Sarcomas are malignant tumours derived from mesenchymal cells (bone, cartilage, blood vessels, muscle, fat, nerves and connective tissue, including that present in the organs), and can develop at any site in the body. There are many different types of sarcomas, but they are usually grouped into soft tissue sarcomas or bone sarcomas. Sarcomas are rare cancers: the 21st group of cancer in descending order of incidence. Due to its rarity, a GP can expect to see only one or two sarcomas in an entire career. There are approximately 4630 soft tissue sarcomas and 670 bone sarcomas diagnosed each year in the UK.

Soft tissue sarcomas account for about 1% of all malignant tumours. The cause of these tumours is not known, although they may be associated with previous radiotherapy, some toxins, and very rarely may be hereditary. They can affect any age group, although are more common in the middle-aged and elderly, and less common in younger age groups. There are many different histological subtypes of soft tissue sarcomas, although the commonest include undifferentiated pleomorphic sarcoma,  liposarcomaleiomyosarcomamyxofibrosarcomasynovial sarcoma, and malignant peripheral nerve sheath tumour. Nearly 60% of soft tissue sarcomas arise in the arms or legs, 20% in the trunk, 5% in the head and neck, and 15 - 20% in the abdomen or internal organs. The commonest sarcoma arising from the gut is gastrointestinal stromal tumour. The signs and symptoms of sarcomas vary according to where they develop, but often the first sign is of a lump in an arm or leg. Worrying features that might indicate a sarcoma include size greater than 5cm, a lump that is increasing in size, and pain.

Newly diagnosed soft tissue sarcomas are usually treated with surgery. Sometimes radiotherapy may also be given either before or after surgery. Chemotherapy can be used to treat localised tumours, although less commonly. For advanced tumours that have spread around the body, chemotherapy is usually the most important part of treatment, although radiotherapy can also sometimes be helpful.

Bone sarcomas are primary bone cancers and are very rare, accounting for 0.2% of all malignant tumours. They are commonest in children, teenagers and young adults, accounting for 4% of all malignancy in children up to 14 years, although much less commonly they can occur in older age groups. The cause of bone sarcomas is not known, although they may be associated with underlying bone diseases, previous radiotherapy, and very rarely may be hereditary. The commonest types of bone sarcomas are osteosarcomaEwing's sarcomachondrosarcoma and spindle cell sarcoma. They can arise in any bone in the body, although are most common in the limbs and pelvis. Initial symptoms usually include pain, tenderness and swelling of the affected bone, or an unexpected fracture.

Bone sarcomas are particularly aggressive tumours that are usually treated with a combination of surgery and long courses of chemotherapy. Modern surgery aims to remove the primary tumour, while at the same time preserving the limb function (or other body part) wherever possible. This is usually done by replacing the bone with a metal prosthesis. Radiotherapy is sometimes used after surgery, or instead of surgery if an operation is not possible.

Secondary bone cancers are much commoner than primary bone cancers. These are cancers that have spread from primary cancers arising in other parts of the body. The most common primary cancers to spread into bone are breast, prostate, kidney, lung and thyroid cancer. People with secondary bone cancer will often have multiple secondary tumours (metastases) in different bones.