Sarcoma – 4 – Bone sarcomas

Sarcoma PART – 4
(All the articles published in past are available at www.shyamhemoncclinic.com/blog/)

Question: Thank you Chiragbhai for explaining important points related to specific Sarcoma types –

1. GIST – a slow growing sarcoma treated with surgery, and imatinib (a drug first approved for a type of leukemia). Imatinib works on KIT mutation found in both GIST and leukemia (CML). Improves median survival from 15 months to 60 months, where no chemotherapy had worked. 2. Kaposi sarcoma – a tumor secondary to HHV 8 infection. Seen in both HIV and non HIV patients. very slow growing. If localized disease, generally observed without any treatment. If systemic, chemotherapy.
   What other specific subtypes are we going to discuss today?
   Ans: Yes it is interesting to discuss specific subtypes. However, we have to remember that our readers may not enjoy too many details about such rare cancers. Broad concepts and treatment plan for soft tissue sarcomas have been explained in second episode of this series. Of course, as our readers know too, decision making in an individual case requires careful evaluation of a lot of aspects, and that of continuous advances in the field of oncology too.
   We should however discuss BONE SARCOMAS now which we touched upon briefly in first episode of this series.
   These tumors are again rare but very important due to same reasons – most patients are children or young adults, early diagnosis can cure most, multidisciplinary planning is essential to ensure good functional outcome apart from cure. One of the peculiar aspects of bone sarcoma diagnosis is role of radiologist: Site of tumor (near joint or mid shaft for example), specific pattern of appearance are frequently diagnostic, and even pathologists take into account this input, in a number of cases.
   You will be pleased to know that now there are surgeons, even in India, including in Gujarat, who treat only SARCOMAs. This is a very important part of high quality treatment, considering how rare these tumors are. It is not easy to develop very good proficiency in rare tumors if you are operating all types of cancers. That too in a field like oncology where so many advances are coming frequently, in imaging, pathology, surgery especially reconstruction techniques or limb preservation techniques, chemotherapy, radiotherapy, physiotherapy and so on.
   ¬Que: Wonderful! It is good to have such experts around considering so many aspects to take care. If we can save a limb instead of full amputation, that is a huge step for quality of life. That too when most such patients are just starting out their life.
   Ans: Yes. Most common bone sarcomas are:
2. Osteosarcoma: primarily treated by surgery and chemotherapy. Chemotherapy may be given before or after surgery. Most such tumors are close to joint e.g. knee. Chemotherapy can reduce tumor size and allow a joint preserving surgery which has much better functional outcome. Cisplatin and doxorubicin is probably the most commonly used combination. Some experts prefer high dose methotrexate based combination, this however can be associated with extreme side effects, as the doses of methotrexate in this regimen are very high. Hence it is not used in all patients even in countries like USA. Overall survival has not been shown to be convincingly better with or without high dose methotrexate.
   Long term survival of osteosarcoma is significantly poor without chemotherapy, with spread to distant sites, most commonly lung. Surgery alone cures only about 20%, with chemotherapy this number is about 70-80%.
   Hence it is very important to ensure patient receives recommended cycles of chemotherapy. This is being reemphasized as role of chemotherapy in bone sarcomas is so much more than in soft tissue sarcoma. Whereas most patients and doctors may feel satisfied after a good surgery and may not complete chemotherapy, especially when there are side effects.
3. Ewing sarcoma: these tumors generally require all three modalities (chemotherapy before or after surgery) – surgery, chemotherapy, radiotherapy. Again with very good cure rates however. VAC (vincristine, doxorubicin, cyclophosphamide) cycle is alternated with IE (ifosfamide, etoposide). Some patients have soft tissue origin ewing sarcoma, more common in adults, rare in children.
4. Chondrosarcoma: These are tumors seen in adults. They are treated primarily by surgery.

September 17th 2019. Dr. Chirag A. Shah; M.D. Oncology/Hematology (USA), 079 26754001. Diplomate American Board of Oncology and Hematology. Ahmedabad. drchiragashah@gmail.com