Cancer is an abnormal condition which occurs once the normal cells start to know an uncontrollable and rapid growth and an even faster death while the cancerous cells tend to multiply at a fast pace and outlive the normal ones; if the tumor spreads far from the primary site to other surrounding parts of the internal body and develop new and secondary tumors then the cancer will eventually become metastatic. If the cancerous cells have entered the bloodstream, they will end up in any tissue or organ; these cells can also travel through the lymph system, which includes the lymph vessels, where a clear fluid called lymph is carried to the heart, being somehow similar to the blood vessels, and the lymph nodes. Basically, the cancer becomes metastasized only when the primary tumor, which is already locally advanced, continues with its spreading and the cancerous cells have reached out from the prostate capsule.

The cancer will be named after the body part from where it started, even if the tumor has spread and invaded some other body parts and usually, when there are two or more metastatic tumors, this condition is called metastases. Sometimes doctors find it hard to identify the primary site of the cancer: in this situation the disease is called cancer of unknown primary and when the cancer comes back as metastases, refer to this condition as distant recurrence. The bone structures are the third most common site affected by the metastatic cancer, either being a breast cancer, a prostate cancer or any other type of cancer. The carcinomas are more likely to metastasize to bone in comparison to the sarcomas and the most common bone sites affected by the metastatic cancer are the spine, the pelvis or the hip, the femur or the upper leg bone, the ribs, the humerus or the upper arm bone and the skull. Usually the distant bone structures are less likely to get affected if the patient starts a treatment.

The symptoms often associated with bone metastasis are pain, hypercalcemia and pathological fractures. Metastatic cancer will cause pain, a symptom reported by almost seventy percent of the patients diagnosed with bone metastases, because prostate cancer has the predilection of affecting first the bone structures. The pain is caused because of the tumor, responsible for the stretching of the periosteum but also because of the nerve stimulation in the endosteum. The radionuclide bone scans, the coaxial tomography or the magnetic resonance imaging or MRI can confirm if the cancer has spread to the bones or not. The MRI is considered as the most sensitive method of detecting cancer because it can spot the cancerous cells long before they reach and affect the bone structures. The metastatic bone lesions are characterized as osteolytic, osteoblastic or mixed. Osteolytic lesions or tumors can cause an abnormal resorption of bone by the enzymes known as proteolytic and the spreading process outstrips the laying down of the new bone. Osteoblatic tumors cause a secretion of bone extracellular matrix proteins or ECM; in other words the tumor stimulates the bone growth. In most cases the lesions are identified as mixed.

The treatment procedures recommended for the terminal cancer stages are radiotherapy, chemotherapy and depending on the type of cancer, bisphosphonates. Chemotherapy is a popular treatment method for curing cancer and leukemia, while the radiation therapy has the effect of damaging the DNA of the cancerous cells so that it would stop their multiplication. The radiotherapy uses the internal beam radiation method by implanting radioactive seeds into the prostate gland and leaving them there to decay or the external proton beam radiation.