An analysis of human equilibrative nucleoside transporter-1, ribonucleoside reductase subunit M1, ribonucleoside reductase subunit M2, and excision repair cross-complementing gene-1 expression in patients with resected pancreas adenocarcinoma: Implications for adjuvant treatment

Background: Tumor overexpression of excision repair cross-complementing gene-1 (ERCC1) may be associated with decreased survival in patients with pancreas adenocarcinoma (PAC). Human equilibrative nucleoside transporter-1 (hENT1) and ribonucleoside reductase subunits M1 and M2 (RRM1 and RRM2) are integral to cellular transport and DNA synthesis and are implicated as poor prognostic factors in other malignancies. To the authors's knowledge, their role in PAC is not defined. Methods: A prospective database was used to randomly select 95 patients who underwent pancreaticoduodenectomy for PAC between January 2000 and October 2008. Immunohistochemical analysis was performed on tumor samples for hENT1, RRM1 and RRM2, and ERCC1. Main outcomes were recurrence-free survival (RFS) and overall survival (OS). Results: The median follow-up, RFS, and OS were 49 months, 10.6 months, and 15.5 months, respectively. The median tumor size was 3 cm. Approximately 26% of patients had positive microscopic margins, 61% had lymph node involvement, and 88% and 45% had perineural and lymphovascular invasion, respectively. High tumor expression of hENT1, RRM1, RRM2, and ERCC1 was present in 85%, 40%, 17%, and 16%, respectively, of patients. High hENT1 expression was associated with reduced RFS (9.5 months vs 44.5 months; P =.029), but not with OS. RRM1 expression was not associated with survival. High RRM2 expression was associated with reduced RFS (6.9 months vs 16.0 months; P <.0001) and decreased OS (9.1 months vs 18.4 months; P <.0001). High ERCC1 expression was associated with reduced RFS (6.1 months vs 15 months; P =.04) and decreased OS (8.9 months vs 18.1 months; P =.03). After accounting for known adverse tumor factors, high expression of RRM2 and ERCC1 persisted as negative prognostic factors for RFS and OS. A subset analysis of patients who received adjuvant therapy (n = 74) revealed the same negative effect of high RRM2 and ERCC1 expression on RFS and OS. Conclusions: High tumor expression of RRM2 and ERCC1 are associated with reduced RFS and OS after resection of pancreas cancer. These biomarkers may help to personalize adjuvant therapy.