Timely referral of a patient for genetic counseling for breast cancer allows you to adjust treatment tactics and take preventive measures. A 29-year-old patient with breast cancer and a family history on her mother’s side was consulted. Given the absence of frequent pathogenic variants in the BRCA1 and BRCA2 genes, panel targeted sequencing was performed. According to the test results, a pathogenic variant C.844C>T (p.Arg282Trp) was identified in exon 8 of the TP53 gene in a heterozygous form associated with the development of Li-Fraumeni syndrome. Validation of the result was performed by Sanger sequencing.

Taking into account the hereditary nature of the disease, as well as the existing risk of developing primary multiple breast cancer, a surgical intervention was performed in the amount of a radical bilateral subcutaneous mastectomy with simultaneous reconstruction with endoprostheses and a biopsy of the sentinel lymph node on the left. Radiation therapy was not performed due to the high probability of radiation-induced cancer in this syndrome. Thus, the referral of the patient for genetic counseling and subsequent DNA diagnostics made it possible to adjust the treatment and take preventive measures.