Discussion
Rhabdomyosarcoma (RMS) is a malignancy of mesenchyme cells that have
varying degrees of differentiation towards skeletal muscle
cells1. The most common affected sites are head and
neck (28%), extremities (24%), with genitourinary tract only
comprising 18%2. Rhabdomyosarcoma is generally a
disease of children, and is exceedingly rare in
adults3.
Prostate RMS accounts for <1% of all prostate malignancies in
adult life4. It is described only in case reports.
Clinical presentation includes dysuria, urinary and rectal obstruction.
PSA levels are usually normal. Main sites of metastasis include the
lungs, liver and skeleton. Having a cancer predisposition syndrome, such
as Neurofibromatosis, Noonan, Li Fraumeni, is the strongest risk factor
for developing RMS5.
RMS is histologically divided into embryonal, alveolar, spindle
cell/sclerosing and pleomorphic subtypes. Each harbor characteristic
genetic aberrations6 with implications for
prognostication. Due to high discordance among pathologists, genetic
testing is used for confirmation.
For early stage RMS, surgical management aims for complete tumor
resection. For unrestable cases, the mainstay of treatment remains to be
chemotherapy. Vincristine sulfate, dactinomycin (actinomycin-D), and
cyclophosphamide (VAC) regimen remains the backbone of Pediatric RMS
chemotherapy8. Due to the rarity of the disease in
adults, there is a lack of standardized treatment in this age group, but
retrospective studies have shown that concordance with pediatric
protocols have better survival9. Hence our patient was
managed with VAC. Since VAC has been associated with high risk of
gonadal dysfunction, sperm cryopreservation was performed prior to
initiation.
Compared to children, adult RMS has significantly worse outcome.
Five-year overall survival in children was 61% compared to 27% in
adults (7). The reason for poor survival has been found to be due to
higher IRS stage, unusual histology and metastatic disease at the time
of diagnosis. Additional studies have shown other factors that
contribute to poor survival, including lack of compliance to the
regimen, delays in diagnosis and the lack of RCTs for the adult
groups11.
The advent of gene testing has implications for prognostication,
enabling identification of the specific genetic aberrations driving the
tumors. This area of research may help find potential therapeutic
targets in the future12.