I agree - this is so unfair. This is a diagnosis that is heartbreaking no matter how many times I see it. Unfortunately, the cause of osteosarcoma is unknown. The cancer comes from cells that normally make bone. At some point in their lives, they acquire mutations in their DNA which cause them to become cancerous. Most likely there is a component of inherited genes that makes certain people more susceptible than others.
The prognosis of osteosarcoma and overall survival depends on its stage. Basically the stage of the cancer is determined by the size of the tumor and the presence or absence of metastasis. No matter what stage the disease presents itself, the tumor must be cut out surgically. This sometimes means amputation of the effected limb (though not always). Stage 1 disease has an excellent overall prognosis with most people surviving the cancer. Stage 3 disease is more advanced, and the likelihood of long term survival (more than 10 years) is much less.
The type of doctor
that your friend's daughter must see is an oncologist
. The oncologist will be responsible for the staging of the cancer, and the administration of chemotherapy. An orthopedic surgeon
specially trained in bone cancers will also be involved in the resection of the tumor. I wish her the best of luck.