2.6 Surgical resection
2.6.1 Expert Consensus
Pediatric parameningeal tumors typically present with locally advanced
disease secondary to the non-specific nature of the symptoms that they
cause. Due to the anatomical constraints and infiltrative nature of
parameningeal tumors, it is very difficult to obtain oncologically
negative margins without compromise of form and function (for example,
cranial nerve deficits, disfigurement of the facial bones). Surgical
resection thus holds a minimal role in the upfront management of PM-RMS
and should, for the most part, only be considered for non-parameningeal
head and neck sites where resection can be done with minimal morbidity
and little cosmetic/functional deficits. For PM-RMS specifically,
surgical approaches have typically been limited to biopsy and salvage
for recurrent disease. If resection is performed, a multidisciplinary
team at a specialized center should be involved, including
otolaryngology, neurosurgery, plastic surgery, and oral maxillofacial
surgery.
2.6.2 Evidence
The large majority of patients with parameningal tumors
(~95%) will have IRS group III disease secondary to the
anatomical difficulties and morbidity of performing a gross total
resection at diagnosis.6,35 Surgery for parameningeal
sites has been considered to be unfavorable, due to risk of
disfigurement, injury to neurovascular structures, and difficulty in
achieving complete resection.51,52 Common toxicities
of surgical resection for parameningeal tumors can include cranial nerve
palsy, CSF leaks, trismus, and poor cosmesis.1
With advances in endoscopic approaches and the quality of imaging,
certain tumors within the nasopharynx, sinonasal cavities, and skull
base without dural involvement may be amenable to endoscopic approaches
at specialized treatment centers.53 If surgical
resection is considered, smaller tumors (<5 cm, those without
dural involvement) appear to be more amenable to resection relative to
larger ones.51 Primary resection in smaller tumors may
have advantages such as avoidance of short and long term morbidities
associated with radiation to the pediatric skull base and sinonasal
cavities as described in small series.51,53 However,
there is often difficulty in obtaining negative margins, necessitating
postoperative radiation therapy.52,54 The advancement
of microsurgical techniques has also rendered surgery a treatment option
in select cases. When amenable to resection, these tumors are usually
approached through a transfacial or cranio-orbito-zygomatic approach,
which requires reconstruction after tumor resection is completed. Use of
free tissue transfer has enabled the ability to reconstruct areas once
thought to be unreachable by pedicled vascular
flaps.55
In the hands of experienced surgical teams, there appears to be a low
risk of severe postoperative morbidity, although this is very dependent
on experience. The morbidity of surgical resection combined with the
potential need for adjuvant radiation must be carefully evaluated for
each patient.53,56 In the minority of patients who
were able to undergo initial resection with microscopic residual disease
on COG protocols, the addition of surgery with resulting lower IRS group
was not associated with an improvement in outcomes,4and radiation continued to be delivered in the setting of microscopic
residual disease and/or positive margins (IRS group II). In addition,
when performed as a delayed primary excision or second look surgery,
although radiation doses can be reduced to 36-41.4 Gy, radiation is
still necessary, and there is no clear oncologic benefit from delayed
primary excision in this setting for PM-RMS.57 In
general, the tradeoff in morbidity between the reduction in radiation
dose with the addition of surgery in the setting of delayed primary
excision must be further explored with quality of life and late effect
assessments on future rhabdomyosarcoma protocols.58Overall though, without an oncologic benefit with the addition of
surgery to radiation, the acute and long-term toxicity of trimodality
therapy must be carefully considered and selectively applied.