Stage 4 or metastatic kidney cancer occurs when kidney cancer spreads to other parts of the body. Approximately 2 in 10 people have metastatic kidney cancer at the time of the initial diagnosis, and as many as 4 in 10 people experience cancer spread after kidney removal (nephrectomy).

Renal cell carcinoma (RCC) is the most common kidney cancer. It’s estimated that 1 in 3 people with RCC will develop bone metastases (bone mets), which means the cancer spreads to the bones. 

From the community: “Most of you have probably already heard that RCC likes to spread to bones. If you are stage 4, or otherwise on long-term watch and wait, your oncologist has probably ordered regular bone scans in order to keep an eye out for this contingency. This was the case with me until two months ago when a PET scan revealed massive uptake in my left clavicle and right femur. The clavicle nodule (Neville) caused some minor annoyance. I would get little stabs of pain every once in a while, especially if I exerted pressure on the nodule with my index finger. The femur nodule (Nigel) caused no problems at all… The radiation oncologist sent me for an x-ray so that we could see what was going on. Sure enough, there was a fracture right through the nodule site. I don't remember a specific activity that caused the bone to break. It could have been when I took a heavy package from the mailman; or it could have been when I got tangled up putting on my sweatshirt. We are treating the fracture with immobilization and pain meds… We are also going to go ahead with radiating Neville before he makes things worse… I am posting this information to alert my fellow RCC patients that bone mets are not only possible but quite serious. I wish that I had been more cautious with the stress that I put on my body. I suppose that I thought there would be a considerable amount of time between when the first bone met was diagnosed and when it caused problems. Not so, apparently. If you suspect you have a bone met it might be time to make some changes in your lifestyle - or at least your wardrobe.” – Inspire member

What are bone metastases (bone mets)?

Metastases are cancerous tumors that form in other parts of the body after cells from the primary cancer (kidney cancer) break away from their original location. These cells circulate in the bloodstream or lymphatic system. When the cancer cells settle in the bones, they cause a new, secondary form of cancer or bone mets.

Bone mets aren’t the same as bone cancer. The two diseases have different causes and treatments. Because kidney cancer causes the bone mets, your oncologist (cancer doctor) will use kidney cancer treatments to treat these tumors — not bone cancer treatments.

How does metastatic kidney cancer affect the bones?

Bone mets affect the skeletal system. The spine is the most common site for bone mets, but this secondary cancer can also settle in the hips, femur (upper leg bone), humerus (upper arm bone), ribs, and skull. 

Bone mets affect the bone cells responsible for breaking down old bone (osteoclasts) and building new bone (osteoblasts). The cancer cells may intensify the activity of:

• Osteoclasts: Overactive osteoclasts cause bone to dissolve quickly without new bone ready to replace it. Holes called osteolytic or lytic lesions form in the bones, making the weakened bone more prone to fractures. 

• Osteoblasts: New bone gets made before the old bone breaks down. The bones get harder, causing sclerosis. Osteoblastic or blastic lesions form in these hardened areas of bone. Although the bone is hardened, the bone structure isn’t normal. As a result, the bone breaks more easily. 

What are the symptoms of bone metastases?

Common signs of bone metastases (bone mets) include:

• Bone pain: In the beginning, this bone pain may come and go. It may get worse at night and get better when you move. As the disease progresses, bone pain may become constant and worsen with activity. 

• Broken bones: You may experience a fracture for no known reason, or you may break a bone during a fall or other injury. 

• Back pain: A sudden onset of back pain may indicate a spinal fracture. The bone mets can weaken the spine, causing a fracture even without an injury preceding it. 

• Spinal cord compression: Pressure on the spinal cord (spinal cord compression) from cancer in the bones can cause severe neck and back pain. In addition, you may have pain that shoots down one or both legs, leg weakness or numbness, abdominal numbness, and an inability to hold in urine or feces (incontinence).

• Hypercalcemia: Cancer can cause bones to release an excess of calcium into the bloodstream. Elevated blood calcium levels (hypercalcemia) can cause extreme thirst, fatigue, constipation, frequent urination, confusion, and muscle pain and weakness. If not treated, it can lead to coma and kidney failure.

How are bone mets diagnosed?

At the time of the initial kidney cancer diagnosis, you’ll get tests to determine which parts of the body the cancer affects. These tests are part of kidney cancer staging and help your doctor choose the most effective treatments.

You may also undergo testing if you have symptoms of bone mets or to check for metastatic cancer even if you don’t have symptoms.

Doctors use imaging tests to look for bone metastases. These tests include:

• Blood tests to check for elevated levels of calcium and alkaline phosphatase (ALP), an enzyme found in bones.

• Urine test to measure substances released by damaged bones. 

• X-rays to assess bone density (holes in bone or bones that are too hardened) and look for fractures.

• Bone scans using small amounts of a safe, injectable radioactive tracer and a nuclear imaging scanner. Cancer cells absorb more of the tracer, which shows up on the images. A bone scan of the entire skeletal system may detect bone mets sooner than X-rays.

• CT scans find osteolytic lesions, which don’t show up as well on bone scans. This scan can also show the shape and size of tumors. Your doctor may also take a sample of the bone cells or tissue during a CT-guided needle biopsy. 

• MRIs identify spinal compression and joint problems. The scans help doctors identify tumors, bone damage, and bone infections.

From the community: “A bone metastasis was how my RCC was identified. A lytic lesion as found on C2 and after stabilisation of my neck, a scan was conducted to find the primary which turned out to be clear cell RCC, so I had a radical nephrectomy. I also have a metastasis at T6 but that has never been active. I am in my ninth year of TKI treatment.” – Inspire member

What are bone metastases treatments?

Treatments for bone mets depend on the primary cancer, previous cancer treatments, and the affected bones. They include:

• bisphosphonates and denosumab

• systemic treatments 

• local treatments

• clinical trials

Bisphosphonates and denosumab

Bisphosphonates and a drug called denosumab are the most common treatment for bone mets. These drugs slow the actions of osteoclasts, which in turn slows bone loss. The drugs also ease bone pain while lowering the risk of fractures and hypercalcemia. You receive this medicine monthly through an IV or under the skin (subcutaneous).

Bisphosphonates include:

• pamidronate

• zoledronic acid

If you take bisphosphonates, your doctor will monitor you closely for signs of a rare, but serious medication side effect called osteonecrosis of the jaw (ONJ). Part of the jawbone dies, leading to a nonhealing open sore, infection, and tooth loss. Good oral hygiene can help lower this risk.

Systemic treatments for bone metastases

Systemic treatments for bone mets include:

• chemotherapy

• immunotherapy

• radiopharmaceuticals (medicines with radioactive elements that settle in bone to fight cancer)

• targeted therapy

Local treatments for bone metastases

Local treatments target cancer that affects only one bone or severe metastases in a certain skeletal area that requires immediate treatment. 

Local treatments for bone mets include:

• radiation therapy, including stereotactic body radiation therapy to precisely deliver high doses of radiation directly to tumors

• radiofrequency ablation using an electric current to heat and destroy bone tumors

• bone cement to strengthen or stabilize bones at risk for fractures

• surgery to place screws, rods, plates, or other devices that stabilize and support bones

Clinical trials

You can also talk to your doctor about participating in a clinical trial. A clinical trial provides the opportunity to try new therapies still in development.

From the community: “… my husband has had RCC for 14years and had a tumour in his hip that spread into his femur... it was surgically removed, and since then has been on Sutent then Tivozanib and apart from a small tumour in his right arm that was fortunately destroyed by radio therapy , his remaining metastatic tumours in his lungs and Pancreas have been kept under control, hopefully your husbands cancer might like my partner turn out to be of an indolent nature, and remember long term survival rates are improving each year.” – Inspire member

What’s the outlook for people with metastatic kidney cancer?

Survival rates for people with metastatic kidney cancer continue to improve, but many factors influence the prognosis. As many as 1 in 14 Americans with metastatic kidney cancer live five or more years after receiving the diagnosis.

Sources

• Bone metastasis. American Cancer Society. May 2016.

• Bone metastases. American Cancer Society. August 2021.

• Chen SC, et al. Bone metastasis from renal cell carcinoma. International Journal of Molecular Sciences. June 2016.

• Fleckenstein FM, et al. Renal cell carcinoma metastatic to the liver. Translational Oncology. October 2016.

• Umer M, et al. Skeletal metastasis in renal cell carcinoma: A review. Annals of Medicine and Surgery. March 2018.

Disclaimer

Member comments are lightly edited for length and to remove identifying information but are otherwise reproduced as they appear in the community as part of public posts.

This content is for general informational purposes only and does not necessarily reflect the views and opinions of any organization or individual. The content should not be used as a substitute for professional medical advice, diagnosis, or treatment. Please consult your healthcare provider about any questions you may have regarding a medical condition.