The pattern of somatic mutations and chromosomal copy number variations (CNV) in young breast cancer (BC) patients (pts).

Abstract

579 Background: Young age at diagnosis is associated with poor prognosis, different distribution of BC subtypes and unique gene expression patterns. Yet, it is unknown whether young pts have different prevalence of somatic mutations or CNV. Methods: This analysis was performed on The Cancer Genome Atlas dataset. We divided pts according to their age into; young ( < 45 years) and old ( ≥ 45 years). We evaluated the association between age as a continuous variable and number of somatic mutations, CNV (amplification, gain, or deletions) using the chi-square test. We examined the genes showing somatic mutations or CNV in young pts and compared it to older pts using t-test. Results: 959 (138 < 45y) and 788 (124 ≥ 45y) pts were included in the somatic mutation and CNV analyses, respectively. Young age at diagnosis was associated with less number of somatic mutations, mainly in ER- BC (r = 0.21, p = 0.002). Within young ER+ pts, mutations in PIK3CA (32.6%), GATA3 (16.8%) and TP53 (16.8%) were the most common wit...