Sarcomas are cancers originating from "mesenchymal" cells such as bone, cartilage, adipose tissue, connective tissue, muscle tissue, and vessel. They are named according to the tissue they originate from; for example, osteosarcoma means bone origin, chondrosarcoma cartilage, liposarcoma fat tissue, fibrosarcoma connective tissue, leiomyosarcoma or rhabdomyosarcoma muscle tissue, and hemangiosarcoma vessel. Sarcomas are not very common and they may originate from a wide variety of tissues. However, as patients live longer, the number of patients with sarcoma in the community (prevalence) increases. Sarcomas are tumors of all ages; 50% of bone sarcomas and 20% of soft tissue sarcomas are seen under 35 years of age.
How are they diagnosed?
Sarcomas are detected by imaging methods such as ultrasound, CT and MRI taken either for tumor-related complaints such as pain or for unrelated reasons just by chance. In the next step, a pathological diagnosis is made by imaging-guided needle biopsy. In the pathology, both the tumor type is revealed and the grade (low, medium or high grade) is determined. As the grade rises, the tumor becomes more aggressive, the growth rate increases and the likelihood of distant metastasis increases.
How are they treated?
Classical treatment methods for sarcomas are surgery, radiotherapy and chemotherapy. Treatment to be applied is determined by the type, grade and extent of the tumor. In general, surgical operation is preferred for local low-grade sarcomas. In other cases, one treatment is usually not sufficient; chemotherapy, radiotherapy and surgery should be applied in different combinations. However, some sarcoma types may be resistant to chemotherapy and some may be resistant to radiotherapy. In many patients, in whom these treatments have been applied, the patient may develop resistance or recurrence. In these cases, additional therapies should be applied.
Minimally invasive therapies in sarcomas
In low grade and non-metastatic sarcoma, the first treatment option is surgery. However, in patients who are not suitable or have developed recurrence after surgery, the ideal treatment is percutaneous ablation. The most commonly used method for percutaneous ablation of sarkomas is cryoablation, although radiofrequency and microwaves can sometimes be used. The type of the ablation to be used is determined according to tumor location, size and proximity to critical organs. However, because it is painless, can be done under local anesthesia, can also be used in large tumors and the ablation area can be clearly seen on ultrasound and CT during the procedure, cryoablation is preferred.
In sarcomas located in the limb, sometimes it may be necessary to reduce the tumor in size before operation. In such patients, if neoadjuvant chemotherapy is administered from the artery (intraarterial chemotherapy), the effect of treatment may be augmented and systemic side effects may be reduced. Intraarterial chemotherapy is a technically easy, safe and effective method in extremity sarcomas.
The most common site for metastases of sarcomas is the lung. Surgical operation is generally not suitable because the metastases are numerous and frequently recur. Radiotherapy is also not an option for the same reasons and because many sarcoma types are resistant to radiotherapy. In such cases, one of the best treatment methods is percutaneous ablation. Radiofrequency, microwave and cryoablation methods can all be used successfully, although cryoablation is more preferred due to its advantages. The ideal candidates are patients with oligometastases (not many) or oligorecurrence (not growing fast). The slow growth rate of metastases is very important; In such cases, tumors may be taken under control in some cases, even if the number of metastases in the lung is 10-15.
Sarcomas may also metastasize to many tissues and organs other than the lung. In such cases, percutaneous ablation is a good option if the tumors are suitable for ablation and the growth-proliferation rate of the metastases is slow. Various ablation methods can be preferred depending on the location, size and number of the metastases. In liver, radiofrequency and microwave, and in soft tissues cryoablation are preferred. All methods can be used for small metastases, but cryoablation may be more suitable for large metastases.
Interventional oncology in cancer management
Prof Saim Yilmaz, MD