Inhibition of tumors cell growth in osteosarcoma-bearing SD rats through a combination of conventional and metronomic scheduling of neoadjuvant chemotherapy.

Aim: To investigate whether a combination of conventional and metronomic scheduling of chemotherapy could enhance and extend the effectiveness of chemotherapy against osteosarcoma.

Methods: A total of 110 osteosarcoma-bearing SD rats were randomly divided into four groups, three of which were given conventional, metronomic or combination scheduling of chemotherapy, and the remaining one served as a control. Tumor volumes were measured every week during the treatment period of 8 weeks. At the end of treatment, tumors were removed from the rats and weighed. Expression of VEGFA in tumors was determined using Western blot assays.

Results: As indicated by the tumor volume, conventional and metronomic schedules showed similar trends in tumor growth curves, and both of them lost their inhibitory effect in the sixth week, whereas the combination schedule maintained effectiveness until the end of treatment. Statistical significance with tumor volumes and weights was found among the groups (P<0.001), with combination scheduling being the most effective (P<0.001). Western blot indicated that all the therapy groups had significantly decreased expression of VEGFA (P<0.01), and the combination scheduling group had the lowest VEGFA expression.

Conclusion: Combination of conventional and metronomic scheduling of chemotherapy could be a promising treatment for osteosarcoma. Antiangiogenesis contributed to the effect of combination scheduling.