All children with rhabdomyosarcoma require multimodality therapy with systemic chemotherapy, in conjunction with either surgery, radiation therapy (RT), or both modalities to maximize local tumor control.[1,2,3] Surgical resection may be performed before chemotherapy if it will not result in disfigurement, substantial functional compromise, or organ dysfunction. In most cases, this is not possible, and therefore, only an initial biopsy is performed. The majority of patients have Group III (gross residual) disease. After initial chemotherapy, Group III patients receive definitive RT for control of the primary tumor. Some patients with initially unresected tumors may undergo second-look surgery (delayed primary excision) to remove residual tumor. This is most appropriate if the delayed excision is deemed feasible with acceptable functional/cosmetic outcome and if a modest reduction in radiation dose is expected to significantly reduce the risk of long-term adverse effects. RT is given to clinically suspicious lymph nodes (detected by palpation or imaging) unless the suspicious lymph nodes are biopsied and shown to be free of rhabdomyosarcoma.
The discussion of treatment options for children with rhabdomyosarcoma is therefore divided into separate sections describing the following local control options:
Merkel cell carcinoma (MCC) was originally described by Toker in 1972 as trabecular carcinoma of the skin. Other names include Toker tumor, primary small cell carcinoma of the skin, primary cutaneous neuroendocrine tumor, and malignant trichodiscoma.
MCC is an aggressive neuroendocrine carcinoma arising in the dermoepidermal junction. (See Figure 1) Although the exact origin and function of the Merkel cell remains under investigation, it is thought to have features of both epithelial and neuroendocrine...
The treatment of rhabdomyosarcoma by the Children's Oncology Group (COG) and in Europe (as exemplified by trials from the Intergroup Rhabdomyosarcoma Study Group [IRSG], the Soft Tissue Sarcoma Committee of the COG [COG-STS], and the International Society of Pediatric Oncology Malignant Mesenchymal Tumor [MMT] Group) differs in management and overall treatment philosophy. In the MMT trials, the main objective is to reduce the use of local therapies using initial front-line chemotherapy followed by second-line therapy in the presence of poor response. Subsequent surgical resection is preferred over RT, which is used only after incomplete resection, documented regional lymph node involvement, or a poor clinical response to initial chemotherapy. This approach is designed to avoid major surgical procedures and long-term damaging effects from RT. Conversely, the primary COG-STS objective has been to employ local therapy soon after the initial operation or biopsy (except in patients with metastatic disease), using RT for patients with residual disease. Event-free survival (EFS) is the target endpoint, attempting to avoid relapse and subsequent salvage therapy. The MMT Group approach led to an overall survival (OS) rate of 71% in the European MMT89 study, compared with an OS rate of 84% in the IRS-IV study. Similarly, EFS rates at 5 years were 57% in the MMT89 study versus 78% in the IRS-IV study. Differences in outcome were most striking for patients with extremity and head and neck nonparameningeal tumors. Failure-free survival was lower for patients with bladder/prostate primary tumors who did not receive RT as part of their initial treatment, but there was no difference in OS between the two strategies for these patients. The overall impression is that survival for most patient subsets is superior with the use of early local therapy, including RT. However, in the MMT trials, some patients are spared aggressive local therapy, which may reduce the potential for morbidities associated with such therapy.[1,2,3]