[Evaluation of necrosis caused by preoperative chemotherapy in 9 cases of classic central osteosarcoma]

The authors describe 9 cases of classic osteosarcoma treated with preoperative chemotherapy according to the current schemes and consecutively treated by surgery. All the patients were between 12 and 17 years old. They initially had a needle biopsy or open biopsy to confirm the diagnosis. After 2 cycles of chemotherapy they were treated by limb salvage procedure in 7 cases and by ablative surgery in 2 cases. The surgical specimens were very accurately examined both macroscopically and histologically to evaluate the effects of preoperative chemotherapy. For this reasons the quantity of the tumoral necrosis, that represents the reaction of the tumor to the therapy, was researched and mapped. The intention was to decide whether or not to use the same pharmacological treatment after the surgical therapy. These evaluation criteria do not only have the objective of locally keeping under control the disease, but mostly to oppose micrometastasis. In fact they are almost always present at the beginning of the symptomatology but are not diagnosed with the usual exams. The sites of viable tumor after treatment are: soft tissues around the bone, areas in contact with cartilage and subcortical areas. In 6 cases out of 9 we found macroscopically a fibrous pseudo-capsule around all the tumoral area. The follow-up of the nine cases varies from six to fifty-two months and presents the 66% of disease-free survival.