Breast cancer in young women: impact of pregnancy on biology and outcome

In this work, we found that proliferation-related prognostic gene signatures could aid treatment decision-making independent of age. This is clinically relevant for the younger breast cancer population given the potential long-term side effects of adjuvant systemic chemotherapy and hence the need to identify patients who are less likely to benefit adjuvant chemotherapy. In addition, it was clear that young age at diagnosis adds extra biological complexity, which is independent of differences in breast cancer subtype distribution. This includes enrichment with known breast cancer targets like RANKL. Whilst these results require further validation, either experimentally or in other clinical data sets, it suggests that separate therapeutic approaches may need to be specifically designed in order to improve outcomes for breast cancer arising in young women. In this regard, and based on our results and supportive evidence from other studies, we initiated a proof-of-concept prospective phase II neoadjuvant study investigating the role of denosumab, a RANKL inhibitor on modulating tumor biology in young premenopausal breast cancer patients. We found that diagnosis during pregnancy does not significantly influence the classic pathological features or the prevalence of breast cancer subtypes. We also did not find obvious differences in the distribution of PIK3CA mutations. However, we found that tumors diagnosed during pregnancy have activated serotonin receptor signaling and high expression of potential breast cancer targets; of particular interest IGF1, and PDL1. Such differences appeared to be reflected in the normal pregnant breast underscoring the potential role of the pregnant breast microenvironment on the tumor transcriptome. We were not able to associate these genes with prognosis, which could be partly due to lack of statistical power. Of note, we cannot confirm whether any of these aberrations are key drivers of the biology of tumors diagnosed during pregnancy.
Doctorat en Sciences biomédicales et pharmaceutiques
info:eu-repo/semantics/nonPublished