Research Article| Volume 49, ISSUE 8, P1993-1999, May 2013

Excess breast cancer risk in first degree relatives of CHEK2∗1100delC positive familial breast cancer cases

Published:February 18, 2013DOI:



      The CHEK2∗1100delC mutation confers a relative risk of two for breast cancer (BC) in the general population. This study aims to explore the excess cancer risk due to the CHEK2∗1100delC mutation within a familial non-BRCA1/2 breast cancer setting.

      Patients and Methods

      Cancer incidences were compared between first degree relatives of 107 familial breast cancer patients positive for the CHEK2∗1100delC mutation (CHEK2 positive families) and first degree relatives of 314 familial breast cancer patients without the CHEK2∗1100delC mutation (CHEK2 negative families). All families were derived from the same pool of familial non-BRCA1/2 breast cancer families (n = 2554). Medical information of 2188 first degree relatives of these families was analysed for cancer risk. CHEK2∗1100delC status of relatives was unknown.


      Increased breast cancer risk (hazard ratio (HR) 2.0 (95% confidence interval (CI): 1.4–2.7), p < 0.001) was observed in sisters of CHEK2∗1100delC positive index cases compared to sisters of CHEK2∗1100delC negative index cases. HR was 1.6 (95% CI: 1.0–2.4) for mothers of CHEK2 positive versus negative index cases (p = 0.041). For second primary breast cancers HR was increased in CHEK2∗1100delC positive index cases (HR 2.1, 95% CI: 1.3–3.3, p = 0.003) and their sisters (HR 2.6, 95% CI: 1.1–6.1, p = 0.025).


      There is an excess breast cancer risk in first degree relatives of CHEK2∗1100delC positive non-BRCA1/2 familial breast cancer patients compared to non-CHEK2∗1100delC familial breast cancer relatives.
      Genotyping for the CHEK2∗1100delC mutation in a familial breast cancer setting contributes to optimal clinical surveillance in countries in which this mutation is prevalent. Carriers and female relatives are eligible for stringent breast surveillance programs.


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