Through a recent study of over 12,000 Polish women with breast cancer, PALB2 mutations were detected in almost 1%. In this study, about one third of those with a PALB2 mutation had triple negative (lacking estrogen, progesterone and HER2 receptors) breast cancer and the average age at breast cancer diagnosis was 53.3 years. Breast tumors of 2 cm or larger had substantially worse outcomes (i.e., 32.4% 10-year survival) compared with tumors smaller than 2 cm (i.e., 82.4% 10-year survival).
Overall, the study findings confirm a substantially elevated risk of breast cancer (24-40%) among women with a PALB2 mutation up to age 75. The five-year cumulative incidence of contralateral breast cancer was 10% among those with a PALB2 mutation, compared to 17% among those with a BRCA1 mutation and 3% among those without a mutation in either gene. Survival at 10 years was also worse in women with a PALB2 mutation at just under 50%, compared to 72.0% among those with a BRCA1 mutation, and 74.7% among those without a mutation in either gene.
Given a possible association of poorer outcomes among women with breast cancers larger than 2 cm, focused efforts should be made to detect small cancers among women with a PALB2 mutation through various screening procedures. Furthermore, as early data suggests women with PALB2-associated breast cancer may develop more aggressive disease, it is important to study breast cancer characteristics and outcomes in PALB2 carriers through larger studies.
Ultimately, personalized treatments may be important for these women, thus it is vital to collect details about pathological features (receptor status), treatment (including chemotherapy regimen) and follow-up. Only through these types of research efforts will we be able to learn more about this important gene and figure out how to better care for those with mutations. As outlined on the last page of this newsletter, we are currently recruiting 500 PALB2 mutation carriers to determine breast cancer characteristics and outcomes.
Cybulski C,et al. Clinical outcomes in women with breast cancer and a PALB2 mutation: a prospective cohort analysis. Lancet Oncol. 2015 Jun;16(6):638-44. PMID: 25959805.