If doctors suspect your child has a bone tumor, it is important that the child is diagnosed and treated by a team experienced in working with children with cancer. Most doctors will begin by taking an X-ray of the bone. Following an X-ray, doctors may also recommend other imaging tests such as an MRI to better define the location and size of the cancer, and identify whether other structures around the bone are affected.
In addition to imaging tests, doctors will also perform a biopsy. During the biopsy, a piece of the tumor is removed and is examined under a microscope by a pathologist. Biopsies must be performed by an experienced surgeon specializing in bone and who has knowledge of bone cancers, called an orthopedic oncologic surgeon, to assure that the appropriate biologic tests are done on the sample and that the biopsy does not interfere with future surgical planning.
Osteosarcomas are described by their location: central tumors arise inside the bone while surface tumors arise on the outer surface of the bone. Each type has a number of subtypes. Conventional central osteosarcomas account for the vast majority of osteosarcomas in children and adolescents.
Before treating osteosarcoma, doctors need to know exactly how much of the cancer is present in the body both at the site of the tumor and elsewhere in the body. To evaluate this, a variety of tests may be performed, including scans of other parts of the body to see if the tumor has spread. The most common sites for osteosarcoma to spread are the lungs and other bones, which can be evaluated by a CT scan of the chest and a bone scan, respectively. Doctors use the following terms to describe osteosarcoma and develop treatment plans:
- Localized: the tumor is limited to the bone of origin and the tissue surrounding the tumor; it has not spread to other parts of the body.
- Metastatic: the tumor has spread from its original site in the bone to other parts of the body.
- Recurrent: the tumor has come back after treatment. It can recur in the same place that it started, or in another part of the body. The lungs and bones are the most common sites of recurrent tumors.
- Initial response to therapy: an important prognostic (predictive of treatment success) factor is the patient’s response to initial therapy. Patients whose tumor cells have nearly all been eliminated after the initial 10 weeks of chemotherapy have a better outlook than those whose tumor cells do not respond as well to treatment. Investigators are working on finding biological differences that distinguish responsive from unresponsive tumors. If this can be determined at the time of diagnosis, treatment could be better tailored and could potentially improve the outlook for patients with less responsive tumor types.