Philadelphia University + Thomas Jefferson University

Bussard Laboratory

Osteoblasts exchange exosomes (red) with metastasis-suppressed breast cancer cells (green)


Breast cancer preferentially metastasizes or migrates to the bones, where the five-year relative survival rate is less than 10%.  Metastatic lesions are thought to originate from disseminated tumor cells (DTCs) shed from a primary tumor.  Clinical evidence suggests that, upon entry in a secondary niche, DTCs undergo proliferative quiescence for a period of up to 25 years, where they are capable of escaping immune surveillance and evading chemotherapeutic agents which target cycling cells.  As a result, breast cancer patients successfully treated for primary breast cancer decades before suddenly develop overt macrometastases without prior symptoms.  This latency period before relapse at a secondary site can be defined as metastasis dormancy.  Thus, there is a critical need for elucidating the molecular mechanisms facilitating breast cancer dormancy and reactivation in the bone such that preventative therapeutics can be developed.  Despite the high prevalence of dormant tumors in humans, this area of cancer research is poorly understood and understudied.  The Bussard laboratory studies how specific interactions between normal bone osteoblasts andbreast cancer cells facilitate and maintain breast cancer cell dormancy in bone. 



Karen Bussard, MS, PhD
Assistant Professor

Contact Dr. Bussard




233 South 10th Street
Bluemle Life Sciences Building
Room 624A
Philadelphia, PA 19107

(215) 503-4511