DNA Repair Capacity in Peripheral Blood Lymphocytes Predicts Efficacy of Platinum-based Chemotherapy in Patients with Gastric Cancer

Objective: To investigate the correlation between ERCC1 expression levels in tumor tissue and peripheralblood lymphocytes (PBL) from patients with gastric cancer and assess the relationship between PBL DNA repairrate (DRR) and the efficacy of platinum chemotherapy.
Methods: A total of 53 patients with gastric cancerreceiving surgery and 20 controls were studied. ERCC1 protein expression in tumour tissue and PBL weredetermined by immunohistochemical staining. The PBL DRRs of 47 advanced patients and 20 controls wereestimated by comet assay.
Results: The positive expression rates of ERCC1 were 67. 9%, 56. 6% and 10.0% intumour tissues, PBLs of gastric cancer patients, and PBLs of the control group. PBL ERCC1 expression correlatedwith that in tissue (χ2=15. 463, p=0.000). Pearson contingency coefficient=0.475). DRRs of cancer patients bytail length (TL) (Z=4. 662, p=0.000) and tail moment (TM) (Z=3. 827, p=0.000) were significantly lower thanthat of control group. When TL was applied as an indicator, the correlation between DRR and chemotherapyefficacy was significant (Spearman rank correlation r=0.327, p=0.032). Patients with low levels of DRR in PBLpresented better short-term efficacy of chemotherapy than those with high levels of DRR.
Conclusions: TheERCC1 expression in PBLs may indirectly reflect ERCC1 expression in gastric cancer tissues. Compared withnon-cancer populations, patients with gastric cancer may have lower DNA repair capacity. DRR in PBL maypredict the short-term efficacy of platinum-based chemotherapy for patients with advanced gastric cancer.