Epidemiology

Rhabdomyosarcoma, a tumor of striated muscle, has the following epidemiologic characteristics:

• It is the most common pediatric soft-tissue sarcoma, with an incidence of 4.6 per million in children 0-14 years old, and it constitutes 5.8% of all malignant solid tumors in children.

• Among extracranial solid tumors, rhabdomyosarcoma is the third most common solid tumor, following neuroblastoma and Wilms' tumor.

• It accounts for 3.4% of all malignant neoplasms in children of the United States. Approximately 350 new cases are diagnosed in the United States each year. The male:female ratio is 1.1-1.5:1.

• There are two age peaks: 2-6 years and 15-19 years. Incidence in African-American females is half that of Caucasian females. Incidence is lower in Asian populations residing in Asia or the West.

Fibrosarcoma, the most common group of NRSTS tumors, is most common in infants, whereas others predominate in mid- to late adolescence.

Table 20-1. Clinical and Biological Features of the Nonrhabdomyosarcoma Soft Tissue Sarcomas (NRSTS)

Tumor"

Cell origin/ cytogenetics

Common sites

Common ages

Good prognostic factors'

Outcome

Therapy

Synovial sarcoma

Mesenchymal cells/t(X;18)

6 Malignant fibrous Fibroblast/19p+ 2

histiocytoma

Angiomatoid form Malignant peripheral nerve sheath tumor Fibrosarcoma

Congenital Adult form

Schwann cell or fibroblast/17q, 22q loss or rearrangement Fibroblast t(12;15)

Extremities (lower>upper)

Lower extremity, trunk, head, and neck

Extremity

Extremity, retroperitoneum, trunk

Adolescence/ young adulthood

40-60 years

In children, 10-20 years

Young children

Younger in patients with neurofibromatosis (NF)

Extremity, trunk Most <2 years

Extremity (thigh, Adolescence knee)

Age <14 years Size <5 cm, calcification Extremity site

<5 years

5 year survival, 27-53%

Excellent with surgery alone 53% survival without NF, 16% with NF

Excellent with surgery alone

5-year survival 84%

5-year survival 34-60%

WLEC with/without RTd Chemo: ifosfamide/

Adriamycin WLE

Chemo: no established role; responsive to VACe +/- doxorubicin WLE

WLE with/without RT Chemo: neoadjuvant role, ifosfamide and etoposide active WLE, avoid amputation RT/chemo if WLE not possible Neo-adjuvant VAf useful WLE with/without RT Chemo: no established role

Leiomyosarcoma

Epithelioid forms Alveolar soft tissue sarcoma

Hemangiopericytoma6

5 Infantile form C> go

Liposarcoma

Smooth muscle t(12;14) Common in HIV+ children

Paraganglionic mesoderm (?), neuroepithelial (?), muscle (?) t(X;17) Pericytes t(12;19), t(13;22)

Primitive mesenchyme t(12;16)

Retroperitoneum GI tract, vascular tissue

Stomach

Lower extremity, head and neck

Extremity, retroperitoneum, head and neck

Extremity, trunk

Extremity, retroperitoneum

40-70 years, when in children, any age

15-35 years

20-70 years, when in children, 10-20 years

Rare, but typically

<1 year 0-2 years and second decade; sixth decade most common

Young age, orbital site, <5 cm

Child, myxoid type

33% disease-free survival at 1-5 years

Excellent with surgery alone 5-year survival 27-59% (indolent; death from disease after 10-20 years Stage I & II, 30-70% 5-year survival with adjuvant therapy Stages III & IV, poor Excellent with surgery alone Very good with WLE, rarely metastasizes

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