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.