Distraction-suppression effect on osteosarcoma.

Osteosarcoma is the most common primary malignant bone tumor. It occurs mainly in children and adolescents. In patients with open growth plate, epiphyseal distraction is used to separate the uninvolved epiphysis from adjacent tumor. This helps preserve the growth potential and restore joint and limb function to a great extent. Interestingly, epiphyseal distraction also appears to inhibit the proliferation of osteosarcoma tumor cells and to increase sensitivity to chemotherapy. Tumor interstitial pressure (TIP) is often elevated in the microenvironment of most solid tumors, including osteosarcoma. Elevated TIP can promote the proliferation, invasion, and migration ability of osteosarcoma cells and also decrease the uptake and distribution of chemotherapeutic agents. Studies have confirmed that the sustained volumetric strain produced in distracted tissue decreases TIP; it stretches extracellular matrix, decreases interstitial density, and increases vessel diameter. We hypothesize that lowering of TIP during the period of epiphyseal distraction inhibits the proliferation and invasion of osteosarcoma cell and, at the same time, increases blood perfusion in the tumor and thus enhances uptake and distribution of chemotherapy agents. If the hypothesis is proved to be true, distraction of tumor segment could be a novel supplementary treatment for osteosarcoma by manipulation of TIP.