There are a number of staging systems, but the TNM staging system is the most common. "T" refers to the size of the tumor, "N" to the number of lymph nodes involved, and "M" to metastasis. TNM staging measures the extent of the disease by evaluating these three aspects and assigning a number to each aspect, usually between zero and 4. An example of staging in breast cancer is as follows:

T1: Tumor ≤2.0 cm in greatest dimension

N0: No regional lymph node metastasis

M0: No distant metastasis

The prognosis, or probable course or outcome of the cancer, is based not only on the staging of the cancer but also on other factors, including age, physical fitness, the size of the tumor, how aggressively, or quickly, the cancer is growing, and, possibly, the genetic makeup of the cancer. While, it is generally true that the lower the stage, the better the outcome, all factors, not just staging, need to be considered.

Osteoporosis refers to a disease in which the bones become extremely porous, in other words, they lose mass and density. Therefore, they are subject to fracture and heal slowly. Osteopenia is a similar but less serious condition of bone. Both of these conditions are defined by T-scores, which indicate a measure of bone density compared with the bone density of a young (30-year-old) "normal" person.

• A pathology report based on observation of the abnormal cells under a microscope
• Visualization of abnormal masses using high-tech machines that create images, such as x-ray, computed tomography (CT), positron emission test (PET), magnetic resonance imaging (MRI), and combined PET/CT images
• Tumor marker tests that detect substances in blood, urine, or other tissues that occur in higher than normal levels with certain cancers
• Special laboratory evaluations of the genetic make-up (the DNA) of the abnormal cells

For patients who have painful metastases to bone that are threatening to cause fracture or spinal cord compression, radiation therapy may be used. In patients who already have spinal cord compression, radiation can aid in halting and reversing potential neurologic complications. The traditional form of radiation therapy is external-beam radiation, in which x-ray treatment is delivered from outside the body, through the skin, directly to the area of affected bone. There are other forms of radiation therapy, such as intravenously administered radionuclide pharmaceuticals that target bone specifically. This approach is especially useful when a patient has many bone metastases, when external-beam radiation alone cannot treat them all sufficiently.

Surgery has a selected role in the treatment of bone complications and is generally reserved for patients who have impending fractures that cannot be addressed with radiation therapy alone. Surgery also can be used to stabilize bone in patients who have had a fracture or spinal cord compression, taking pressure off the spinal column.

Pain medications are the mainstay of managing a patient with cancer-related pain, whether the pain is from bone complications or otherwise. Drugs called bisphosphonates are helpful in slowing or stopping the deterioration of bone and progression to osteoporosis (bone loss), and in helping to lower the rate of fractures, spinal cord compression, and bone pain.

Radiation therapy, or radiotherapy, for the treatment of cancer uses ionizing radiation delivered externally or internally. Radiation therapy works by damaging the DNA in the cancer cells, therefore, interfering with the reproduction and growth of those cells. The cells then die and the tumor shrinks.

Radiation therapy is not painful; however, because the radiation used to damage or destroy cancer cells can also damage normal cells, side effects may occur. For example, the skin where radiation therapy is aimed may feel like it has been sunburned and will need to be protected from the sun. External-beam radiation does not cause you to become radioactive, so you pose no risk as a source of radiation exposure to people near you. If you are receiving your radiation therapy internally and have a radioactive implant in place, some visitors, such as pregnant women and small children, will not be allowed to get too close to you, and visiting time may be limited or restricted until the implant is removed.

Generally, the risk of side effects with radiation therapy is usually outweighed by the benefits of killing cancer cells. Any side effect you experience will be carefully monitored by the radiation oncologist. The risks, problems, and side effects that can occur with radiation depend on the type and dose of radiation being administered, and the part of the body that is being treated.

• The size of the tumor
  – Pain may occur when the tumor is large enough to press on surrounding tissue or block internal structures, such as the bowel.
• Pressure on nerves caused by the tumor
• Destruction of bone by the cancer or the cancer treatment
• Compression of the spinal cord, leading to severe neck, back, or leg pain

Pain may also result from the procedures used to treat your cancer, such as surgery, radiation treatments, and chemotherapy.