Bone Metastases: Pain, Fractures, and Treatment

Bone metastases are deposits of cancer that started somewhere else in the body and have settled in bone. They are not a new, separate bone cancer. Breast cancer in a rib is still breast cancer, and it is treated as breast cancer.

Bone is the third most common place for cancer to spread, after the lung and the liver. The spine is hit most often. Then come the thigh bone, the pelvis, the ribs, the breastbone, the upper arm bone and the skull.

Cancer in bone upsets the normal cycle of bone being broken down and rebuilt. Some deposits eat bone away and leave a hole. These are called lytic, and they are typical of breast, lung and kidney cancer. Others lay down dense, disorganised bone. These are called blastic, and they are typical of prostate cancer. Either kind makes bone weaker than it looks.

Go to the emergency department today, not next week, if any of these start. Nerve function that is already lost when treatment begins often does not come back.

Signs of spinal cord compression, where a deposit presses on the spinal cord:

• New or changed back or neck pain that is worse when you lie flat, worse at night, or worse when you cough, sneeze or strain.
• A band of pain that wraps around your chest or belly.
• Weak, heavy or clumsy legs. Trouble climbing stairs, or a foot that catches when you walk.
• Numbness or pins and needles in both legs, or numbness in the saddle area, meaning the inner thighs, buttocks and groin.
• Any change in bladder or bowel control. Trouble starting a stream, dribbling, not feeling when you need to go, or leaking.

Say the words "I have cancer and I think this may be spinal cord compression." Ask for an urgent MRI scan. The UK national guideline says the scan should happen as soon as possible, and always within 24 hours. Do not accept an appointment weeks away.

Signs of high calcium in the blood, called hypercalcaemia of malignancy:

• New confusion, drowsiness, or acting out of character.
• Heavy thirst and passing large amounts of urine.
• New constipation, feeling sick, being sick, or belly pain.
• Deep tiredness and muscle weakness that came on over days.

Also seek urgent care for:

• Sudden severe pain in a limb or the back after a small knock, a twist, or nothing at all. That can be a broken bone.
• A limb you cannot put weight on, or one that looks bent or short.
• A temperature of 38.0 °C / 100.4 °F or higher. The CDC uses 100.4 °F and the NCI uses 100.5 °F. Use the lower number.

Back pain is the first sign in 80 to 95 percent of people who turn out to have spinal cord compression. Weakness follows in 35 to 75 percent. The pain usually comes first, and that gap is your chance.

The reason for the hurry is blunt. In one national review, of the people who could still walk unaided when they were diagnosed, 81 percent were walking a month later. Of those who could no longer walk at diagnosis, 67 percent had recovered no function at all a month later. Not being able to walk for more than 48 hours before diagnosis is linked to poor recovery.

MRI is the scan that answers the question, with about 93 percent sensitivity. A steroid such as dexamethasone is usually started straight away to reduce swelling around the cord, while radiotherapy or surgery is arranged. The dose is set by the team treating you.

Bone breakdown releases calcium into the blood. Around 20 percent of people with cancer develop high calcium at some point. Blood levels above 12 mg/dL are moderate, and above 14 mg/dL are severe. In many labs that is roughly 3.0 and 3.5 mmol/L.

The symptoms are easy to blame on the cancer, the opioids or plain exhaustion. Confusion, thirst and constipation together should raise the question. Treatment usually starts with fluids into a vein, then a bone-modifying drug. It works, and people often feel much clearer within days.

Plain X-rays are the least sensitive test. A deposit may not show up until about half the mineral in that patch of bone has gone. So a normal X-ray does not settle the matter.

A bone scan picks up about 78 percent of deposits and shows the whole skeleton at once. CT is better at showing how much bone has been destroyed. MRI is the best test for the spine and the nerves. PET-CT is the most sensitive of all.

Blood tests may show high calcium, or a rising alkaline phosphatase. Sometimes a biopsy is needed to prove that a spot really is cancer, especially if it is the first sign of spread.

Radiotherapy is the main treatment for a painful spot. It eases pain in 50 to 80 percent of people. A single dose of 8 Gy works as well as a longer course for straightforward bone pain, which means one visit rather than ten. StatPearls notes the single dose does carry a higher chance of needing retreatment, about 20 percent against 8 percent.

Bone-modifying drugs slow the cells that dissolve bone. These are bisphosphonates such as zoledronic acid or pamidronate, given by drip, or denosumab, given as an injection under the skin. They cut the rate of fractures and other bone events. You will be asked about dental work before starting, because of a rare jaw problem, and you may be given calcium and vitamin D.

Surgery is used when a bone is about to break or already has, and to take pressure off the spinal cord. Rods, plates, screws and cement can make a bone weight-bearing again. Cement injected into a crushed spinal bone, called vertebroplasty or kyphoplasty, can settle severe pain.

Systemic treatment aimed at the cancer itself, such as hormone therapy, chemotherapy or targeted drugs, still does much of the work. Radiopharmaceuticals such as radium-223 travel through the bloodstream to many bone deposits at once.

Ask directly which bones have deposits and whether any of them limit what you should do. Ask whether a hip or thigh bone needs checking before you keep walking on it. A weak bone found early can be fixed on a planned list. A broken one is fixed as an emergency.

Keep a simple pain diary: where, how bad out of ten, what makes it better and worse, and how much breakthrough medicine you used. Pain that is steadily climbing, or a new site of pain, is information the team needs before your next visit, not at it.

Ask about physiotherapy and occupational therapy early. Rails, a raised toilet seat, a walking stick and a shower stool reduce falls, and falls are how many bones break.

• StatPearls (NCBI Bookshelf) — Bone Metastasis
• StatPearls (NCBI Bookshelf) — Spinal Cord Compression
• StatPearls (NCBI Bookshelf) — Malignancy-Related Hypercalcemia
• NICE (NCBI Bookshelf) — Spinal metastases and metastatic spinal cord compression, NG234
• NICE (NCBI Bookshelf) — Metastatic Spinal Cord Compression, CG75
• American Cancer Society — Bone Metastases
• National Cancer Institute — Metastatic Cancer
• Centers for Disease Control and Prevention — Fever and Cancer Treatment