The diagnosis of secondary bone cancer

Your doctor is likely to arrange a number of tests for you if they think it is possible that your cancer has spread to the bones. A blood test may be done to check your general health and the level of calcium in your blood. You will also probably have a chest x-ray to see if there are any signs of cancer in the lungs. Other tests may include:

Bone x-ray

This is a simple x-ray that can show up certain changes in the bone and may show that a secondary bone cancer is present. A cancer of the bone may not always show up on a bone x-ray though.

Bone scan

This is a more sensitive test than the simple x-ray and shows up any abnormal areas of bone more clearly.

A small amount of a mildly radioactive substance is injected into a vein, usually in your arm. Abnormal bone absorbs more radioactivity than normal bone, so these areas are highlighted and picked up by the scanner as hot spots.

There is generally a wait of approximately 2-3 hours between having the injection and the scan itself, so you may like to take a magazine or book with you to pass the time.

The level of radioactivity used in the scan is very small and does not cause any harm to your body.

Even if an abnormality is detected on the bone scan, it is not always clear whether it is caused by cancer or by another condition such as arthritis. Sometimes a CT or MRI scan may help the doctors to decide whether the changes seen on a bone scan are caused by secondary bone cancer or another condition.

MRI (magnetic resonance imaging) scan

This test uses magnetic fields to build up a series of cross-sectional pictures of the body.

During the test you will be asked to lie very still on a couch inside a metal cylinder that is open at both ends. The whole test may take up to an hour and is painless – although the machine is very noisy. You will be given earplugs or headphones to wear.

The cylinder is a very powerful magnet, so before entering the room you should remove any metal belongings. If you have any metal inside your body, for example, a heart monitor, pacemaker, surgical clips, or bone pins you should tell your doctor. You might not be able to have an MRI because of the magnetic fields.

You may feel claustrophobic inside the cylinder. It may help to mention to the radiographer doing the MRI if you do not like enclosed spaces. They can offer you extra support during your scan.

Some people are given an injection of dye into a vein in the arm, but this usually does not cause any discomfort.

CT (computerised tomography) scan

A CT scan takes a series of x-rays, which builds up a three-dimensional (3D) picture of the inside of the body. The scan is painless and takes longer than an x-ray (from 10-30 minutes).

Some people may be asked not to eat or drink for a few hours before the scan. Most people who have a CT scan are given a particular drink or injection just before the scan to allow certain areas to be seen more clearly. Sometimes, both a drink and an injection may be given.

For a few minutes, this may make you feel hot all over. If you are allergic to iodine or have asthma, you could have a more serious reaction to the injection. You should tell your doctor beforehand as you can usually still have the injection, but may need to take steroids for the day before and on the day of the scan.

You will probably be able to go home as soon as the scan is over.

PET (positron emission tomography) scan

A PET scan uses low-dose radioactive sugar to measure the activity of cells in different parts of the body. A very small amount of a mildly radioactive substance is injected into a vein, usually in your arm. A scan is then taken. Areas of cancer are usually more active than surrounding tissue and show up on the scan.

This is a new type of scan and you might have to travel to a specialist centre to have one. PET scans are not often necessary, but you can discuss with your doctor whether one would be useful in your case. The use of PET scans to diagnose secondary cancer in the bone is still being researched, but it is thought that these scans can help to show whether the bones are affected by other (non-cancerous) conditions or by cancer.

Very occasionally, after scans, the doctors may still not be certain of the cause of the abnormality in the bone and you may need to have a small sample of cells taken from the affected area of bone (a biopsy).

Biopsy

A biopsy can be carried out in either of the following ways:

Needle biopsy

This test involves taking a sample of bone and examining it to see if it contains cancer cells. A needle is passed through the skin into the bone, and a small piece of the bone is taken. This is examined under a microscope. This part of the test can be painful so, before the sample is taken, a local anaesthetic is injected to numb the area. If you are feeling very anxious, a sedative injection may also be given.

The test does not take very long and you may have it as an outpatient. If the sample is taken from your back, you may need to stay in hospital overnight.

You may have to wait about 10-14 days for the results of the needle biopsy.

It is not uncommon to have some discomfort for a few days after the test. Your doctor will prescribe painkillers for you.

Open biopsy

For this test, a small piece of bone is removed while you are under a general anaesthetic. Bone is extremely hard, and the piece that has been removed has to be softened so that it can be examined under a microscope. The softening process takes several days, and means you may have to wait 10-14 days for the results of the biopsy.

If a secondary bone cancer is found before the primary cancer

If a secondary cancer in the bone is found before a primary cancer is diagnosed, your doctor may arrange for you to have tests to find the primary site. For example, your doctor may ask you to have:

• a mammogram to look for primary cancer in the breast
• a prostate ultrasound and a blood sample to check for prostate cancer
• a chest x-ray and CT scan to check for lung cancer

Your doctor, together with other medical staff, will look at the results of all your tests before a firm diagnosis can be made. This may take some days, or possibly a few weeks. The waiting period may be a worrying time for you, but it is very important that an accurate diagnosis is made. You may find it helpful to have the support of a relative, a close friend or a support organisation while you are waiting for your test results.