What is the role of chemotherapy in the treatment of rhabdomyosarcoma?

Updated: Feb 01, 2019
  • Author: Amelia F Drake, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

Answer

Risk-factor analysis based on a combination of staging and histology is the primary means for determining the appropriate course of chemotherapy.

Patients at low risk and those with the most favorable prognosis include individuals with embryonal rhabdomyosarcoma occurring at favorable sites. These include the orbit, nonparameningeal areas of the head and neck, genitourinary nonbladder or nonprostate regions, and biliary tract (stage I). Also included are patients with embryonal rhabdomyosarcoma at unfavorable sites with completely resected disease (group I) or embryonal rhabdomyosarcoma at unfavorable sites with microscopic residual disease after resection (group II). For patients with this prognosis, the most common regimen is a combination of vincristine and dactinomycin (VA protocol). [18] In certain subpopulations with preexisting renal abnormality that predispose them to nephrotoxicity, cyclophosphamide is often added (ie, VAC protocol). The overall survival rate for this group is more than 90%. [19]

Patients with intermediate risk and an intermediate prognosis include those with embryonal rhabdomyosarcoma at unfavorable sites and gross disease, those who are younger than 10 years and who have metastatic embryonal rhabdomyosarcoma, and those with nonmetastatic alveolar rhabdomyosarcoma at any site. Standard treatment for these patients is the VAC protocol with the addition of radiation therapy. The new IRS-V protocol calls for the addition of topotecan to the standard treatment regimen. Survival rates at 5 years after diagnosis are 55-70%.

Patients with metastatic disease (except the subgroup in the intermediate category) have a survival rate of approximately 30% despite both chemotherapy and irradiation and are therefore considered to be at high risk with a poor prognosis. Like the intermediate group, this group most commonly receives the VAC protocol. IRS-V recommendations call for the addition of irinotecan in this group.

Several new chemotherapeutic agents, including doxorubicin, cisplatin, etoposide, ifosfamide, topotecan and melphalan, have been tested in various combinations with and without the standard VAC protocol. However, none of these is superior to VAC alone. With high-dose chemotherapy with reconstitution of stem cells, high-risk patients with metastatic disease have a relapse-free survival rate of 19-44%. However, 1 comparison of this therapy to standard VAC chemotherapy with radiation therapy showed no significant survival advantage to stem cell reconstitution.


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