CHEK2-mutatie in Nederlandse borstkankerfamilies

• In the majority of breast cancer families, DNA testing does not show BRCA1 or BRCA2 mutations and the genetic cause of breast cancer remains unexplained.
• Routine testing for the CHEK2*1100delC mutation has recently been introduced in breast cancer families in the Netherlands.
• The 1100delC mutation in the CHEK2-gene may explain the occurrence of breast cancer in about 5% of non-BRCA1/2 families in the Netherlands.
• In the general population the CHEK2*1100delC mutation confers a slightly increased breast cancer risk, but in a familial breast cancer setting this risk is between 35-55% for first degree female carriers.
• Female breast cancer patients with the CHEK2*1100delC mutation are at increased risk of contralateral breast cancer and may have a less favourable prognosis.
• Female heterozygous CHEK2*1100delC mutation carriers are offered annual mammography and specialist breast surveillance between the ages of 35-60 years.
• Prospective research in CHEK2-positive families is essential in order to develop more specific treatment and screening strategies.

Conflict of interest and financial support: none declared.