Published October 3, 2016 | Version v1
Journal article Open

Patient survival and tumor characteristics associated with CHEK2:p.I157T – findings from the Breast Cancer Association Consortium

  • 1. Department of Obstetrics and Gynecology, University of Helsinki and Helsinki University Hospital, P.O. Box 700, 00029, HUS, Helsinki, Finland
  • 2. Department of Oncology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
  • 3. Gynaecology Research Unit, Hannover Medical School, Hannover, Germany
  • 4. Department of Genetics and Pathology, Pomeranian Medical University, Szczecin, Poland
  • 5. Department of Pathology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
  • 6. Unit of Systems Toxicology, Finnish Institute of Occupational Health, Helsinki, Finland
  • 7. Department of Clinical Genetics, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
  • 8. Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
  • 9. Centre for Cancer Genetic Epidemiology, Department of Oncology, University of Cambridge, Cambridge, UK
  • 10. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
  • 11. Division of Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
  • 12. Department of Laboratory Medicine and Pathology Mayo Clinic, Rochester, MN, USA
  • 13. Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA
  • 14. Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, USA
  • 15. Department of Gynaecology and Obstetrics, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
  • 16. Human Genetics Division, Genome Institute of Singapore, Singapore, Singapore
  • 17. Lunenfeld-Tanenbaum Research Institute of Mount Sinai Hospital, Toronto, ON, Canada
  • 18. Laboratory of Cancer Genetics and Tumor Biology, Northern Finland Laboratory Centre NordLab, Oulu, Finland
  • 19. Cancer Center, Kuopio University Hospital, Kuopio, Finland
  • 20. Department of Oncology - Pathology, Karolinska Institutet, Stockholm, Sweden
  • 21. Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK
  • 22. Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands

Description

Background: P.I157T is a CHEK2 missense mutation associated with a modest increase in breast cancer risk. Previously, another CHEK2 mutation, the protein truncating c.1100delC has been associated with poor prognosis of breast cancer patients. Here, we have investigated patient survival and characteristics of breast tumors of germ line p.I157T carriers.

Methods: We included in the analyses 26,801 European female breast cancer patients from 15 studies participating in the Breast Cancer Association Consortium. We analyzed the association between p.I157T and the clinico-pathological breast cancer characteristics by comparing the p.I157T carrier tumors to non-carrier and c.1100delC carrier tumors. Similarly, we investigated the p.I157T associated risk of early death, breast cancer-associated death, distant metastasis, locoregional relapse and second breast cancer using Cox proportional hazards models.

Additionally, we explored the p.I157T-associated genomic gene expression profile using data from breast tumors of 183 Finnish female breast cancer patients (ten p.I157T carriers) (GEO: GSE24450). Differential gene expression analysis was performed using a moderated t test. Functional enrichment was investigated using the DAVID functional annotation tool and gene set enrichment analysis (GSEA). The tumors were classified into molecular subtypes according to the St Gallen 2013 criteria and the PAM50 gene expression signature.

Results: P.I157T was not associated with increased risk of early death, breast cancer-associated death or distant metastasis relapse, and there was a significant difference in prognosis associated with the two CHEK2 mutations, p.I157T and c.1100delC. Furthermore, p.I157T was associated with lobular histological type and clinico-pathological markers of good prognosis, such as ER and PR expression, low TP53 expression and low grade. Gene expression analysis suggested luminal A to be the most common subtype for p.I157T carriers and CDH1 (cadherin 1) target genes to be significantly enriched among genes, whose expression differed between p.I157T and non-carrier tumors.

Conclusions: Our analyses suggest that there are fundamental differences in breast tumors of CHEK2:p.I157T and c.1100delC carriers. The poor prognosis associated with c.1100delC cannot be generalized to other CHEK2 mutations.

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Additional details

Funding

COGS – Collaborative Oncological Gene-environment Study 223175
European Commission