Adamantinoma, from the CureRays guide library.

Adamantinoma is a rare, slow-growing bone cancer that almost always starts in the shin bone (tibia); surgery to remove it completely is the only effective treatment, because it does not respond to radiation or chemotherapy.

What it is.

Adamantinoma is an unusual low-grade bone cancer that develops in the middle of a long bone — about 85% of the time in the tibia (shin), and occasionally the jaw or forearm. It grows very slowly, often over many years, and frequently causes a painless swelling or a bowing of the shin long before it is diagnosed. Under the microscope it contains both bone-forming and epithelial-looking cells, and it is closely related to a benign condition called osteofibrous dysplasia. Because adamantinoma is resistant to both radiation and chemotherapy, the entire treatment rests on removing it surgically with a wide, clean margin. The outlook is generally very good, but the tumor has a stubborn tendency to come back locally if any cells are left behind, and a minority can eventually spread — most often to the lungs and lymph nodes — sometimes years later.

How radiation treats it.

Radiation damages the DNA inside cancer cells so they can no longer divide. Adamantinoma cells repair this damage very effectively, which is why radiation rarely controls the tumor and surgery is the cure. In the uncommon situation where a tumor cannot be fully removed, modern image-guided radiation can still be used to slow it or relieve pain, delivering carefully shaped beams to the target over a series of short, painless sessions that leave no radioactivity behind.

The ways we can treat it.

Radiation — not standard. Adamantinoma is radioresistant, so radiation is not part of routine cure. It may be considered only when surgery cannot remove the tumor completely or to ease symptoms from spread that can't be operated on.

Targeted therapy for metastatic disease. For the rare patient with widespread disease that cannot be removed, targeted drugs such as sunitinib have been reported to help in case studies, since standard chemotherapy is generally ineffective.

Questions we hear often.

Why can't radiation or chemotherapy treat my adamantinoma? This tumor is naturally resistant to both. Its cells repair radiation damage and shrug off standard chemotherapy. That is why complete surgical removal is the treatment that cures it, and why getting clean surgical margins matters so much.

Will I lose my leg? Usually not. Most adamantinomas can be removed with limb-salvage surgery that rebuilds the shin bone. Amputation is reserved for tumors that have wrapped around the main nerves and blood vessels.

Could it come back? It can return at the original site if any cells were left behind, and a minority spread to the lungs — sometimes years later. That's why your team will keep checking your leg and chest with scans for a long time after surgery.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.