Abstract
We report the case of a breast cancer survivor, diagnosed with an underlying CHEK2 c.1100delC heterozygosity, who developed a papillary thyroid cancer 5 years later. A CHEK2 c.1100delC (likely) pathogenic variant is associated with an increased risk of breast, prostate and colorectal cancer and therefore risk-specific screening will be offered. Current national and international screening guidelines do not recommend routine screening for thyroid cancer. Hence, we reviewed the literature to explore the possible association between a CHEK2 mutation and thyroid cancer. A weak association was found between the various CHEK2 mutations and papillary thyroid cancer. The evidence for an association with CHEK2 c.1100delC in particular is the least robust. In conclusion, there is insufficient evidence to warrant systematic thyroid screening in CHEK2 carriers.