Sarcoma PART – 2
(All the articles published in past are available at www.shyamhemoncclinic.com/blog/)
Question: Thank you Chiragbhai for explaining important points related to Sarcoma – tumors of connective tissue, low in numbers but important nevertheless and peculiar for several reasons. Mainly 1. Good cure rates in many sarcomas. 2. Many are seen in children and young adults. 3. Most subtypes have no known etiology. Trauma frequently draws patient attention to the site, but not a cause 4. Two main categories are: Soft tissue sarcoma AND Bone sarcomas. Also can be categorized as Extremity, Retroperitoneal, Other less common sites. 5. Diagnosis depends on radiology studies and biopsy. Unlike most other tumor types, radiology input in diagnosis is much higher. 6. Biopsy should be done by a surgeon conversant with treatment of sarcomas.
We discussed biopsy briefly last time. Can you tell us more about sarcoma pathology?
Ans: Sarcoma includes about 100 different histology types. Treatment and prognosis however depend more on size, grade, site. Some histology types are specifically important, however, as it has impact on treatment choice e.g. Ewing sarcoma, Osteosarcoma, Rhabdomyosarcoma, GIST (gastrointestinal stromal tumor), kaposi sarcoma,…. First three are especially notable for very high cure rates with multidisciplinary treatment and also young age in most cases. GIST is notable for a very specific targeted therapy. Kaposi sarcoma is mainly associated with HIV and is treated very differently.
More and more number of histologies are now becoming important however due to identification of molecular/cytogenetic targets, and availability of targeted therapies. Some subtypes are also treated by newer chemotherapy drugs or older but non chemotherapy drugs.
Most common among soft tissue sarcomas are GIST, followed by UPS (undifferentiated pleomorphic sarcoma. Previously known as MFH i.e. malignant fibrous histiocytoma), liposarcoma, leiomyosarcoma.
Size as mentioned above has big impact on survival. For example, high grade sarcomas with T1 stage i.e. Less than 5 cm, have cure rates of over 70% But this drops to about 10% for those over 20 cm size.
AJCC staging system takes into account both SIZE and GRADE. Same is true for Bone Sarcomas for staging.
¬Que: Thank you. Can you tell us about treatment of soft tissue sarcoma?
Ans: SOFT TISSUE SARCOMAs are primarily treated by surgery.
Radiotherapy is used post operatively or preoperatively in large tumors.
Similar to many cancer types, surgery is now less radical, and amputation is avoided more often than in past (limb sparing surgery). Radiotherapy is helpful in this context, given preoperatively.
Most tumors over 5 cm size, or positive margins are treated by postoperative radiotherapy.
Postoperative chemotherapy is controversial at best, and is generally not used.
For patients who are inoperable due to site/size or medical combodbidities, can be treated by radiotherapy for local control. While it does not provide same cure rates as surgery, it can still provide fairly good control rates with minimal morbidity.
For patients where both surgery and radiotherapy is not feasible or failed, or metastatic disease, chemotherapy and other medical options are useful for palliation. Most common site of metastasis is lung. All patients with metastatic disease do not need immediate treatment. Many patients have asymptomatic low volume spread, especially true with lung metastases. These patients can be kept on observation without active treatment. Some of the lung metastases patient, ones with few lesions and slow growth, can even be offered resection, if these are the only sites and all are amenable for resection.
Most commonly used chemotherapy agents have been doxorubicin, ifosfamide in past. Nowadays more frequently used drugs are Docetaxel, gemcitabine – significantly better tolerated compared to older agents. Not much better however in terms of efficacy. Most chemotherapy response rates are around 30-50% at best. Eribulin has shown good activity especially in liposarcoma, for which it has a specific approval as well.
Angiosarcoma responds to paclitaxel. A recent paper has shown good results with good old antihypertensive propranolol.
July 15th 2019. Dr. Chirag A. Shah; M.D. Oncology/Hematology (USA), 079 26754001. Diplomate American Board of Oncology and Hematology. Ahmedabad. firstname.lastname@example.org