Abstract:
Background:
Breast cancer incidence and mortality vary significant
ly among different nations and racial groups. African
nations have the highest breast cancer mortality rates in the world, even though the incidence rates are below those of
many nations. Differences in disease progression suggest th
at aggressive breast tumors may harbor a unique molecular
signature to promote disease progression. However, few studies have investigated the pathology and clinical markers
expressed in breast tissue from regional African patient populations.
Methods:
We collected 68 malignant and 89 non-cancerous samples from Kenyan breast tissue. To characterize the
tumors from these patients, we constructed tissue microarrays (TMAs) from these tissues. Sections from these TMAs
were stained and analyzed using immunohistochemistry to detect clinical breast cancer markers, including estrogen
receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 receptor (HER2) status, Ki67, and immune
cell markers.
Results:
Thirty-three percent of the tumors were triple negative (ER-, PR-, HER2-), 59 % were ER+, and almost all tumors
analyzed were HER2-. Seven percent of the breast cancer patients were male, and 30 % were <40 years old at diagnosis.
Cancer tissue had increased immune cell infiltration with recruitment of CD163+ (M2 macrophage), CD25+ (regulatory
T lymphocyte), and CD4+ (T helper) cells compared to non-cancer tissue.
Conclusions:
We identified clinical biomarkers that may assist i
n identifying therapy strategies for breast cancer
patients in western Kenya. Estrogen receptor status in particular should lead initial treatment strategies in these
breast cancer patients. Increased CD25 expression suggests a need for additional treatment strategies designed to
overcome immune suppression by CD25+ cells in order to promote the antitumor activity of CD8+ cytotoxic T cells.
