Early diagnosis of bone tumours

An article by Dr Rob Grimer FRCS

Primary malignant bone tumours are very rare, so rare in fact that most doctors will never see one in a lifetime. In the UK there are about 400 new primary malignant bone tumours a year, or 1 in 125,000 people so a GP with about 1500 patients would expect to see a new bone tumour once every 83 years!

There are four main types of bone tumour; osteosarcoma, Ewing’s sarcoma, chondrosarcoma and a mixed bag of tumours called spindle cell sarcomas (which include such types as fibrosarcoma, malignant fibrous histiocytoma and leiomyosarcoma).

Despite their rarity however, bone tumours are important because they often arise in children or adolescents and furthermore there is convincing evidence that the smaller the size at diagnosis, the better the prognosis.

The problem with diagnosing bone tumours is that they present in a variety of ways and to a variety of different people, most of whom will not be thinking of the possibility of a bone tumour, particularly in younger people. Bone tumours tend to start inside the bone when a cell turns malignant and then gradually the number of these malignant cells increases. Some bone tumours will weaken the bone and some will simply expand through the cortex (edge) of the bone and then extend into soft tissues.

The most common initial symptom experienced by patients is a dull ache. Initially it will be intermittent but will then become constant and will start to wake the patient at night. It is a non-mechanical type of pain, ie it is not made worse by activity. Of course, aches and pains are very common in the normal population but it is the persistence of the pain that should cause concern, particularly in a young person.

As the tumour gets bigger it will start to grow out of the bone and at that stage a lump may be palpable. This may in fact be the first presenting feature of some slow growing tumours such as chondrosarcomas, which can be totally painless.

The most common site for bone tumours to arise is around the knee, as shown below in Table 1. Hence any patient with persistent symptoms of non specific pain around the knee warrants investigation. The problem of course is that knee pain is very common at all ages and has many causes, anterior knee pain in children, torn cartilages in young adults and osteoarthritis in older patients. The main clinical finding however is that the bone itself is tender, unlike all of the other conditions where there are more specific findings.

 

Ewings

OS

CS

Distal Femur

10%

46%

11%

Prox Tibia

10 %

23 %

6 %

Pelvis

25 %

4 %

28 %

Prox Humerus

8%

9 %

10 %

Prox Femur

14 %

5 %

20 %

Fibula

10 %

5 %

1 %

Diaphyseal

10 %

2 %

1 %

Hand / foot

 

 

8 %

 

Table 1. Table to show the location of the different bone tumour types, expressed as a percentage of the total for that type.

In some patients there are more unusual methods of presentation. Tumours of the upper femur traditionally cause referred pain that is felt around the knee and this can be very deceptive. In someone with knee pain but no clinical signs examination of the thigh and hip is mandatory. Tumours of the pelvis, notably Ewing’s sarcoma or chondrosarcoma often have very few symptoms until a large mass is present, although referred pain to the leg, simulating sciatica can be present. Another dramatic way of presentation is with a pathological fracture. This arises when a bone, already weakened by a tumour, fractures, often with minimal force being applied to it. In most patients there is a past history of some discomfort in the bone preceding the fracture and either this, or the minimal force needed to produce the fracture should immediately raise the suspicion that there is a potential underlying tumour.

In anyone with these non specific symptoms the investigation of choice is an Xray. The features that should cause concern of a potential bone tumour are:

  • New bone formation
  • Periosteal elevation
  • Bone destruction
  • New bone formation

The presence of any of these should cause concern about a potential bone tumour and warrants further investigation.

It is notable that no mention has been made of any blood tests or other simple investigations which can help diagnose a bone tumour – there simply aren’t any reliable ones. Furthermore very few patients feel ‘ill’ with a bone tumour, they do not lose weight or go off their food.

Once the X-ray has raised the suspicion of an abnormality in a bone, the next step should be prompt referral to an orthopaedic surgeon, preferably one specialising in the management of bone tumours. They will arrange appropriate further investigations and biopsy to confirm or refute the diagnosis. Then treatment can commence.

The problem with diagnosing bone tumours is that they are so rare that most doctors do not even consider them as a potential diagnosis until they are fairly obvious. It is not at all uncommon for patients to have seen many health care workers, including doctors and physiotherapists before the diagnosis is made.

In 1990 we prospectively reviewed the history of patients presenting to our unit in Birmingham with newly diagnosed bone tumours, finding that for patients with osteosarcoma the delay in diagnosis averaged 16 weeks from first relevant symptoms, and for Ewing’s sarcoma the delay was 31 weeks. In both cases the patients had put up with their symptoms for about half the time (osteosarcoma 7 weeks and Ewings 16 weeks) before going to see a doctor. The remainder of the delay was due to ‘doctor delay’, ie the time taken between seeing the doctor and a diagnosis being made. In all cases the diagnosis of a possible bone tumour was made on the basis of an abnormal Xray, but, 25% of the patients had their diagnosis delayed because the Xray had been incorrectly reported as being normal or showing some other benign process. In these patients with a ‘reassuring’ Xray report, it was not surprising that on average their diagnosis was delayed more than 12 weeks longer than those in whom the Xray was correctly interpreted.

We had hoped that with the passage of time we would find that bone tumours would be diagnosed earlier – so that the both the size of the tumours and the length of the history would decrease.

Our unit has been keeping records for over 20 years of both size at diagnosis and duration of symptoms for all patients with new tumours. Unfortunately there has been little improvement with time. The median size of all bone sarcomas has averaged 10cm for over 20 years with no significant change with time and no difference between Ewing’s sarcomas and osteosarcomas. What is even more disappointing is that the duration of symptoms has not changed significantly either – in fact, for osteosarcoma patients the duration of symptoms has slightly increased to an average of 20 weeks with the passage of time, whilst for Ewing’s sarcoma patients there has been a slight improvement to 24 weeks.

This experience is not unique to the UK, almost every country has many patients who still present with large tumours and have experience of long delays before diagnosis is made. What is different in many countries however is that some health care systems empower patients to insist on Xrays or even mores sophisticated investigations and this may lead to earlier diagnosis although no study of this has ever been carried out.

What can be done to improve this, to increase awareness of bone tumours and to reduce the delays in diagnosis? Recent NICE Guidance in the UK has included very specific guidance for what doctors should do if they suspect a bone tumour ( http://www.nice.org.uk/guidance/csgsarcoma ) and also what the clinical features are that should raise suspicion ( http://www.nice.org.uk/page.aspx?o=cg027) . This does not seem to have made much of an impact for bone sarcoma diagnosis however and it really needs greater public awareness of the potential diagnosis as well. How this can be achieved is difficult to know – maybe a well known actor in a ‘soap’ could develop a bone tumour (complete with 12 weeks of aches and pains and several visits to the GP en route to the diagnosis) or maybe articles in ‘glossy magazines’ could highlight it.

At the end of the day, earlier diagnosis can only be beneficial to patients; a smaller tumour is easier to treat with a better prognosis for the patient.

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