What are the recommendations for systemic therapy for retroperitoneal soft tissue sarcoma?

Adjuvant chemotherapy (additional treatment given after surgery to lower the risk of the cancer returning) is not recommended as a routine standard of care in patients with retroperitoneal STS that have undergone surgical removal or tumour except in rare subtypes of cancer more common in children that are more sensitive to chemotherapy, e.g. Ewing sarcoma.

Leiomyosarcomas are moderately sensitive to one or several of these agents given singly or in combination:

1. Gemcitabine in combination with Docetaxel. Gemcitabine is a drug that inhibits cancer cell growth and promotes cancer cell death. Docetaxel is an anti-cancer drug that inhibits cancer cell division.

2. Single agent Trabectedin. Trabectedin is also sold as Yondelis, and reduces the cancer-like activities of the cancer cells.

3. Dacarbazine or Temozolomide, drugs that kill cancer cells by destroying their DNA.

4. Gemcitabine in combination with Dacarbazine.

Leiomyosarcomes are more sensitive to the above agents than anthracycline-based chemotherapy, which acts to prevent cancer cell division by disrupting the structure of the DNA.

Undifferentiated pleomorphic sarcoma and malignant peripheral nerve sheath tumours are treated with anthracycline-based chemotherapy consisting of a combination of drugs.

Some cancer cells produces many proteins known as vascular endothelial growth factors (VEGFs) that stimulate the growth of blood vessels that cancers need to support their growth. Anti-VEGF therapy inhibits these proteins, thus preventing the growth of cancer cells.

Single tumours that are fibrous in nature benefit from anti-VEGF therapy given either alone or in combination with chemotherapy.

Pazopanib remains an option for patients with any non-liposarcoma soft tissue sarcoma who have recurrent cancer or cancer that has spread to other sites in the body and have failed to respond to other chemotherapies.