Clinical history and physical examination is always the first investigation.
- Blood work: CBC, electrolytes, creatinine, urea, liver enzymes, calcium, phosphate, magnesium, LDH, uric acid, PTT, INR, urinalysis and a pregnancy test (if applicable)
- No specific tumor markers for rhabdomyosarcoma
- Imaging: X-ray of the primary site
- MRI &/ CT of primary lesion
- Chest CT scan to exclude pulmonary metastatic disease
- Bilateral bone marrow aspiration and biopsy to exclude bone marrow metastatic disease
- FDG PET–CT scan to determine baseline extent of disease
- Bone scan (sometimes not done if PET-CT has already been performed)
- CSF examination if parameningeal primary tumor
Summary of staging investigations for RMS:
Evaluation of primary tumor site
CT – define tumor extent
MRI – define soft tissue and bone marrow extent
Biopsy - must be carefully planned
EUA (examination under anesthetic) may give useful information about the extent of disease e.g. for GU and nasopharyngeal tumors.
Evaluation of metastatic disease
CT of the chest is always performed to look for pulmonary nodules
Bone scan for skeletal metastases
Bone marrow biopsy
For patients with parameningeal lesions with base of skull invasion, MR imaging of the craniospinal axis is important to exclude leptomeningeal spread as well as CSF cytology.
PET-CT scanning shows significant uptake in both primary and metastases. This is a useful investigation for staging if available.
The diagnosis is made by biopsy.
Lymph node biopsy is usually performed if there is clinical or radiological evidence of involvement.
All biopsies should be planned and performed very carefully. A poor biopsy in extremity lesions is likely to lead to problems:
- Delay in diagnosis (insufficient material).
- Transverse scar in an extremity – so adequate excision of the tumor bed is difficult and radiation therapy involves large fields which encompass most of the limb.
Consideration of fertility preservation
This should be discussed prior to treatment initiation
- Cyclophosphamide is included in standard RMS chemotherapy regimens, with the exception of a subset of low risk patients, and carries a high risk of future infertility.
- An open Children’s Oncology Group (COG) study (ARST 0331) will address effect of lower cumulative doses of cyclophosphamide on outcome and toxicity.
- The majority of patients require radiation therapy and this may additionally affect fertility depending on target volume.
- Sperm donation may be pursued for adolescent boys and egg harvesting may be possible for post-pubertal girls, although this needs to be done expeditiously prior to initiation of chemotherapy.
- Reproductive technology continues to improve and new options for fertility preservation even in pre-pubescent females, including ovary harvesting, are being explored.