These findings suggest that the Brazilian founder mutation p.R337H, the most frequent germline TP53 mutation reported to date, is not a common germline alteration in Portuguese women diagnosed with BC.
Although 75% of carriers of these mutations showed significant HER2 overexpression (3+), corroborating previous studies, only 22.7% of p.R337H patients had BC overexpressing HER2.
The prevalence of p.R337H was higher in women diagnosed with BC at or before age 45 (12.1%, CI95%: 9.1%-15.8%) than at age 55 or older (5.1%, CI95%: 3.2%-7.7%), p<0.001).
R337H has been identified in Brazilian families with Li-Fraumeni or related syndromes predisposing to cancers in childhood (ie, brain, renal, and adrenocortical carcinomas), adolescence (ie, soft tissue and bone sarcomas), and young adulthood (ie, breast cancer).
These results demonstrate that the R337H mutation can significantly increase the risk of breast cancer in carriers, which likely depends on additional cooperating genetic factors.
Here we have assessed the prevalence of R337H in 750 healthy women participating in a community-based breast cancer screening program in the area of Porto Alegre.
Families with the R337H mutation presented a wide spectrum of tumours, including breast cancers (30.4%), brain cancers (10.7%), soft tissue sarcomas (10.7%) and adrenocortical carcinomas (8.9%).