TP53 and breast cancer: Li-Fraumeni syndrome accounts for about 1% of hereditary breast cancers.55 Age at tumor onset is earlier: the risk of developing cancer by age 40 years is 50% and as high as 90% by age 60.56 In 24 families with Li-Fraumeni syndrome, the incidence of breast cancer was 22.5% (45/200), age at onset was younger than 45 years in 77% of women, the proportion of bilateral breast cancer was 5%, and 11% of breast cancer cases were associated with other tumors.57 In China, Cao et al58 found that the frequency of disease-associated TP53 germline mutations was 0.8% (1/240).