Breast tumor stroma: A driving force in the development of resistance to therapies

Breast cancer is the most common cancer and the second leading cause of cancerrelated death in women worldwide. In spite of huge advancements in early detection
and ever-increasing knowledge of breast cancer biology, approximately 30% of patients with early-stage breast cancer experience disease recurrence. Most patients are
chemosensitive and cancer free immediately after the treatment. About 50% to 70%
of breast cancer patients, however, will relapse within 1 year. Such a relapse is usually concomitant with adenocarcinoma cells acquiring a chemoresistant phenotype.
Both de novo and acquired chemoresistance are poorly understood and present a
major burden in the treatment of breast cancer. Although, previously, chemoresistance was largely linked to genetic alterations within the cancer cells, recent investigations are indicating that chemoresistance can also be associated with the tumor
microenvironment. Nowadays, it is widely believed that tumor microenvironment is
a key player in tumor progression and response to treatment. In this study, we will
review the interactions of breast tumor cells with their microenvironment, present the
latest research on the resistance mediated by the stromal component in breast cancer,
and discuss the potential therapeutic strategies that can be exploited to treat breast
cancers by targeting tumor microenvironment