Bone Mets Can Change the Basic Structure of Bones

Cancer that originates in an organ like the breast, prostate, lung etc. can spread when tumor cells break away and enter the blood stream or lymph system. It is not easy for breakaway cells to survive the body’s defenses and implant elsewhere. However, if they implant in bone, it is called bone mets (short for bone metastasis).

Healthy bones are not rigid, unchanging structures like steel beams in a building. Instead, they change and adapt in a process called remodeling. Two types of bone cells, osteoblasts and osteoclasts, are key players in this process. Osteoclasts break down old bone tissue for the body to reabsorb and dispose of it. This makes room for osteoblasts to deposit new bone tissue. However, under certain conditions this normal process can become unbalanced either in the direction of too much bone build-up (osteoblastic lesions) or too much bone reabsorption and gradual disappearance (osteolytic lesions or lytic lesions). Imbalance can be triggered such things as placement of an artificial joint replacement, infection, arthritis, inflammation, cysts, primary bone cancer, and bone mets.

Bone mets can cause either type of lesion. For instance, prostate cancer is more likely to lead to osteoblastic lesions, whereas a type of blood cancer called multiple myeloma is more likely to create lytic lesions. In some patients, both types occur in the same bone area.

Osteoblastic lesions
More bone is produced than is taken away. “The tumor somehow signals to the bone to overproduce bone cells and result in rigid, thickened, inflexible bone being formed.” This leads to bones that are abnormally hard, which in turn compromises skeletal integrity. If it occurs in the spine, it puts pressure on the nerves and nerve branches of the spinal cord, causing back pain and referred pain along the nerves. On X-rays, osteoblastic lesions show up as whiter areas than the gray bone around them because they are dense.

Osteolytic or lytic lesions
More bone is lost than is produced, resulting in thin, porous fragile bones. This type of damage makes bones prone to fracture, even during normal activity. If it occurs in the spine, the vertebrae (bones that make up the spinal column that houses the spinal cord) compress and collapse. This is very dangerous, since the damage to the spinal cord can result not only in pain or numbness, but paralysis. On X-rays, lytic lesions show up as dark areas due to the holes or spaces.

Early detection
It is important to find and treat bone lesions early before extensive pain and disability can occur. Pain is usually the first symptom, but often oncologists who are tracking a patient’s advanced cancer will discover early bone activity from a routine whole body MRI or other imaging. There are many treatments that can help preserve bone integrity, and even help restore a better balance between osteoblasts and osteoclasts. It is especially important for patients to notify their doctors of any new pain, particularly bone pain. Countless patients with bone mets enjoy high quality of life, provided they are diagnosed while they can be well managed.

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¹ “Bone Metastasis Treatment with Medications.” https://www.oncolink.org/cancers/bone/bone-metastases/bone-metastasis-treatment-with-medications