Women of childbearing age experience an increased
breast cancer risk associated with a completed pregnancy. For younger women, this increase in
breast cancer risk is transient and within a decade after parturition a cross over effect results in an ultimate protective benefit. The post-partum peak of increased risk is greater in women with advanced maternal age. Further, their lifetime risk for developing
breast cancer remains elevated for many years, with the cross over to protection occurring decades later or not at all. Breast
cancers diagnosed during pregnancy and within a number of years post-partum are termed pregnancy-associated or
PABC. Contrary to popular belief,
PABC is not a
rare disease and could affect up to 40,000 women in 2009. The collision between pregnancy and
breast cancer puts women in a fear-invoking paradox of their own health, their pregnancy, and the outcomes for both. We propose two distinct subtypes of
PABC:
breast cancer diagnosed during pregnancy and
breast cancer diagnosed post-partum. This distinction is important because emerging epidemiologic data highlights worsened outcomes specific to post-partum cases. We reported that post-partum breast involution may be responsible for the increased metastatic potential of post-partum
PABC. Increased awareness and detection, rationally aggressive treatment, and enhanced understanding of the mechanisms are imperative steps toward improving the prognosis for
PABC. If we determine the mechanisms by which involution promotes
metastasis of
PABC, the post-partum period can be a window of opportunity for intervention strategies.