What are sarcomas?
These are a diverse group of malignant tumours that originate from either Soft tissues or Bones.
Soft tissue Sarcoma- which includes tumors arising from muscles, tendons, blood vessels, nerves. Since these tissues are in found in all parts of the body hence the tumors can originate from any body part. Malignancy or aberrant growth in any of these tissues is called Sarcoma and is classified according to their respective tissue of origin.
Bony Sarcomas - tumors which arise from Bone. These are mainly classified according to the type of bone which they involve (flat bones- like skull/pelvis versus appendicular skeleton- humerus, femur) and also according to the site of disease (epiphyses/ metaphyses and Daiphyses) eg- Osteosarcoma, Ewing’s sarcoma.
Symptoms of Sarcoma
Soft tissue sarcomas can present as a lump in any part of the body which might be progressively increasing in size and causes pressure symptoms, such as pain due to pressure on nerves; or cough in case of pressure on the lung. When they are deep-seated they might present in an advanced stage.
Bony Sarcomas are diseases of relatively younger age group (teens or young adults and usually present with bony swelling or pain (from the site of bony origin). They may also sometimes present with fever (Ewing Sarcoma).
Incidence
STSs constitute a more heterogeneous group of tumors, with more than 50 different tumor entities. These tumors account for <1% of all adult tumors and 15% of pediatric tumors. Bony sarcomas constitute <0.3 % of all malignancies diagnosed in India. Osteosarcoma (OGS), chondrosarcoma, and Ewing sarcoma/primitive neuroectodermal tumor (PNET) are the common bony sarcomas seen worldwide.
Diagnosis of Sarcoma
Unfortunately, soft tissue sarcomas can be asymptomatic for a long time. Symptoms are usually pressure symptoms caused by the lump at the site of origin.
Radiology - X-rays for bone sarcomas /MRI and CT scans help to determine the extent and nature of these tumors.
Histology- Trucut / or a J needle biopsy from the most superficial planes must be obtained for diagnosis.
Staging forms an important part of investigations – This is done by screening common sites of metastasis like lung and liver.
Treatment of Sarcoma
Treatment for localised soft tissue sarcoma is confined to the primary site and is mainly surgical. Wide local excision is carried out which should include normal margins of the surrounding tissue.
Surgery for Bony Sarcomas focuses on Limb Preservation. This endeavour is now possible largely due to advanced prosthetic devices.
In Bony sarcomas especially Osteosarcoma and PNET /Ewing’s sarcoma-chemotherapy prior to surgery plays an important role in reducing the size of tumor and enhancing survival.
The result of treatment of localized disease is usually gratifying in most cases, however, patients are to be regularly monitored for any local recurrence
Precision Medicine in Sarcoma
Next-generation sequencing in sarcomas and targeted therapy- this is being used predominantly as a shotgun screening tool to seek out novel recurrent and potentially actionable mutations. Instances, where it has been proven to show benefits in Soft-tissue Sarcoma, are – Gastro-Intestinal Stromal tumor (GIST), which is now treated with an oral pill. Also, an upcoming group of mutations are NTRK fusion gene mutations for which therapy is now available in the clinical domain.
Conclusion
Management of sarcoma requires a team of doctors from various disciplines including Medical, Surgical and Radiation Oncology along with Pathologists and Radiologists. It all starts when the patient presents with soft tissue or bony swelling. Such cases should be discussed in Tumor Boards for laying out a comprehensive management plan for the best disease outcome.