I am looking for some information about bones cancer :
- Are they caused by metastasis from primary cancer ?
- Is it a cancer of the marrow or of the bone itself ?
- What are the symptoms ? (pain, fractures ...)
- When you have a bone cancer, is it located or does it spread out in all
  you bones ?
- Is it treatable ? Chances of surviving ?

Thanks for answering,

Bone cancers can metastasize to other organs.

You need to know what kind of bone cancer.  Treatments and survival
probabilities depend on the type and whether it is localized or not, to
name just a few factors.

Chondrosarcoma, osteogenic sarcoma, fibrosarcoma, and Ewing's Sarcoma
all behave differently.

The survival rate for Ewing's (a childhood bone cancer mainly) was about
8% (5-yr) in 1962.  It exceeds 50% now.  Survival probabilities much better
if in the extremities and localized.  Although surgery might be indicated
for some situations, the prevalent treatment includes 5-6 krads
radiation to the affected region and adjuvant multiple-agent
chemotherapy for approx 18 months.

Osteogenic sarcoma treatment usually involves resection of the affected
bone tissue.  Recent studies indicate success with adjuvant chemotherapy
regimes.  

Metastasized cancers (to the bone) are different...treatment would be a
function of type; complicated.

Get expert medical help, especially cell type, etc.