Progranulin (GP88) tumor tissue expression is associated with increased risk of recurrence in breast cancer patients diagnosed with estrogen receptor positive invasive ductal carcinoma
1 A&G Pharmaceutical Inc., 9130 Red Branch Rd., Columbia, MD 21045, USA
2 Department of Statistics, University of Minnesota, 224 Church St SE, Minneapolis, MN 55455, USA
3 Department of Pathology, University of Maryland, Greenebaum Cancer Center, 22 S Greene St., Baltimore, MD 21201, USA
4 Jackson Memorial Hospital, University of Miami, 1611 NW 12th Av., Miami, FL 33136, USA
5 EEH Breast Cancer Research and Treatment Center, 17050 Medical Center Drive, Baton Rouge, LA 70816, USA
6 Department of Medicine, University of Maryland, Greenebaum Cancer Center, 22 S Greene St., Baltimore, MD 21201, USA
7 Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160, USA
8 Fox Chase Cancer Center, 333 Cottman Ave., Philadelphia, PA 19111, USA
Breast Cancer Research 2012, 14:R26 doi:10.1186/bcr3111Published: 8 February 2012
GP88 (progranulin) has been implicated in tumorigenesis and resistance to anti-estrogen therapies for estrogen receptor positive (ER+) breast cancer. Previous pathological studies showed that GP88 is expressed in invasive ductal carcinoma (IDC), but not in normal mammary epithelial tissue, benign lesions or lobular carcinoma. Based on these results, the present study examines GP88 prognostic significance in association with recurrence and death risks for ER+ IDC patients.
Two retrospective multi-site clinical studies examined GP88 expression by immunohistochemistry (IHC) analysis of paraffin-embedded breast tumor tissue sections from ER+ IDC patients (lymph node positive and negative, stage 1 to 3) in correlation with patients' survival outcomes. The training study established a GP88 cut-off value associated with decreased disease-free (DFS) and overall (OS) survivals. The validation study verified the GP88 cut-off value and compared GP88 prognostic information with other prognostic factors, particularly tumor size, grade, disease stage and lymph node status in multivariate analysis.
GP88 expression is associated with a statistically significant increase in recurrence risk for ER+ IDC patients. The training study established that GP88 3+ score was associated with decreased DFS (P = 0.0004) and OS (P = 0.0036). The independent validation study verified that GP88 3+ score was associated with a 5.9-fold higher hazard of disease recurrence and a 2.5-fold higher mortality hazard compared to patients with tumor GP88 < 3+. GP88 remained an independent risk predictor after considering age, ethnicity, nodal status, tumor size, tumor grade, disease stage, progesterone receptor expression and treatments.
The survival factor GP88 is a novel prognostic biomarker, predictive of recurrence risk and increased mortality for non-metastatic ER+ IDC patients. Of importance, our data show that GP88 continues to be a prognostic factor even after five years. These results also provide evidence that GP88 provides prognostic information independent of tumor and clinical characteristics and would support prospective study to examine whether GP88 expression could help stratify patients with ER+ tumors for adjuvant therapy.