title: Monitoring serum HER2 levels in breast cancer patients.
abstract: BACKGROUND
  We have developed a new approach to reduce the serum interference for ELISA. The purpose of this study is to investigate if we can use the optimized ELISA (MBB-ELISA) to detect serum soluble HER2/neu (sHER2) in early stage primary breast cancer and monitor its change during treatments.
  
  
  RESULTS
  We collected sera preoperatively from 118 primary breast cancer patients. Serum samples were also collected sequentially from a subset of patients during and after adjuvant treatment. sHER2 in these samples was measured by the MBB-ELISA. Only 16.7 % of tissue HER2 (tHER2) positive patients had significantly elevated sHER2 levels in serum. Interestingly, sera of some patients with tHER2 negative tumors, including those that were 2+ by IHC but negative by FISH, demonstrated slightly elevated sHER2 levels. Multivariate analysis demonstrated that patients with elevated sHER2 (> = 7 ng/ml) had significantly worse disease free survival. During treatments, sHER2 levels consistently fell in response to adjuvant therapies. Nevertheless, in all 4 patients who developed metastases, a steady rise in sHER2 levels was noted before metastatic disease became clinically evident.
  
  
  CONCLUSIONS
  For early stage breast cancers, sHER2 is a poor biomarker to predict tHER2 status, but may have value to supplement tissue tests to identify patients with HER2 tumors. Our results also suggest that sHER2 is worth further study as a biomarker to monitor breast cancer patients during treatments.
authors.affiliation: Division of Endocrine and Oncologic Surgery, Rena Rowan Breast Center, Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 USA.
authors.forename: Julia
authors.initials: J
authors.lastname: Tchou
authors.affiliation: Department of Pathology and Lab Medicine, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104 USA.
authors.forename: Lian
authors.initials: L
authors.lastname: Lam
authors.affiliation: Medical Scientist Training Program; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA ; The Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA USA.
authors.forename: Yun Rose
authors.initials: YR
authors.lastname: Li
authors.affiliation: Division of Endocrine and Oncologic Surgery, Rena Rowan Breast Center, Abramson Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 USA.
authors.forename: Claire
authors.initials: C
authors.lastname: Edwards
authors.affiliation: Division of Cardiovascular Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 USA.
authors.forename: Bonnie
authors.initials: B
authors.lastname: Ky
authors.affiliation: Department of Pathology and Lab Medicine, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104 USA.
authors.forename: Hongtao
authors.identifier: 0000-0001-9173-0049
authors.initials: H
authors.lastname: Zhang
keywords: Biomarker; Breast cancer; HER2/neu; MBB buffer; SHER2