Bisphosphonates for secondary bone cancer
Bisphosphonates are drugs commonly used to treat secondary cancer in the bones.
There are two types of cells found in bone: osteoclasts and osteoblasts. Osteoclasts destroy old bone and osteoblasts deposit new minerals and build new bone. Cancer cells that have spread to the bone produce chemicals that change the activity of these cells, upsetting the normal balance. The osteoclasts become overactive, so more bone is broken down. This commonly causes small holes in the bone.
Bisphosphonates work by reducing the activity of the osteoclasts. Although bisphosphonates aren’t a treatment for the cancer itself, they can prevent further bone loss, helping to reduce the breakdown of bone and strengthen existing bone. Your doctor may recommend that you have treatment with bisphosphonates to treat bone pain, prevent broken bones and reduce the need for radiotherapy treatment. Bisphosphonates are also used to treat high calcium levels in the blood.
Commonly used bisphosphonates are:
- sodium clodronate (Bonefos®, Clasteon®, Loron 520®)
- ibandronic acid (Bondronat®, Bonviva®)
- disodium pamidronate (Aredia®)
- zoledronic acid (Zometa®, Aclasta®).
Bisphosphonates may be given as a drip (infusion) into a vein (intravenously), which is often given in the outpatient department every 3-4 weeks. Each treatment usually takes 15-60 minutes.
Some bisphosphonates are taken as tablets or capsules. If you are given tablets or capsules to take, you’ll be asked to take them on an empty stomach at least half an hour before food. You can’t eat or drink for six hours (usually overnight) before taking some of the tablets, and they should be taken when you’re sitting or standing, not lying down. This helps the drug move quickly into the stomach and reduces the risk of it staying in the throat or gullet where it can cause irritation. Your doctor, nurse or the pharmacist will explain how you should take your tablets.
Side effects of bisphosphonates may include pains in the muscles and joints, and low levels of calcium in the blood. Some people experience flu-like symptoms, which usually settle after the first dose. Oral bisphosphonates (taken by mouth) may also cause indigestion and a sore throat or inflamed gullet.
Your doctor will probably advise you to take calcium and vitamin D supplements to prevent a low level of calcium in the blood and to strengthen your bones while you’re taking bisphosphonates.
A very rare side effect of bisphosphonates is osteonecrosis of the jaw. This is when healthy bone tissue in the jaw becomes damaged and dies. It happens more commonly in people who have teeth removed or other dental procedures while taking bisphosphonates. It’s also more common when bisphosphonates are given by injection rather than as tablets or capsules. It can result in poor healing of the gums or loosening of the teeth.
Before taking bisphosphonates, you should have a dental check-up if you’ve not seen a dentist for six months or if you have dentures that don’t fit well. It’s also important to let your dentist know you’re taking bisphosphonates. This is because any dental extractions (removal of a tooth or root) or implants should be avoided during treatment. It’s still all right to have tooth filling, scaling, polishing or gum treatments. If your dentist decides you need to have a dental extraction, you should let your doctor know before you have any treatment. Your doctor may temporarily stop your bisphosphonates while you have the extraction and until the tooth socket has fully healed.