Bon cancer – Causes & diagnosis

What causes primary bone cancer?

The exact causes of primary bone cancer are unknown. Research is continually being carried out to try to find the causes. As many bone cancers occur in teenagers and young people it is thought that they may be related in some way to changes that occur when bones are growing.

People who have had previous high doses of radiotherapy to a bone have a slightly increased risk of developing cancer of that bone. This is still a very small risk for most people. Older people who have a type of long-term disease of the bone, known as Paget’s disease, have an increased risk of developing bone cancer.

If a person has had a benign (non-cancerous) bone tumour known as a osteochondroma or a chondroma he or she will have a slightly increased risk of developing a type of cancer of the bone known as a chondrosarcoma.

Most bone cancers are not caused by an inherited faulty gene, but some people with genetic conditions have an increased risk of developing bone cancer. People who have an inherited condition known as Li-Fraumeni syndrome have an increased risk of osteosarcoma and some other types of cancer. Children who have a rare type of eye cancer (retinoblastoma) that is caused by an inherited faulty gene have an increased risk of osteosarcoma. Another rare genetic condition called hereditary multiple exostoses (HME) can also increase the risk of developing chondrosarcoma.

It is often thought that an injury to a bone may cause cancer, but research seems to show that injuries do not cause bone cancer. An injury may draw attention to an existing bone cancer.

What are the symptoms of primary bone cancer?

The symptoms caused by a bone cancer will vary according to the particular bone that is affected and its position in the body. Symptoms will also vary according to the size of the tumour.

Sometimes the first sign may be pain or tenderness in the area of the tumour. This may start as a persistent ache that will not go away and may feel worse at night when the muscles are relaxed. In children this symptom may be mistaken for a sprain or ‘growing pains’.

Another common symptom is swelling around the affected area of bone. The swelling may not show up until the tumour is quite large. It is not always possible to see or feel a lump if the affected bone is deep within the body tissues.

If the cancer is near a joint, the lump can make it more difficult for you to move the joint and can affect movement of the whole limb. If the affected bone is in the leg you may find that you limp.

If the cancer is in the spine it may cause pressure on the nerves of the spine and lead to weakness, numbness and tingling in the limbs.

Other less common general symptoms may include tiredness, a high temperature or sweats and weight loss.

Bone cancer is sometimes discovered when a bone that has been weakened by cancer breaks after a person has had a minor fall or accident.

Many of the symptoms described above are common to conditions other than cancer. As the symptoms of bone cancer can also be caused by other medical conditions or injuries, it may sometimes take a long time for doctors to find out that the symptoms may be due to a cancer. However, anyone with persistent bone pain (lasting longer than a few weeks) should be referred to a bone specialist (orthopaedic doctor) or a cancer specialist (oncologist).

How bone cancer is diagnosed

Usually you begin by seeing your GP (family doctor), who will examine you and arrange any tests or x-rays which may be necessary. Your GP will probably refer you to a local surgeon who specialises in bone diseases, known as an orthopaedic surgeon.

The orthopaedic surgeon at the hospital will take your full medical history before doing a physical examination. This will include an examination of the affected bone to check for any swelling or tenderness. You will probably have a blood test done to check your general health.

If tests suggest that there might be a primary bone tumour your doctors are likely to arrange for you to be seen at a specialist hospital, or bone tumour centre, which will have a team of specialist doctors and nurses who are experienced in the treatment and care of people with these cancers. Many of the specific tests for diagnosing bone tumours, such as the biopsy, require experience and specialist technique.

Children are usually referred to a children’s (paediatric) hospital. Teenagers may often be referred to specialist adolescent cancer units. These units have specialist doctors with a lot of experience in diagnosing and treating teenagers with cancer. The units also have a team of people to help support teenagers. The team is known as a multi-disciplinary team and includes specialist doctors and nurses, social workers, counsellors, physiotherapists, dietitians, education specialists and psychologists.

The following tests may be used to diagnose a bone cancer.

  • X-rays
  • Bone scan
  • Core needle biopsy
  • Open biopsy

X-rays

X-rays of the bone are the simplest way of diagnosing bone cancer and telling whether the cancer has started in the bone (primary bone cancer) or has spread into the bone from a cancer elsewhere in the body (a secondary bone cancer). Sometimes the x-rays give a characteristic picture that helps the doctor to diagnose a particular type of bone cancer (this is often the case for osteosarcoma). More commonly, however, the x-rays will show either an area of bone that has been destroyed by cancer or an increased amount of new bone cells growing around the cancer.

Bone scan

Bone scans are also known as isotope bone scans. They are very sensitive and can detect cancer cells before they show up on x-ray. A very small amount of a mildly radioactive substance is injected into a vein, usually in your arm. A scan is then taken. As abnormal bone absorbs more of the radioactive substance than normal bone, this shows up on the scan as highlighted areas (sometimes referred to as ‘hot spots’).

After the injection you will have to wait for up to three hours before the scan can be taken, so you may want to take a magazine or book with you, or a friend to keep you company.

The level of radioactivity used in these scans is very low and is not harmful. The radioactivity disappears from the body within a few hours.

Core needle biopsy

A special needle is put into the affected bone to take a sample of cells. Several samples may be taken. A local anaesthetic is injected first to numb the area. If the lump is near the surface of your body and can easily be felt, the doctor will probably just feel it to guide the needle in. If the lump is in a bone deep within the body (such as in the abdomen) or is harder to feel, the doctor will use an ultrasound scan or sometimes a CT scan to see where the needle is going and guide it into the right place.

When the cells are looked at under a microscope, the pathologist will be able to tell whether they are benign (not cancer) or cancerous cells. If the lump is a cancer further tests may be done on the sample to try and find out exactly what type of bone cancer it is.

Sometimes, particularly in children, the biopsy is done under a general anaesthetic.

A needle biopsy will be able to tell whether the lump is a cancer for most people. Sometimes, not enough cells may be collected to get a clear answer, and then an open biopsy will be needed.

Open biopsy

Open biopsy means using a surgical knife (scalpel) to open the area and remove a tissue sample from the lump. If the lump is small enough, the whole of it may be removed. An open biopsy may be done under a local or general anaesthetic, depending on the position of the lump and how deep it is within the body. If the lump turns out to be benign, you may not need to have any more treatment. If it is cancer, your doctor will talk over the treatment options with you.

In the same way as for a needle biopsy, the sample will be sent to the laboratory so that it can be tested by a pathologist. Often a large number of studies will be done even on a very small sample. It can take from a few days to 10 days to have all the results. This can be a very worrying time for you, but it is very important that an accurate diagnosis is made. It may help you to talk about your worries with a partner or close friend, or you may wish to contact CancerBACUP’s information service or one of the support organisations for emotional support.

Further tests

If the tests show that you, or your child, have bone cancer your doctor may want to do some further tests to see if the cancer has spread outside the bone. Tests may also be arranged to see how well your kidneys, heart and other organs are working as these may be affected by any treatment that you have for the cancer. The tests may include any of the following.

  • Chest X-ray
  • CT (computerised tomography) scan
  • MRI (magnetic resonance imaging) scan
  • Bone marrow sample
  • PET (positron emission tomography scan)

Chest X-ray

In primary bone cancer the commonest place for the cancer to spread to is the lung. A simple chest x-ray may show whether or not the lungs have been affected.

CT (computerised tomography) scan

A CT scanner takes a series of x-rays which builds up a three-dimensional picture of the inside of the body. The scan is painless but takes longer than an x-ray (10-30 minutes). It may be used to identify the exact site of the tumour, or to check for any spread of the disease. Most people who have a CT scan are given a drink or injection to allow particular areas to be seen more clearly. For a few minutes this may make you feel hot all over. Before having the injection or drink, it is important to tell your doctor and the person doing the test if you are allergic to iodine or have asthma. It is usually still possible to have the injection, provided you have treatment of steroids on the day before and the day of the injection. You will probably be able to go home as soon as the scan is over.

MRI (magnetic resonance imaging) scan

This test is similar to a CT scan but uses magnetism instead of x-rays to build up cross-sectional pictures of your body. Some people are given an injection of dye into a vein in the arm to improve the image.

During the test you will be asked to lie very still on a couch inside a long chamber for up to an hour. This can be unpleasant if you don’t like enclosed spaces; if so, it may help to mention this to the radiographer. The MRI scanning process is also very noisy, but you will be given earplugs or headphones to wear and many hospitals will play music for you during the scan. You can take in your own favourite tape or CD. You can usually take someone with you into the room to keep you company.

The chamber is a very powerful magnet, so before entering the room you should remove any metal belongings. People who have heart monitors, heart pacemakers or certain types of surgical clips cannot have an MRI because of the magnetic fields.

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

Bone marrow sample

This test is only necessary if the type of cancer called Ewing’s sarcoma has been diagnosed or is suspected, as Ewing’s sarcoma may in rare instances spread to the bone marrow (the spongy material inside bones where blood cells are made). Small samples of bone marrow are taken from the hip bone (pelvis) and looked at under a microscope to see if they contain any abnormal cells.

The bone marrow sample may be taken under a local anaesthetic, but for children it is usually done under a general anaesthetic.

PET (positron emission tomography scan)

PET scans are a new type of scan and you may have to travel to a specialist centre to have one. They are not always necessary but you can discuss with your doctor whether one would be useful in your case.

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 normally more active than surrounding tissue and show up on the scan.

It will probably take several days for the results of your tests to be ready, and this waiting period will obviously be an anxious time for you. It may help if you can find a close friend or relative with whom to talk things over.

If the tests show that you have osteosarcoma or Ewing’s sarcoma you will have further tests to prepare you for chemotherapy.

Grading and staging of bone cancer

Grading

Grading refers to the appearance of the cancer cells under the microscope. The grade gives an idea of how quickly the cancer may develop. There are three grades: grade 1 (low grade), grade 2 (moderate grade) and grade 3 (high grade). Low-grade means that the cancer cells look very like the normal cells of the bone. They are usually slow-growing and are less likely to spread. In high-grade tumours the cells look very abnormal. They are likely to grow more quickly and are more likely to spread.

Staging

The stage of a cancer is a term used to describe its size and whether it has spread beyond its original site. Knowing the extent of the cancer and the grade helps the doctors to decide on the most appropriate treatment. There are three stages of bone cancer, partly based on the grade of your cancer.

Stage 1 bone cancer is low-grade and has not spread to lymph nodes or any other body organ.

Stage 1A means low-grade bone cancer that is still completely inside the bone in which it started. The cancer may be pressing on the bone wall and causing a swelling, but has not grown through it. Stage 1B bone cancer is low-grade, but has grown through the bone wall.

Stage 2 bone cancer is high-grade and has not spread to lymph nodes or any other body organ.

Stage 2A means the cancer is still completely within the bone in which it started. Stage 2B has grown through the wall of the bone.

Stage 3 is bone cancer of any grade that has spread beyond the bone in which it started to other organs in the body.

Recurrent bone cancer means that the bone cancer has come back after initial treatment.

Radiotherapy uses a type of radiation, called ionising radiation, to destroy cancer cells. There are several types of ionising radiation including x-rays, gamma rays and beta rays.  Most radiotherapy treatment for cancer use x-rays.

Ionising radiation works by releasing chemicals in the nucleus of cells. These chemicals, called free radicals,  damage the DNA, the genetic material that is vital for the cell to multiply.  If the DNA is sufficiently damaged by the radiation then it will not be able to divide and will die off.

In order for the radiotherapy to release the free radicals that damage the DNA there needs to be a good supply of oxygen in the cells.   If the cells are starved of oxygen then this actually protects them against the effects of the x-rays and makes treatment less effective.

Oxygen is carried to the tissues and cells in our bodies by the haemoglobin in the red blood cells. If we are anaemic then the haemoglobin level in the blood is low, and so the amount of oxygen carried by the blood to our cells is reduced.

So in order to get the best results from a course of radiotherapy it is important to be sure that you are not very anaemic before you start treatment. 

If you are anaemic then your doctors may well suggest a blood transfusion before you start your treatment.  This will boost your haemoglobin level and will increase the oxygen in your blood, which will increase the chances of success from your radiotherapy treatment.

I am going to have a course of radiotherapy to treat my cancer. The doctors took a blood test today and when I asked about this they said it was important to make sure I wasn’t anaemic before I had the treatment? Why is this?

Very often when a cancer is treated the treatment will take away all evidence of that cancer: symptoms will disappear, physical examination and special tests (like blood tests and scans) will all go back to normal. All the appearances will suggest that the problem has been cured.


But sometimes there will be microscopic traces of the cancer left behind. Because they are so tiny these traces will not cause any symptoms and they will be too small to show up on even the most careful of examinations and most sensitive of special tests. These tiny clusters of cancer cells may lie dormant for months or years but may eventually grow and the cancer may come back.

Since these minute cells that might have been left behind cannot be detected in any way it is impossible to give an absolute guarantee that a cancer has been cured after treatment.

Having said this, very many people are cured of their cancer by modern day treatment. The chances of getting a cure depend on the type of cancer that someone has, how advanced (how large it was and how far it had spread) at the time it was first discovered (this is sometimes known as the ‘stage’ of the cancer) and how well that cancer responds to treatment.

There are now masses of statistics which doctors can use as a guide to predicting the chances of a cure for any particular cancer at any particular stage. These show that for some of the more curable types of cancer the chances of the cancer coming back after treatment are very small indeed, particularly if it was discovered at an early stage. Whereas for other types or  cancers diagnosed when they were more advanced, the outcome is likely to be poorer.

These figures are only ‘statistics’ which means they cannot absolutely predict what will happen to an individual but they do give a good idea of the ‘chances’ of whether, or not, someone will be cured. So doctors rely on these figures for deciding what the likely outcome is for each person at the end of their treatment.

These days many many people are cured of their cancers. So if your doctors have given you the ‘all clear’, although there is no absolute way of proving they are right and guaranteeing you are cured, they obviously think your chances of success are excellent and you should look forward to the future with confidence.

I have recently finished treatment for a cancer. My doctors have given me the all clear but how can I be sure I am cured and the cancer won’t come back?

Despite the advances that have been made in the treatment of cancer there are still many tumours that cannot be cured. In these situations it often possible for different treatments to stop the growth and spread of the cancer, or even to shrink  it for a period of time.

Depending on the type of cancer and treatment which has been given this period of time when the tumour is no longer growing may last from a few weeks to a number of years.During this time the tumour is said to be  under control or ‘stable’. 

Other phrases which are sometimes used to describe this situation are ‘static disease’ and ‘ISQ’ (in status quo). If the cancer has shrunk  by at least 50% before the period of ‘stabilisation’ this may be referred to as a ‘partial remission’ or ‘partial regression’ or ‘partial response’ (all three terms mean the same thing).

Small changes in tumour size, either recorded by direct measurement or by looking at images on x-rays or scans are difficult to assess precisely. Therefore there is general agreement among cancer specialists that in order for a cancer to show signs of progression, or a relapse, there must be a greater than 25% change in the measurements that have been used to assess it. So provided that any change is less then this level, and assuming there has been no other evidence to suggest the disease is becoming active again), then the condition will still recorded as being ‘stable’.

My mother is having treatment for a cancer. The doctors have said she cannot be cured but have told her that because of treatment her condition is now stable. What does this mean?

In the early days of radiotherapy treatment, skin burns during treatment and sometimes permanent damage or scarring of the skin, was common.

This changed during the late 1950s and 1960s as two new types of machine were introduced to give the radiotherapy treatment. These are called Linear Accelerators and Cobalt Units. These machines produce irradiating rays of a much greater energy than the previous machines. This higher energy of the rays give the treatments greater accuracy and greater penetration of the tissues (allowing treatment of cancers deep inside the body and also reduce skin damage. This is because the high energy rays pass through the first centimetre or two of the first tissue they meet, before they actually begin to give out any radiation.
 
Skin problems are uncommon with modern radiotherapy treatment. Occasionally skin problems can occur because of the location of the cancer and the area of the body treated. Usually this will cause no more than some temporary pinkness or redness of the skin for a week or two after treatment. If any soreness does develop it will only last a short time and can usually be eased with creams or lotions, which you will be given at the hospital. Severe or permanent skin damage is  rare indeed.

The fact that skin damage was common forty or fifty years ago means that people can remember friends or relatives who had bad experiences with their radiotherapy treatments which  probably account for the stories you have heard. Nowadays the situation is very different and things have improved enormously.

I have cancer and have been told I will need radiotherapy. I am so frightened that the radiotherapy will burn me. I have heard such a lot of stories about this. What can I do?

Radiotherapy is almost always a local treatment, limited to a particular part of the body. Only the skin in that area will be irradiated and the skin elsewhere will not be affected.

The doses of radiotherapy used can vary but even with quite high doses modern radiotherapy machines usually cause a little skin irritation. Even so this does mean that the skin which has been irradiated will be more sensitive to sunlight than your normal skin.

The degree of sensitivity will vary from person to person. The increased sensitivity also reduces gradually with time but probably never disappears completely.

Having had radiotherapy does not mean you must avoid the sun completely but you should take care over exposing the treated skin. It is very important to cover the treated area for at least the first year after radiotherapy. Wear clothing made of cotton or natural fibres which have a closer weave and offer more protection against the sun. Even after this time the area treated will be more delicate, so extra care should be given. You should also use a high factor sunscreen (of at least factor 15). Remember, too much sunbathing does carry the risk of leading to skin cancer and should be avoided.

Very occasionally radiotherapy is given to the whole body. In this situation the doses are normally quite low but you should still take precautions in exposure to strong sunlight. Seek advice  from your doctors if you are having this type of treatment.

I am about to have a course of radiotherapy following an operation for cancer. If I go on holiday in a few months from now, will I be able to go out in the sun?

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