Breast cancer is the most common malignant disease among females worldwide and the
leading cause of cancer related death. Especially during pregnancy, the incidence
of breast cancer is on a continuous rise. Additionally, pregnancy-associated breast
cancer is linked to a poor prognosis. It has been hypothesized that pregnancy related
changes in the breast might delay a timely diagnosis. Further, hormonal changes and
adaptational processes of the maternal immune systeme might simultaneously promote
a tolerogenic microenvironment for the tumor. Therefore, we established a preclinical
model that provides a prerequisite to comprehensively investigate the impact of the
study maternal immune adaptations to pregnancy in modulating the severity of breast
cancer during pregnancy.
Data available from our preclinical model revealed a significantly advanced tumor
progression in pregnant mice, compared to non-pregnant controls upon inoculation of
the murine breast cancer tumor cell lines Py8119 or E0771. Tumor progression was determined
by caliper-based calculation of tumor volume, which was independently confirmed by
end-of-experiment tumor volume assessment using CT scans. Mortality rates were similar
between mouse groups, and confounding factors leading to mortality criteria, such
as food and water consumption, could be excluded. Plug-to-pregnancy rate remained
similar between tumor and non-tumor bearing pregnant mice, as well as serum progesterone
levels. Litter size and fetal as well as neonatal weight remained unaffected between
litters born by control or tumor-bearing females.
We further aim to initiate a multi-center longitudinal cohort study entitled PRINCEbreast,
based in Hamburg, in which women diagnosed with breast cancer during pregnancy shall
be recruited.
