, p <0.001) and marginally significant independent unfavorable prognostic factor for MFS (HR 2.186; 95 % CI 0.932—5.126, p = 0.072). Subgroup analysis confirm independent prognostic value of germline CHEK2 mutations in patients with localized PCa (for BRFS HR 3.048; 95 % CI 1.024—9.078; p = 0.045; for MFS HR 5.168; 95 % CI 1.231—21.699; p = 0,025), and its marginally significant prognostic value in patient with locally advanced PCa T3-T4N0M0 (for BRFS HR 3.099; 95 % CI 0.991-9.689; р = 0.052) and TanyN1M0 stage (for MFS HR 5.089; 95 % CI 0.724-35.755; p = 0.102). Germline mutations I157T and IVS2+1G>A in the CHEK2 gene are associated with increased risk of early BCR during 12 months (HR 3.795; 95 % CI 2.06-6.98; p <0.001) and early metastatic progression during 24 months (HR 6.72; 95 % CI 2.02-22.34; p = 0.004) following radical treatment. This study has certain limitations due to its retrospective recruitment and a small sample of patients. Conclusions. Our results confirm that germline CHEK2 mutations I157T and IVS2+1G>A are an unfavorable prognostic factor for patients with PCa, associated with increased risk of early biochemical relapse and metastatic progression, worse BRFS and MFS