The other thing that is interesting about prostate cancer

The other thing that is interesting about prostate cancer is that we now have two different kinds of agents that we can use for treating prostate cancer with extensive bone metastases. What we are actually treating is the bone pain itself. These are two relatively new agents. One is called strontium, also known as Metastron, and the other is called Quadramet. They are both agents which go to newly forming bone. You’re going to see newly forming bone around any bone marrow metastases and then you deliver a very high, focal dose of radiation to the metastases themselves and it’s very effective for the bone pain. Remember prostate cancer patients live a long time, even when it’s fairly end stage. Bone pain is the main thing that affects their quality of life. So bone scans are also done to determine whether a patient is a candidate for this type of therapy.
With lung cancer, some people do it for the initial staging of all patients with lung cancer. Some restrict it to only patients with bone pain. Again, you would do it with anyone who develops bone pain who has that diagnosis.
Other malignancies. In general the rule of thumb is if the patient is symptomatic with bone pain. Most other malignancies are much less likely to metastasize to the bone. Osteosarcoma. It’s used for staging and for routine followup.
How do you interpret the results of a bone scan that’s been done for metastatic disease? One thing you always have to remember is that the bone scan is the most sensitive study, more sensitive than radiographs, but it is less specific. We often recommend plain films to either confirm a benign cause of lung pain or to confirm a malignant metastasis. If the x-ray does that, if it confirms a benign cause or confirms the metastasis, you’re fine. If it’s normal, you have to presume that that’s due to metastatic disease and again that’s because the bone scan is more sensitive than the plain films.
MRI is very good for looking at the bone marrow. Therefore it’s very good at looking at bone metastases because they generally spread through the bone marrow. Thin cut CT is better for looking at the bone cortex so you might want to use that if there is a suspicion of a fracture. You may even need a biopsy. Let’s say you have somebody who’s just been diagnosed with cancer, has a single lesion on the bone scan, the plain films are normal and you need to know if they are Stage IV or not. Then you would really have to go to a biopsy. Followup bone scans are also something that can potentially help you if you don’t need to make an immediate treatment decision.

Some other nononcologic indications for bone scans include stress fractures. Again, what you’re looking at is stress fractures versus shin splints. This is that young athlete, that fanatical person that exercises for hours and hours every day, they’re training for something, they’re on the high school track team or whatever it is and these people do not want to stop. They want you to tell them that their pain is due to something that is reversible and they can continue to exercise. With stress fractures, that’s not possible. These require six weeks of inactivity in order to heal. X-rays are often, if not always, normal. Shin splints, on the other hand, will usually recuperate in a very short period of time and the patient can resume their exercise.

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