CHEK2-related breast cancer: real-world challenges

Management of cancer risks associated with the CHEK2 gene, a moderate penetrance breast cancer gene, is challenging in real-world practice. Family history, traditional breast cancer risk factors, and specific genetic CHEK2 variants are risk modifiers in this setting and add complexity for surveillance and risk-reduction decisions. Here, we present a case series of Brazilian CHEK2 carriers affected by breast cancer.

Patients evaluated in the Oncogenetics Department of Hospital Sírio-Libanês (Brasília, Brazil) between November 2017 and September 2021, who had a personal history of breast cancer and a germline genetic test with a pathogenic or likely pathogenic CHEK2 variant, were selected for case description. Clinical pearls and knowledge gaps were highlighted for each case.

Twelve women were included in this descriptive analysis. All patients had early-stage breast cancer. Most of them were diagnosed with breast cancer prior to age 50 (9/12) and had a close relative affected by breast cancer (9/12). Seven patients harbored intronic pathogenic variants. Clinical pearls included the following: lack of risk estimates for intronic CHEK2 variants among non-European ancestry CHEK2 carriers, environmental exposures as a risk modifier, notable non-breast cancer diagnosis at young ages, incidental germline finding during tumor profiling, breast cancer diagnosis before the recommended age of breast cancer screening, family history of breast cancer as a risk modifier, and clinical outcomes after breast cancer treatment.

Improvements in cancer risk assessment and cancer prevention for CHEK2 carriers are still needed to overcome current clinical challenges on the management of these patients.