10-year survival for women with breast cancer and a PALB2 mutation was 48·0% (95% CI 36·5-63·2), compared with 74·7% (73·5-75·8) for patients with breast cancer without a mutation (adjusted hazard ratio for death 2·27, 95% CI 1·64-3·15; p<0·0001).
PALB2 is a recently identified breast cancer susceptibility gene whose protein is closely associated with BRCA2 and is essential for BRCA2 anchorage to nuclear structures.
PALB2 exons were amplified from 460 BRCA1/2-mutation negative women with familial breast and/or ovarian cancer and early-onset breast cancer using AmpliSeq technology and sequenced on an Ion Torrent PGM sequencer.
After exclusion of BRCA1, BRCA2, and syndromic breast cancer genes (CDH1, PTEN, and TP53), observed pathogenic variants in 5 of 16 genes were associated with high or moderately increased risks of breast cancer: ATM (OR, 2.78; 95% CI, 2.22-3.62), BARD1 (OR, 2.16; 95% CI, 1.31-3.63), CHEK2 (OR, 1.48; 95% CI, 1.31-1.67), PALB2 (OR, 7.46; 95% CI, 5.12-11.19), and RAD51D (OR, 3.07; 95% CI, 1.21-7.88).
Although an association between protein-truncating variants and breast cancer risk has been established for 11 genes, only alterations in BRCA1, BRCA2, TP53 and PALB2 have been reported in Asian populations.
Although inherited breast cancer has been associated with germline mutations in genes that are functionally involved in the DNA homologous recombination repair (HRR) pathway, including BRCA1, BRCA2, TP53, ATM, BRIP1, CHEK2 and PALB2, about 70% of breast cancer heritability remains unexplained.